IM 684-2 1

Installation and Maintenance Manual IM-684-2

Group: Applied Systems

Part Number: IM684

Date: June 2001

Forced Draft Gas Fired Furnaceon McQuay Applied Rooftop SystemsFC ****A* with RM7895A Flame Safeguard

© 2001 McQuay International

2 IM 684-2

GeneralWarranty Exclusion .............................................................. 3 Ventilation and Flue Pipe Requirements ............................ 3 Factory Mounting............................................................... 3 Factory Checkout ............................................................... 3

Installation General ............................................................................... 3 Flue Box ............................................................................. 3 Wind Deflector ................................................................... 4 Electrical ............................................................................ 4 Gas Pressure Requirements................................................ 4 Gas Piping .......................................................................... 4 Valve and Regulator Venting.............................................. 5 Normally Open Vent Valve ................................................ 5 Gas Piping Routing into Unit ............................................. 6 On-the-Roof Piping (Models 020-140) .......................... 6 Through-the-Curb Piping (Models 020-140) ................. 6 Typical Piping Connections .............................................. 6 Gas Piping (Models 150-200) ........................................... 7 Gas Piping Within the Vestibule ....................................... 7 Field Gas Piping Required ................................................ 7 Condensate Drain .............................................................. 7 Vestibule (Models 150-200) .............................................. 7

Start-up & Operating Procedures Start-up Responsibility....................................................... 8 Start-up Procedure.............................................................. 8 Before Start-up ................................................................... 8 Start-up Preliminary ........................................................... 8 Low Fire Start .................................................................... 9 Pilot Start-up ...................................................................... 9 Main Flame Start-up .......................................................... 9 Typical Sequence of Operation .......................................... 9 On-Off Gas Burner............................................................ 9 Modulating Gas Burner..................................................... 9

Service General .............................................................................. 11 Pilot Air & Gas Adjustments ............................................ 11 Pressure Regulator ............................................................ 11 Pilot Orifice....................................................................... 11 Ignition Electrode Adjustment ..........................................11 Flame Rod Adjustment ..................................................... 11 Pilot Location Adjustment ................................................11 Air Pickup Tube Adjustment.............................................12 Gun Assemblies ................................................................12 Modulating Linkage Adjustment ......................................13 Combustion Testing ..........................................................13 Verify Input Rate ...............................................................13 Check CO2, CO and Stack Temperature ...........................13 Cleaning Heat Exchanger (Models 032-200)....................14 Cleaning Heat Exchanger (Models 020-025)....................14 Leakage Symptoms ...........................................................14 Checking for Leaks ...........................................................14 Causes of Failures .............................................................15 Replacing a Heat Exchanger .............................................15 Furnace Condensation.......................................................15 Rear Cleanout Port ............................................................15 Furnace Condensate Drain Kit .........................................16

Considerations ................................................................16Install .875 Copper Drain Line.......................................16Install the Cover Over Drain Pipe ..................................16

Combination Fan and Limit Control.................................17

MaintenanceMonthly, Twice Yearly, Yearly ........................................17

Flame Safeguard Characteristics & Operation..............................................17

Troubleshooting Chart ................................................. 19

Typical Parts List - 60 Hz ..............................................21

Capacities & Adjustments Table ..........................22

Performance & Service History ............................23

When writing to McQuay for service or replacement parts, refer to the model number of the unit as stamped on the serial plate,attached to the unit. If there is an in-warranty failure, state the date of installation of the unit and the date of failure along with anexplanation of the malfunctions and the description of the replacement parts required. Parts are warranted for ninety (90) daysunless covered by original unit warranty.

SERVICED BY:

TELEPHONE NO: INSTALLATION DATE:

Installer:Leave this manual with owner. It is to be posted and maintained in legible condition.

Table of Contents

IM 684-2 3

GeneralThis forced draft gas burner is specifically designed for usewith the furnace on McQuay applied rooftop heating and airconditioning units which are for outdoor installation only.Each model size has unique burner head components to tai-lor the shape of the flame to each particular stainless steelcombustion chamber, to match the capacity requirement, andto offer a desirable turndown potential when arranged formodulation. This is a forced draft burner with a high pres-sure combustion air fan and will operate against pressure.This eliminates the need for draft inducers, chimneys, drafthoods, barometric dampers, and Breidert caps.

Warranty ExclusionWarranty is void if furnace is operated in the presence ofchlorinated vapors, if the airflow through the furnace is notin accordance with rating plate, or if the wiring or controlshave been modified or tampered with.

Ventilation & Flue Pipe RequirementsThe McQuay applied rooftop unit is equipped with an out-door air louver to supply adequate combustion air. The unitalso has a flue outlet assembly and requires no additionalchimney, flue pipe, Breidert cap, draft inducer, etc.

Factory MountingThis burner and gas train has been installed and wired at thefactory. See "Gas Piping." Also note that models 150through 200 have the burner removed for shipment; see"Installation: Models 150-200."

Factory CheckoutThis complete heating plant was fired and tested at the fac-tory. It was adjusted to the required capacity and efficiency.Modulating air and gas linkages, pressure regulators, andstops were adjusted for proper operation at all firing levels.The unit was fired through several complete start-up throughshutoff sequences to check operation. A check was made ofthe air switch, gas pressure switch, high limit operation, andcombustion characteristics including C02 and CO (at severalfiring rates on modulating burners).

WARNING

Units equipped with gas heating must not be operated in an atmosphere contaminated with chemicals which will corrode the unit such as halogenated hydrocar-bons, chlorine, cleaning solvents, refrigerants, swim-ming pool exhaust, etc. Exposure to these compounds may cause severe damage to the gas furnace and result in improper or dangerous operation. Operation of the gas furnace in such a contaminated atmosphere consti-tutes product abuse and will void all warranty coverage by the manufacturer. Questions regarding specific con-taminants should be referred to your local gas utility.

If the burner was specified for operation at higher altitudes,combustion air adjustments were compensated to result inproper settings at the higher altitude. This checkout nor-mally eliminates on-the-job start-up problems; however, theequipment is subject to variable job conditions and shippingshocks can change adjustments, cause damage, and loosenconnections and fasteners. Therefore, it is necessary to gothrough the complete start-up procedure even though theunit may appear to be operating properly.

InstallationGeneralThe installation of this equipment shall be in accordancewith the regulations of authorities having jurisdiction and allapplicable codes. It is the responsibility of the installer todetermine and follow the applicable codes. Sheet metalparts, self-tapping screws, clips, and such items inherentlyhave sharp edges, and it is necessary that the installer exer-cise caution. This equipment is to be installed by an experi-enced professional installation company that employs fullytrained technicians.

Flue Box (see Figure 1.)The flue box is not installed at the factory because it wouldincrease the width of the unit beyond the allowable shippingwidth. All holes are pre punched, the fasteners are furnishedand everything is shipped inside the burner vestibule of theunit. On Models 150 through 200 it is shipped in the samecrate as the vestibule. Remove and discard the shippingcover installed over the furnace tube outlets before installingthe flue box.

1. Remove the screws (2) in the casing of the unit that lineup with the bottom lip holes of the flue box tube sheet(3). These screws will later be replaced, at which timethey will also attach the bottom of the flue box to theunit.

2. Install the flue box tube sheet (3), attaching top to roofdam strip with screws ➀. Do not attach bottom at thistime.

3. Apply a 1/8 to 3/16 inch bead of high temperature sili-cone around each tube to seal it to the flue box tube sheet(3) and prevent condensate from running back toward theunit along the outside of the tube. See Figure 1. Alsoapply a bead of high temperature silicone to seal bothsides to the bottom of the flue box wrapper (4), beingcareful not to obstruct the square drain holes in each frontcorner.

4. Install flue box wrapper sheet (4) by sliding it up frombelow so as not to disturb the silicone seal described in 3above. Attach with side screws (5). At this time reinstallbottom screws (2).

4 IM 684-2

Figure 2. Wind Deflector, Models (032 thru 140)

ElectricalThe McQuay burner receives its electrical power from themain unit control panel. No additional power wiring must berouted to the burner. The sequencing of the burner is alsocontrolled through this panel and therefore is factory wired.No additional wiring will be required. Note that models 150through 200 furnaces require reassembly of some electricalconnections as the burner is removed for shipment.

Gas Pressure RequirementsThe pressure furnished to the appliance gas pressure regula-tor immediately before the main gas valve must not exceed13.9 in. W.C. or be below the minimum specified in Table 5,Column 14. When the supply pressure is above 13.9 in. W.C.a high pressure regulator must precede the appliance gaspressure regulator. The inlet gas pressure cannot exceed themaximum pressure rating of the high pressure regulator andthe outlet pressure must be such that it will furnish gas to theappliance pressure regulator within the pressure range men-tioned above.

Gas Piping The connection size at the burner is shown in Table 5 underColumn 17 and 18. Gas piping must be sized to provide theminimum required pressure at the burner when the burner isoperating at maximum input. Consult your local utility onany questions on gas pressure available, allowing pipingpressure drops, and local piping requirements.

Install all piping in accordance with the National Fuel GasCode (ANSI Z223.1), (NFPA 54-1999) and any applicablelocal codes.

It is very important that the proper size piping be run fromthe meter to the gas burner without reductions. Undersizedpiping will result in inadequate pressure at the burner. Thepressure will be at its lowest when it is needed the most, attimes of maximum demand. Therefore, it can cause intermit-tent hard-to-find problems because the problem may haveleft before the service technician has arrived. Avoid the useof bushings wherever possible.

WARNING

Improper installation, adjustment, alteration, service or maintenance can cause property damage, injury or death. Read the installation, operating and maintenance instructions thoroughly before installing or servicing this equipment.

FOR YOUR SAFETY

If you smell gas:1. Open Windows2. Don’t touch electrical switches.3. Extinguish any open flame.4. Immediately call your gas supplier.

FOR YOUR SAFETY

The use and storage of gasoline or other flammable vapors and liquids in open containers in the vicinity of this appliance is hazardous.

4 3 5

1

2Drain Opening(both corners)

Seal SideSeams

Seal AroundEach Tube

Figure 1. Flue Box

Tube Ends

Flue BoxWrap

Flue BoxTube Sheet

Wind Deflector

Hinge InnerScrew

BurnerAccessDoor

4

3

Wind DeflectorThe wind deflector is not installed at the factory because itwould increase the width of the unit beyond the allowableshipping width. The deflector is shipped in the burner vesti-bule of the unit. Install the wind deflector over the combus-tion air intake opening of the burner compartment beforeoperating the burner. Use inner hinge screws on top hingeddoor (see Figure 2). Side hinged doors have holes for mount-ing (see Figure 5). Models 020 and 025 have a different stylewind deflector. It mounts on the door and has a top openingflush with the roof of the unit (see Figure 14).

IM 684-2 5

Remove all burrs and obstructions from pipe. Do not bendpipe; use elbows or other pipe fittings to properly locatepipe. A drip leg must be installed in the vertical line beforeeach burner such that it will not freeze. Install unions so gastrain components can be removed for service. All pipethreads must have a pipe dope which is resistant to theaction of LP gas. After installation, pressurize the piping asrequired and test all joints for tightness with a rich soapsolution. Any bubbling is considered a leak and must beeliminated. Do not use a match or flame to locate leaks.

Valve & Regulator VentingValve diaphragm vents, pressure regulator vents, and pres-sure switch vents are located in the outdoor burner vestibuleand therefore vent tubing is not run to the outside of this ves-tibule. If local regulations require that this be done, it is apart of the field gas piping hookup. Remove any plastic pro-tector plugs from regulator and valve vents.

Normally Open Vent ValveVent valves such as required by IRI for over 1000 MBHinput units must always be routed to the outdoors. This isfield piping.

Table 1. Capacity of pipe natural gas (CFH)

WITH PRESSURE DROP OF 0.3" W.C. & SPECIFIC GRAVITY OF 0.60

PIPE LENGTH (FT.)

PIPE SIZE-INCHES (IPS)½ ¾ 1 1¼ 1½ 2 2½ 3 4

10 132 278 520 1050 1600 2050 4800 8500 1750020 92 190 350 730 1100 2100 3300 5900 1200030 73 152 285 590 890 1650 2700 4700 9700

40 63 130 245 500 760 1450 2300 4100 830050 56 115 215 440 670 1270 2000 3600 740060 50 105 195 400 610 1150 1850 3250 6800

70 46 96 180 370 560 1050 1700 3000 620080 53 90 170 350 530 990 1600 2800 580090 40 84 160 320 490 930 1500 2600 5400

100 38 79 150 305 460 870 1400 2500 5100125 34 72 130 275 410 780 1250 2200 4500150 31 64 120 250 380 710 1130 2000 4100

175 28 59 110 225 350 650 1050 1850 3800200 26 55 100 210 320 610 980 1700 3500

Note: Use multiplier below for other gravities and pressure drops.

Table 2. Specific gravity other than 0.60

SPECIFIC GRAVITY MULTIPLIER0.50 1.1000.60 1.0000.70 0.9360.80 0.8670.90 0.8161.00 0.775

PROPANE-AIR1.10 0.740

PROPANE1.55 0.622

BUTANE2.00 0.547

Table 3. Pressure drop other than 0.3"

PRESSURE DROP

MULTIPLIER PRESSURE MULTIPLIER

0.1 0.577 1.0 1.830.2 0.815 2.0 2.580.3 1.000 3.0 3.160.4 1.16 4.0 3.650.6 1.42 6.0 4.470.8 1.64 8.0 5.15

6 IM 684-2

Gas Piping Routing Into UnitOn-The-Roof Piping (Models 020-140)1. Remove knockout (1) at corner of burner vestibule door

and saw out corner of door. See Figure 3b. Make saw cuts(2) tangent to round hole and square with door edges.

2. Install pipe corner plate (3) on vestibule, locating on pre-punched holes. See Figure 3c. This part is shipped insidethe vestibule.

3. Route gas supply pipe through hole. Carefully plan piperoute and fitting locations to avoid interference withswinging of doors, etc.

Typical Piping Connections

Figure 4.

Through-The-Curb Piping (Models 020-140)1. Remove bottom access panel (5). See Figure 3c.

2. Remove knockout (4) and make an opening (6) throughbottom deck directly below knockout hole.

3. Route gas pipeline through these openings and sealthem off with suitable grommets (7). See Figure 3a Section A-A.

4. Replace bottom access panel (5).

2

1

7

7

4

6A

A

See Figure 3cGas Supply

Section A-A

34 5

2

D

C

A

D

C

A BEWith Shutoff Cock

Folded backWith Shutoff Cock

In Front

F

Figure 3a.

Figure 3b.

Figure 3c.

Figure 4A Figure 4B

A = Shutoff Cock (ball valve)B = Union - Furnished.C = Gas Pipe - Routed in through frontD = Gas Pipe - Routed in through curbE = Factory Piped Gas TrainsF = Pilot Gas Tubing

IM 684-2 7

accessible from outside the unit, that valve must be relocatedor an additional valve added. In locating such a valve it is to bereadily accessible and located such that no obstructions inter-fere with operation of the handle. See Figure 16a, "Valve andRegulator Venting" and "Normally Open Vent Valves".

Condensate Drain (Models 020 and 025)Models 020 and 025 are equipped with a 3/4" I.P. condensatedrain pipe projecting from the back side of the furnace section(see Figure 14). If applicable codes or regulations require, thiscan be trapped and/or routed to a drain.

Vestibule (Models 150 Through 200)These two furnace sizes exceed the allowable shipping widthand for this reason the burner is disconnected and removed forshipment. A sheetmetal vestibule weather enclosure is also dis-assembled for shipment. At installation the burner must be re-mounted, the tagged electrical connections re-attached, and thevestibule re-assembled and mounted as shown in Figure 5.These items are packed in a crate and shipped as a separate item.

Gas Piping (Models 150 Through 200)The gas piping cannot be routed up to the burner fromwithin the curb on Models 150 through 200. Gas pipingmust be routed across the roof to under the burner vesti-bule, or a pitch pocket can be provided there. The installermust cut a hole in the bottom panel of the overhangingburner vestibule through which to route the gas line up tothe burner gas train. The bottom panel of the vestibule isat approximately the same elevation as the top of the curb.

Gas Piping Within The VestibuleThe gas piping layout within the vestibule will varyaccording to the complexity and size of the gas train rela-tive to the available room within the vestibule. As anexample, a gas train with a high pressure regulator and anextra safety shutoff valve (when required for IRI, etc.) willrequire careful use of the available space. The examplesshown indicate typical piping layouts.

Field Gas Piping RequiredThe gas train components have all been factory installedand require only a connection to the supply gas line. Themanual shutoff valve is located within the burner vesti-bule. If local codes require a manual shutoff valve that is

Figure 5.

Cut Gas Line Opening

Hinge

Side PanelDoor

Top Panel

Side Panel,With Latch

Bottom Panel

#10 Screw

Door

Fasten Wind DeflectorTo Door With #10 Screws,(Door & Wind DeflectorPart of Vestibule Kit)

8 IM 684-2

Start-up & Operating Procedures Start-up ResponsibilityThe start-up organization is responsible for determining thatthe furnace, as installed and as applied, will operate withinthe limits specified on the furnace rating plate.

1. The furnace must not exceed the specified "MaximumMBH Input." See "Verify Input Rate."

2. The furnace must not operate at an airflow below thespecified "Minimum Airflow CFM." On variable air vol-ume systems it must be determined that the furnace willnot be operated if or when system cfm is reduced belowthe specified minimum airflow cfm.

3. It must be established that the gas supply is within theproper pressure range. See "Gas Pressure Requirements."

Start-up ProcedureOnly qualified personnel should perform the start-up andservice of this equipment. It is highly recommended that theinitial start-up and future service be performed by McQuaycertified technicians who are familiar with the hazards ofworking on live equipment. A representative of the owner orthe operator of the equipment should be present during start-up to receive instructions in the operation, care and adjust-ment of the unit.

Before Start-up1. Notify any inspectors or representatives that may be

required to be present during start-up of gas fuel equip-ment. These could include the gas utility company, citygas inspectors, heating inspectors, etc.

2. Review the equipment and service literature and becomefamiliar with the location and purpose of the burner con-trols. Determine where the gas and power can be turnedoff at the unit, and before the unit.

3. Determine that power is connected to the unit and avail-able.

4. Determine that the gas piping, meter, and service regula-tor has been installed, tested, and ready to go.

5. Determine that proper instruments will be available forthe start-up. A proper start-up requires the following:voltmeter, manometer or gauges with ranges for bothmanifold pressure and inlet gas pressure, keyboard dis-play module or a 20K ohm/volt meter for flame safe-guard, signal strength measurement, C02 indicator,carbon monoxide indicator, and a stopwatch for timingthe gas meter.

WARNING

Should overheating occur or the gas supply fail to shutoff, turn off the manual gas valve to the appliance beforeshutting off the electrical supply.

Start-up PreliminaryClose main and pilot gas cocks. Install a keyboard displaymodule or connect a 20K ohm/volt meter to the test jack onthe flame safeguard. See Figure 6a.

1. Check the burner fan wheel for binding, rubbing, or loosesetscrews. Inspect the air damper and gas valve linkagesfor binding and check the linkage fasteners for tightness.

2. Check power. Position control switch on burner panel toAUTO. The POWER LED on the flame safeguard shouldcome on and after 10 seconds the burner motor shouldstart. Check for CCW rotation as viewed through blowerhousing inlet. If motor does not start, press the reset but-ton on the flame safeguard. If motor still does not start,consult the appropriate section of the troubleshootingguide. Continue on to Item 3 when burner motor will runwhen the switch is positioned to AUTO.

3. Check voltage. With the switch at AUTO, measure thevoltage across flame safeguard terminals 5 and L2. If it isnot between 108 and 132 volts, check the voltage andtapping connections to the supplying transformer at theunit's main control panel.

4. Purge the gas lines. Close the main gas valves and turnthe electrical switches off. Disconnect the pilot gas tubeat the pilot pressure regulator and bleed the gas line of allair. Close the pilot cock and reconnect the pilot tubing.

5. Leak check. Using a rich soap-water mixture and a brush,check the gas lines for leaks. Correct all leaks beforestarting burner.

Figure 6a. RM7895A Flame Safeguard

IM 684-2 9

Low Fire StartModulating burners are controlled for low fire start. Themodulating gas valve actuator will position the gas valve tothe low fire position each time the burner is to light off.

Pilot Start-upOpen the pilot gas cock (gas test cock remains closed) andposition the switch to AUTO to start the burner motor. After30 (or 90) seconds the pilot valve opens (as indicated whenthe indicator LED marked PILOT comes on) and the pilotshould ignite. The flame signal should read 1.5 to 5.0 voltsDC. The LED marked MAIN should come on when the pilotflame has been detected by the flame safeguard and it hasenergized the main gas valve. On the initial start-up, if thepilot does not light and the flame safeguard locks out, reset itand make several attempts to light the pilot before assumingproblems other than more air in the gas lines. If the initialpilot operation is erratic, it may be well to wait until after aperiod of main flame operation has further purged the gaslines before trying to "adjust out" something that may actu-ally be air in the lines. If the burner is equipped for modula-tion or two-stage operation, observe the flame signal readingat all firing positions. Cycle the flame safeguard to determinethat the burner goes to the low fire position for light off andthat the pilot will ignite and operate. See "Service" sectionfor pilot adjustments, etc.

Main Flame Start-up1. At the conclusion of the pilot start-up and with the gas test

cock closed, measure the air box pressure (see Table 5)by holding a rubber manometer tube tightly over theburner air pressure port (5), Figure 16A. The tube mustsurround the hole and seal tightly against the door to mea-sure the static pressure through the hole. Modulatingburners are to be at their "high fire" position for this mea-surement. Table 5, Column 8, indicates typical readingsand any appreciable deviations from these would indicatea burner air problem that should be found before attempt-ing to fire the unit. These problems could include linkageadjustments disturbed during shipment, etc.

2. With control switch at OFF, connect the manometer to themain manifold pressure tap (9), Figure 16A, and open thegas test cock.

3. Position the switch to AUTO and the unit will go throughthe prepurge cycle, the pilot will light, and the main flamewill come on. Watch the manometer during the light offattempt. The manifold pressure should rise to about 90%of the specified value within 2 seconds and the mainflame should ignite immediately when the pressureapproaches this value. If the burner has not lit within afew seconds after pressure is indicated on the manometer,shut down the unit and check for problems (refer to Trou-bleshooting chart). Modulating burners should have theircontrollers set to call for high fire although they will havea forced low fire start. If combustion appears normal, pro-ceed with combustion tests.

4. Combustion tests. These tests should be run after the fur-nace has been running 10 to 15 minutes.

a. Check input: See Verify Input Rate

b. Check CO2 ; See Check C02, CO & Stack Temperature

c. Check CO; See Check CO2, CO & Stack Temperature

5. On modulating burners cycle the burner from high to lowfire, observing flame and repeating CO2 and CO tests atlow fire after burner has been running 10 to 15 minutes.

6. Cycle the unit through several start-ups with controls call-ing for first low fire and finally high fire, being alert forany hints of trouble or unexplained inconsistencies thatcould indicate future problems.

Typical Sequence of OperationOn-off gas burner (see Figure 6b):When burner is to operate, line 878 from main control panelis energized (120 volt). Line 878 feeds through the Burnerswitch (S3) on the burner control panel to power terminal 5and through the normally closed contacts on the high limitcontrol to energize terminal 6 on the RM7895A. When termi-nal 6 is energized a 10 second "Initiate" sequence will run,after which terminal 4 becomes energized and starts theburner blower. Blower operation is sensed by the combustionair switch which makes 7 to 6 and the prepurge period begins.At the end of the prepurge period (30, 60 or 90 seconds), ter-minals 8 and 10 are energized, opening the pilot gas valveand energizing the ignition transformer. After the pilot flameignites and is detected by the flame rod, terminal 9 is ener-gized, opening the main gas valve, and terminal 10 is de-energized, shutting off the ignition transformer.

In the event the pilot fails to light, or fails to prove itselfwithin 10 seconds, the RM7895A will go on safety shutdownand require manual reset.

Modulating gas burner without end switch cycling:Similar to ON-OFF operation described except, at any timethe burner is operating, the modulating controllers will deter-mine the firing rate. The modulating controls position anoperator which will change both gas and airflow proportion-ally. The modulating control will always go to the low fireposition for light off.

10 IM 684-2

Figure 6b. Typical electrical schematic with RM7895A

Figure 7. Piping Schematic

IM 684-2 11

ServiceGeneral (see Figure 16C)The McQuay gas burner has a pre-mix pilot burner. Thepilot pressure gauge tap (2) is a capped 1/4" flare male con-nection which can be connected to a manometer to measureboth pilot air and gas pressures. Thus, these adjustments canbe accurately made and checked with instruments. Thismanometer connection is also useful in troubleshooting thepilot. Failure of the pilot pressure regulator, pilot gas valves,and plugged or improper gas or air openings are easily diag-nosed with the manometer.

Pilot Air & Gas Adjustments (see Figure 16, Items 1 & 2)A manometer connected to the pilot pressure gauge tap (2)will indicate pilot air pressure when the pilot gas valve isclosed, as during the prepurge period, and will indicate gaspressure on the pilot orifice when the pilot gas valve is open.Thus both readings are taken from this one test connection.

1. Connect manometer to pilot tap (2).

2. While the burner fan is running, the pilot gas valve isclosed, and the modulating burner has its air damper atthe low fire position; read the pilot air pressure. Typicalreadings are shown in column 5 on Table 5.

3. At the completion of the prepurge period the pilot valvewill open and the manometer will then read pilot gaspressure. Typical readings are shown in column 7 onTable 5.

4. Pilot flame signal readings should be 2.5 to 4.0 volts DCand steady at the low fire position when only the pilot isoperating. When the main burner flame is also burningthe readings will be higher.

5. A single stage burner that does not have low fire start,and always operates at "high fire" should have pilot flamesignal readings of 2.0 to 3.2 volts DC and steady whenonly the pilot is operating. When the main burner flame isalso burning the readings will change.

6. The pilot gas and pilot air pressure readings shown inTable 5 are typical. The pilot gas and pilot air pressureshould be adjusted for optimum flame signal, not to agreewith the values shown in Table 5.

7. Vary the pilot gas pressure regulator and find the mid-point of the peak gas pressure that produces the highestpilot flame signal voltage. The voltage should decrease asthe pressure is either decreased or increased beyond thatpeak. If peak midpoint voltage was obtained at gas pres-sures below 3.0 Inches W.C., this would indicate morepilot air is required and there is a problem with the pilotair pickup tube. The pickup may be out of adjustment,kinked, or damaged so it is not providing adequate air tothe pilot.

8. If the pilot flame signal voltage is within the range speci-fied above, use that peak midpoint setting as the pilot gaspressure setpoint.

9. Determine that the pilot will hold in satisfactorily atBOTH high and low fire on modulating burners. Test thisby observing the flame signal as the burner repositionsfrom low fire to high fire.

10.The flame safeguard has a 10-second trial for ignitionperiod. A properly operating pilot will light and proveitself to the flame safeguard within one second. If it takeslonger than one or two seconds to prove pilot flame thepilot is probably too lean and a higher pilot gas pressureregulator adjustment is required.

Pressure RegulatorApproximate pilot gas pressure adjustments can be madeeven when a manometer is not available. Snug the regulatoradjusting screw to the bottomed out position and back out 2-1/2 turns for 4.0"W.C., three turns for 3.7"W.C., 3-1/2 turnsfor 3.2"W.C., or 4 turns for 2.9"W.C.

Pilot Orifice (see Figure 16C, Item 9)The pilot orifice is threaded into the pilot test tee (8) whichmust be removed to get access to the pilot orifice, for orificedrill size, see Table 5.

Ignition Electrode Adjustments (see Figure 8a)The ignition electrode should be adjusted per Figure 8a. Thepurpose of the porcelain bushing is to provide an air seal thatprevents air from blowing into the pilot burner through theignition electrode hole. Because the bushing provides an airseal it must be in close contact with the countersunk surfaceon the pilot burner, and gently held in place by the spring.The bushing should be perpendicular to the hole.

The electrode tip should be centered within the .25 inchhole and be flush with the inside surface of the pilotburner or project up to .03 inches into the burner. Theignition spark occurs between the electrode tip and theedge of that .25 inch hole, to the point on that hole that isclosest to the electrode. If the electrode is not centeredthat closest point results in a shorter spark gap and con-sequently less of a spark to ignite the pilot. The springwill allow the bushing to be slid back from the hole toget a better view to check the electrode tip centering.Good alignment and fit may require slight repositioningof the electrode within the clamp and/or bending theclamp by gripping the electrode clamp with a pliers.Both ends of the bushing are the same. If the end thatmates with the pilot burner gets damaged or if there is animperfection in one end, the bushing can be reversed.

Flame Rod Adjustment (see Figure 8b)The flame rod should be adjusted per Figure 8b and suchthat flame rod shaft is not shorted against gun discs or pilotburner.

Pilot Location Adjustment (see Figure 9)The location of the pilot burner relative to the openingthrough the gun discs can be adjusted by bending the pilotbrackets. Improper adjustments can result in rough light off.The flame rod must also be adjusted such that it does notshort against the gun discs.

12 IM 684-2

.00 to .03

PorcelainBushing

Spring

.25

.32

Flame RodAdjustment

Igition ElectrodeAdjustment

Figure 8a. Figure 8b.

Figure 9a. Figure 9b.

.06

.06 .06

Flush

Center PilotTo Cutout

Models 320 thru 2000

CL

.09

Models 200 thru 250

Air Pickup Tube Adjustment (see Figure 10)The proper location for the tube is indicated in Figure 10.When changes in the pilot air pressure are required, the pilotair pickup tube can be repositioned. Tipping the tube furtherinto the airstream (increasing angle M°) will increase thepilot air and bending it more perpendicular to the airstream(decreasing angle M°) will decrease the pilot air. If the tubeis kinked or flattened, pilot air is reduced. This can lead tounstable pilot operation and nuisance tripping of the flamesafeguard. Once kinked, the tube will probably have to bereplaced.

Figure 10.

A.38

A20°

1.00

Pressure Switch Sensing Tube

Pilot Air Pickup Tube

Section A-A

M°

M = 20° Models 020 thru 100M = 10° Models 110 thru 200

Gun AssembliesThe McQuay gas burner has an easily removable gun assem-bly which includes the complete pilot burner assembly andthe main flame burner head. The positioning of this assem-bly within the burner blast tube determines the shape of theflame. This is adjusted at the factory and normally would notrequire readjustment in the field.

The burner discs must be perpendicular to the blast tube tohave a symmetrical flame. The discs must not be positionedforward into the conical portion of the blast tube. Movingthe discs toward this conical portion of the blast tube spreadsthe flame and moving the discs farther back into the cylindri-cal portion of the tube lengthens and narrows the flame.

Figure 11.

(Dimensionson Figure 16)

A

IM 684-2 13

In general, if the discs are located too far back in the blasttube, uneven heat distribution will result. The back of theexchanger will get too hot and the front will remain cool.Rough light off of the main flame can also result. If the discsare located too far forward, the widened, shortened flamewill cause the front of the exchanger to get too hot, and theback will remain cool. Poor combustion can also result, aswill be indicated by a CO test.

The gun assembly can be adjusted forward and backward byfirst loosening the three bolts on the bracket where the gaspipe enters the burner box. Other adjustments are made bytightening the pipe fittings in the gun assembly.

Modulating Linkage AdjustmentAll burners are factory adjusted and test fired prior to ship-ment and therefore at most should require only minor adjust-ments. The dimensions given for linkage adjustments,etc., are intended to serve as a guide when replacing com-ponents. It is not intended that on start-up the servicetechnician will go through the burner and readjust devia-tions to these dimensions.

Procedure (see Figures 16a and 16b):1. Adjust firing rate positioner crankarm. Side of swivel to

edge of slot equals B.

2. Adjust "positioner to valve" pushrod to dimension C,clamp to clamp.

3. Adjust "valve to air damper" pushrod to dimension D.

4. Adjust air damper arm length to dimension E.

5. With the firing rate positioner at its minimum fire posi-tion, tighten the air damper arm to arm damper shaftwhile the damper blade is positioned to opening F.

6. Adjust the air damper side fills for minimum gap alongthe side of the air damper blade. Do not adjust so tightthat the blade binds or scrapes.

7. Adjust slide damper to dimension H.

8. If all these adjustments have been made to these specifi-cation, the air damper end opening should be F at theminimum fire position and G at the high fire position.

9. Finally, fine tune these adjustments with instruments.Connect a manometer to the tap on the manifold to mea-sure gas pressure at the orifice. When the modulatingoperator is positioned to the minimum fire position andthe burner is operating, readjust C to obtain the specifiedminimum fire gas pressure on the orifice. Typical: .44 in.W.C. natural gas. Readjust D to obtain an even, quietflame and the specified CO2 and CO.

10. Reposition modulating operator to high fire position andadjust the pressure regulator to specified manifold pressure.

Combustion TestingProper start-up and maintenance requires periodic combus-tion tests and the systematic recording of those test resultsfor future reference. Before making combustion air adjust-ments, check for proper input rate.

Verify Input RateTo determine the input rate it is necessary to know the BTUper cubic foot of gas being used. If this is not known, contactthe gas supplier. Check input rate by timing the gas meterdial with all other appliances and their pilot lights off. If1000 BTU/cu. ft. gas is being used the input can be verifiedusing Table 5, the measured manifold pressure, and check-ing the orifice drill diameter.

To verify the input rate using the gas meter, use a stopwatchand time one revolution of the dial. Calculate the input withthe following formula:

MBH Input = A x B x 3.6 C

Where: A = BTU/cu. ft. of gas Typical: Natural gas= 1000, LP gas=2500B = Cu. ft. per revolution of meter dialC = Seconds required for 1 revolution of meter dial

Check CO2, CO & Stack TemperatureFlue gas samples are to be taken from inside one of the sec-ondary tubes. If the sample is taken from the flue box ratherthan the tube, the sample will be diluted with outside air andlower readings will result. If flue gas temperature is to bemeasured, this must be done in the flue box, not in the tube.The temperature gradient within the tubes would cause highreadings near the center of the tube and low readings near theedge. Temperatures should be measured within the flue boxwhere a good mix will be present. The flue box includes two5/16" holes for test purposes. One hole lines up with the endof a secondary tube for taking flue gas samples. The otherhole, through the side of the flue box, is for thermometerinsertion.

If the CO2 and/or CO readings are not within the range indi-cated, see "Troubleshooting Chart," Section 41 and 42.

Figure 12a. Figure 12b

300º400º500º

600º

Temperature Gradientwithin Tube

Co2Sample

MeasureTemperature

14 IM 684-2

Typical Readings:CO2 9½ to 10½ percent at maximum rate 9 to 10 percent at minimum rate

CO .001 percent (10 PPM) or less

Cleaning Heat ExchangersModels 032 thru 200 (see Figure 13)

1. Remove the flue box front wrap (1) and the rear inspec-tion cover (3).

2. Remove and clean the turbulator (2) from each tube andclean the flue box.

3. Clean each tube with a 2-1/2" round flue brush.

4. Remove the brushings and if required clean the combustionchamber and header through the rear inspection door port.

5. Reinstall the inspection door (3) . Snug the screws but donot overtighten and crush the insulation.

6. Reinstall a turbulator in each tube approximately flushwith the tube ends, locking them in place with the wedgeclip on each turbulator.

Figure 13. Models 032 thru 200 heat exchanger

Leakage Symptoms1. Odor - Odors in the building are usually being brought in

through the outdoor air intakes and do not indicate leak-age from the furnace. Check for down draft conditionsand check for location of the flue exhausts of other equip-ment that may be pulled into the outdoor air intake. Amajor and obvious furnace rupture can be a source ofodor. In general, small leaks in a furnace will not be asource of odor or danger because the pressure created bythe supply fan is greater than the pressure inside the fur-nace. Therefore when the supply fan is operating, leakagewill be into the furnace, not out of the furnace and intothe air stream. If the control system is such that the fur-nace comes on and warms up the heat exchanger beforethe supply air fan comes on, and there is odor when thesupply fan first comes on, this could be caused by leak-age. During the time the furnace is on and the supply fanis off the leakage would be out off the furnace and thenwhen the supply fan came on it would blow those prod-ucts of combustion into the supply duct.

2. Low CO2 Readings - Low CO2 readings that cannot becorrected can be caused by air leaking into the heatexchanger and diluting the flue gas. If this is suspected,take two consecutive CO2 readings, one with the supplyfan running and one with the supply fan off. If the CO2increases with the supply fan off, it could indicate leak-age. Note that CO2 samples must be taken from inside atube, not just from inside the flue box.

Checking For Leaks1. Open up the rear casing panel while the unit is shut off

and visually inspect the heat exchanger.

2. Visually inspect the heat exchanger while the burner isoperating, looking for light coming through holes. Theburner should only be operated for a few minutes with thesupply fan off, and take necessary safety precautionsaround the hot heat exchanger.

3. Perform consecutive CO2 tests with supply fan off andon. See Item 2 under "Leakage Symptoms."

3

2

1 2 1/2 Round Flue Brush With 7 Foot Handle

Models 020 thru 025 (see Figure 14)1. To gain access to the inside of the combustion chamber,

detach the burner from the furnace and set it on the floor ofthe vestibule (see Figure 14, Item (3)). The burner isattached to the furnace studs with four nuts. Conduit lengthsallows this movement of the burner without disconnectingwiring. The union on the gas line must be opened.

2. Remove the flue box front wrap (1).

3. Remove and clean the turbulator (2) from each tube andclean the flue box.

4. Clean each tube with a 2-1/2" round flue brush.

5. Remove the brushings and if required clean the combustionchamber and header through the burner mounting tube.

6. Reinstall the burner.

7. Reinstall a turbulator in each tube approximately flushwith the tube end, locking them in place with the wedgeclips on each turbulator.

3

2 1/2 Round Flue Brush With 4 Foot Handle

2

1

Condensate Drain

Wind Deflector

Figure 14. Models 020 thru 025

IM 684-2 15

4. Smoke Bomb Test - Cover the flue box openings, openthe rear casing panel so the heat exchanger is accessible,toss a smoke bomb into the heat exchanger through therear inspection port, replace the port cover, and with abright light look for smoke leaking through the heatexchanger. Remove the remains of the smoke bomb anduncover the flue box openings before attempting to oper-ate the furnace.

Note: In most cases small leaks in the heat exchanger arenot a source of danger. Because the pressure createdby the supply fan is greater than that inside the heatexchanger, the leakage wil l be into the heatexchanger, not out of the heat exchanger and into theairstream.

Causes of Failures1. Improper Application - The furnace rating plate speci-

fies a "Minimum Airflow CFM." The furnace must not beoperated when airflow is below this minimum cfm. If thefurnace is being used on a variable air volume system, thecontrol system must be such that the furnace will notoperate when the supply fan cfm has fallen below thisminimum specified cfm. The furnace rating plate alsospecifies a "Maximum MBH Input" which must not beexceeded. See "Verify Input Rate."

2. Control Failure - The limit control does not functionproperly and shuts off the burner when the heatexchanger temperature becomes excessive. In most situa-tions, a properly controlled unit will never even requirethe limit control to shut off the unit. The limit controlshould be a backup control and a problem attributed to alimit failure would generally indicate a control problemin addition to the limit failure.

3. Excessive Condensation - Applications which will pro-duce condensation require an all stainless steel heatexchanger to be resistant to the effects of this condensa-tion and to give long heat exchanger life. The likelihoodof condensation increases with:

a.Colder supply air temperature across the secondarytubes, as on units taking in a lot of outdoor air in colderweather.

b.Lower heat flow through the secondary tubes, as onmodulating burners when operating at reduced input.

c.High airflow across the secondary tubes such as anyapplication with a low temperature rise furnace.

4. Chemical Deterioration - Refrigerant leaks, some aero-sol can propellants, fumes from dry cleaning establish-ments, beauty shops, swimming pools, and others, oftenhave detrimental effects on heat exchangers when theyget into the combustion air supply and thereby into thecombustion. Even fumes from nearby roof exhaust fanscan cause problems.

5. Inadequate or Distorted Airflow - Internal baffles thathave been repositioned or have loosened up and moved

can distort the airflow and cause failures. Constructionrubbish, shipping cartons, and insulation that has comeloose will occasionally end up inside a unit and blockairflow to part of the furnace, resulting in a failure. Orthese items can alter the air or heat flow to the fan limit orsome other control and contribute to a failure.

Replacing A Heat Exchanger1. Remove the complete flue box, the casing panel through

which the flue tubes pass, and the rear inspection cover.Open the hinged rear door.

2. The burner is mounted on and supported by the heat exchangerstuds with four nuts. When removing the heat exchanger, theburner must either be removed or blocked in place. Removethe four burner mounting nuts and the two exchanger boltslocated 2" above the upper burner mounting nuts.

3. When it is necessary to remove any air bafflessurrounding the heat exchanger, carefully note thelocations and clearances of these baffles before removingthem so they can be replaced in the exact same position.

4. Remove the two bottom bolts at the back of the heat exchanger.

5. Withdraw the heat exchanger through the back of the casing.

Furnace Condensation A furnace will produce condensation when the flue gas tem-perature falls below its dew point temperature. A more effi-cient furnace will transfer more of its heat into the building,and leave less heat in the flue gas. This results in a lower fluegas temperature and more condensate.

A modulating burner will produce more condensate than anon-off burner. As the firing rate of the burner is reduced theflue gas temperature will be reduced, and more condensatewill be produced.

A furnace that is heating a high percentage of outside air willalso produce more condensate. The colder the air contactingthe heat exchanger, the lower the resulting flue gas tempera-ture, and consequently the more condensate.

Do not think a furnace has a problem because it produces conden-sate anymore than you would think a cooling coil has a problembecause it produces condensate. However suitable steps should betaken to manage the flow of the condensate produced.

Most condensate will be produced in the secondary tubeswhere flue gas will sweep it into the flue box. Condensatewill also come from the combustion chamber. Models 020and 025 have a piped combustion chamber condensate drain,and Models 032 through 200 have a rear cleanout port withan integral condensate drain.

On a properly prepared unit, the condensate should drip fromdrain openings in the two outer corners of the flue box, andfrom the drip shield below the rear cleanout port. Condensateshould not be running down the unit, except at times thewind may blow the dripping condensate mentioned above.At installation the flue box should be seated with high tem-perature silicone (see "Installation - Flue Box, Item 3"). The

16 IM 684-2

drip shield below the rear cleanout port must be correctlyinstalled. See following section: "Rear Cleanout Port".

Rear Cleanout PortFigure 15a.The rear cleanout port is equipped with a stainless steel dripshield to channel the flow of condensate coming out thecleanout port (see Figure 15a). The shield (1) must fit snuglyagainst the bottom of the cleanout port tube (2) at (3) so con-densate (4) cannot run back along the underside of the tubeand into the unit or down the side of the rear panel. Instead,the condensate is to run down the drip shield and be directedinto the spout.

Figure 15a.

Furnace Condensate Drain KitFigure 15b.

Considerations:It is possible that condensate will freeze within the conden-sate drain tube and this should be considered, particularly ifplanning to extend the condensate drain tube beyond the ver-tical piece furnished. Freezing is influenced by the fact thatthe condensate leaving the furnace is hot, that it is accompa-nied by a discharge of hot flue gas, and that during coldweather the furnace will operate at a higher firing rate andmay not produce condensate.

If the tube does freeze and plug, condensation will then exitwhere the spout (1) enters the tube, and will run down fromthat point until the tube thaws open.

Install.875 Copper Drain Line1. A length of copper tube is furnished to route the furnace

condensate down the side of the unit to the roof or otherchosen location. The length of copper tube (2) furnishedwill extend approximately 2 inches below the bottom ofthe unit. The length can be trimmed or fittings added asrequired by field conditions.

2. The tapered stainless steel spout (1) at the bottom of therear inspection port slips approximately.25 inches into theupper end of the copper tube (2) . Bend the end of thespout out from the casing panel slightly so the tube can beslipped into position.

3. The copper tube runs vertically down the side of the unitand extends approximately 2 inches below the bottom ofthe unit base frame. The copper tube can drain onto theroof or drain into any means of condensate disposal thathas been provided.

4. The tube is attached to the door by a clamp (3) which usesa No. 10 x 1.50 Lg. stainless steel drill screw (4) . Thedrill screw hole is located 2.75 inches below the bottomof the inspection cover, with the exception that severalmodels are drilled at 3.15 inches below the inspectioncover to avoid the no drill zone.

Install the Cover Channel Over Drain Pipe1. Locate the copper channel (5) over the drain line. The top

of the channel should be approximately .75 inches belowthe bottom of the inspection cover and extend approxi-mately flush with or somewhat below the bottom of theunit base frame. The channel is positioned so the mount-ing screw holes are on the left.

2. The cover channel for certain models have an edge notch.This notch is to provide clearance for a bolt head in thebase frame.

3. Attach the channel with two No. 10 x 1.50 Lg. stainlesssteel drill screws (6). Pay close attention to the "no drillzones". There could be wiring in the lower zone, andthere is a door sealing gasket in the upper zone.

3

1

2

4

2

3

1

Figure15b. Condensate Drain Kit

.75

5

6

1

4

3

2

2.75*

1.45

.75.38

NO DRILLZONE

*SOME MODELS ARE3.15" TO AVOID NODRILL ZONE

IM 684-2 17

Combination Fan And Limit ControlThe fan limit control is a hydraulic action type with a remotesensing element and connecting capillary tube. The sensingelement is locked into a bracket located on one of the heatexchanger tubes about halfway toward the back of the fur-nace, on the side away from the blower. One corner of thebracket is bent aside to remove the element.

Normal setting of the FAN control: Fan On=125°F., FanOff=100°F.

The LIMIT control must never be set higher than the belowlisted temperature. If the burner is shutting off on high limitat these settings it indicates that there is a problem with thefurnace not getting enough air or it is being overfined.

Table 4. LIMIT control set points

MaintenancePreventative maintenance is the best way to avoid unneces-sary expense and inconvenience. Have this system inspectedat regular intervals by a qualified service technician. The ser-vice intervals below are typical for average situations butwill have to be adjusted to suit your particular circumstances.

Fuel pressure settings, control settings, and linkage adjust-ments should only be made by persons thoroughly experi-enced with the burner and control system and should not betampered with by persons without such experience.

Always replace covers on burner controls and boxes as theelectrical contacts are sensitive to dust and dirt. Maintenanceof flame safeguard, controls, gas valves, and other such com-ponents should be performed in accordance with instruc-tions contained in the manufacturer's bulletins.

Monthly1. Check air filters and main supply fan drives, replacing if

required.

2. Check flame signal with a DC voltmeter.

Twice Yearly1. Burner Air - Check burner fan wheel for dirt buildup and

lint. Check combustion air intake louver and flue box fordirt buildup and accumulation of windborne debris.

2. Cleaning - Inspect flue tubes and combustion chamber,cleaning as required. Keep burner vestibule clean. Dirtand debris can result in burner air blockages.

BURNER MODEL LIMIT CONTROL SET POINT

BURNER MODEL LIMIT CONTROL SET POINT

020 215 079 181025 160 080 229032 196 100 170040 154 110 222050 229 140 168064 185 150 194065 232 200 151

Yearly1. Gas Train - Check all valves, piping and connections for

leakage. Remove burner gun assembly. Inspect and cleanpilot burner, flame rod, ignition electrode, main burner discs,and blast tube. Check tightness of linkage fasteners and boltsthat could work loose from vibration and movement.

2. Combustion - Check quality of combustion. Test CO2and CO and look for irregularities in fire shape. Ifcombustion characteristics have changed since the lasttest, determine the cause. Changes in input changes in theBTU content of gas being supplied, reduced combustionair due to a dirty blower wheel, or flue passages in needof cleaning can all cause changes in CO2 reading. When areadjustment seems necessary, do not make theadjustment without first trying to determine if therequired change is not an indication that something else isin need of correction.

3. Flame Safeguard - Perform a flame failure check andpilot turndown test. See control manufacturer's bulletinfor further information.

4. Motor - Motor life will be increased by proper oiling.There are provisions in both end shields for relubrication.Re-oil each bearing with 150 drops (approximately 1teaspoon) SAE-20 oil.

5. If the burner is to be out of service for the summer, turn offthe burner control switch and close the manual gas cocks.

Flame SafeguardSee manufacturer's bulletin for more detailed information orfor information on flame safeguard other than the RM7895A.

The Honeywell RM17895A is a microprocessor based inte-grated burner control that will do self-diagnostics, trouble-shooting, and status indication, as well as the burnersequencing and flame supervision.

Keyboard Display ModuleThe Honeywell S7800A1001 module is an optional deviceavailable for use with the RM7895A. It can be a permanentaccessory added to the RM7895A or it can be carried by theservice technician as a tool that is very easy to mount whenservicing the RM7895A. It mounts directly onto theRM7895A and has a 2 row by 20 column display. The modulewill indicate flame signal dc volts, sequence status, sequencetime, hold status, lockout/alarm status, total hours ofoperation, total cycles of operation, and can provide 127different diagnostic messages for troubleshooting the system.

The module will give a fault history. It can be mounted to theRM7895A and will retrieve information on the six mostrecent faults.

Consult the Honeywell bulletin 65-0090-1 "7800 Series,Keyboard Display Module" and 65-0118-1 "7800 Series,System Annunciation, Diagnostics and Troubleshooting".

18 IM 684-2

OperationInitiate Period: When the relay module is powered it goesthrough a 10 second "Initiate" period. It will also enter intothe "Initiate" period if electrical power problems such as lowvoltage or momentary interruption occur while the unit isoperating. Operation of the burner fan motor is delayedthroughout the "Initiate" period.

Standby: After the initiate period is completed the modulewill enter the standby and await a call for heat by the tem-perature control system.

Normal Start-upPrepurge: Upon a call for heat the prepurge period willbegin. If the air switch does not detect fan operation by 10seconds into the prepurge a recycle to the beginning of theprepurge will occur.

Ignition Trial: The pilot gas valve and the ignition trans-former are powered for 10 seconds following the prepurge.Pilot flame must be proven at the end of that 10 secondperiod or safety shutdown will occur.

Run: If Pilot flame is proven at the end of the 10 secondignition trial the main gas valve will be powered. If a flame-out occurs the module will recycle within 3 seconds, and ini-tiate a new prepurge period. If pilot flame continues to bedetected the module will be in Run until the power is inter-rupted to terminal 6 indicating that the temperature controlsystem no longer requires heat, or that the high limit oranother safety control has opened.

LED DisplayThere are five labeled LED's located on the front of theRM7895A which are energized to indicate operation as fol-lows:

POWER The RM7895A is powered

PILOT The prepurge period is complete and the terminalfor the pilot gas valve is powered.

FLAME Pilot flame is detected.

MAIN The ignition trial period is complete, flame isdetected, and the terminal for the main gas valveis powered.

ALARM The RM7895A is on safety lockout.

IM 684-2 19

Troubleshooting ChartThe RM7895A flame safeguard is equipped with five LEDs toaid in the diagnosis of burner operation and problems. In addi-tion, a Keyboard Display Module is available and is a valuableaid for indicating flame signal DC volts, fault messages,sequence status, etc. See "Flame Safeguard (RM7895A)" foradditional information on the Keyboard Display Module andfor a description of the function of the LEDs.

Some of the steps listed in this troubleshooting chart will beunnecessary if a Keyboard Display Module is used, as thatmodule will pinpoint many problems.

Voltage checks can be accomplished without removing theFlame Safeguard by removing the "Electrical Access SlotCovers" on the side of the sub-base and then using thoseelectrical access slots.

BURNER MOTOR DOES NOT RUN (AFTER 10 SECOND "INITIATE" PERIOD AND WITH SWITCH AT AUTO):

1.1 Power LED is off. a. Power is not getting to burner.

1.2 Entire unit seems to be off. a. Burner power comes from the main control panel which has a main disconnect switch, a stepdown transformer with primary winding fuses, a 120V secondary winding fuse, and an on-off service switch. If any of these were open, the burner as well as the supply fan would be inoperative. The control system also has firestat type temperature sensors which will shut down the entire unit if supply or return air temperatures exceed set points. On some control systems the firestats only lock out the sup-ply and return fans. Check main control schematic as these would not be burner problems.

1.3 Supply fan will operate. a. Check the manual reset limit control located between the filters and the supply fan and reset if required.

b. Check that the control system has energized relay R20 located in the main control panel.

1.4 Power LED is on. a. Push the reset button on the flame safeguard.

1.5 Resetting flame safeguarddoes not start motor after the 10 second "Initiate" period is completed.

a.Push the reset button on the burner motor. (Note: If motor is hot and probably tripped, it has to cool sufficiently before it can be reset.)

b.Remove the left side electrical access cover on the flame safeguard sub-base and test for line voltage at terminal 4and L2. If powered, the problem is with the burner motor or its associated controls. On Models 1100-2000, terminal 4 only controls a contactor and burner motor power comes from its own circuit breaker. If terminal 4 is dead, check for power to terminals 6 and L2.

c.IF VOLTAGE IS ZERO: The power is being interrupted by the limit control, the manual reset high or auto reset low gas pres-sure switches (if included), the low fire end switch on the modulating operator (if included), or relay contact in the main control system. Consult the schematic and determine the interruption.

d.If voltage is satisfactory at terminals 6 and L2 and terminal 4 does not become energized after 10 seconds, and pressing the safety reset button has no effect, replace the RM7895A.

BURNER MOTOR RUNS, BUT...

2.1 Burner motor runs continu-ously, but burner does not start (pilot LED) does not come on after 30 (60 or 90) seconds.

a. The air switch sensing tube is not in the blower housing and sensing pressure.

b. The air switch or its wiring is defective. 120 volts should appear between terminals 7 and L2 if airflow switch contacts are made.

2.2 Burner motor starts when the reset button on RM7895A is pressed. The motor runs for 40 (70, 100) seconds and then the burner shuts down and requires manual resetting.

a. If the PILOT LED did not come on for the 10 seconds before shutdown check for voltage between terminal 10 and L2 during the final 10 seconds before control locks out on safety. If zero voltage, replace the RM7895A.

b. If the PILOT LED did come on for 10 seconds before shutdown the pilot flame is not igniting or is not being detected by the flame safeguard. Check that the manual gas valves are open.

c. Check the flame safeguard with a flame simulator.1. Close the main gas test cock.2. Plug the flame simulator into the flame safeguard.3. When the pilot indicator light comes on, touch the simulator G post to ground. If the FLAME LED now comes on the flame safeguard is working, but it is not receiving an adequate flame signal. If the FLAME LED did not come on replace the R7847A amplifier or/and the RM7895A.

2.3 During the 10 second period before shutdown there is:

a. Close the main gas cock (pilot gas cock open) and observe the pilot through the inspection window as it goes through a sequence.

2.4 No spark or flame. a. Remove the burner gun assembly and check for shorted ignition electrode, open ignition lead, defective ignition transformer, or loose terminal screw on flame safeguard subbase. Check for voltage between terminal 10 and L2 during the final 10 sec-onds before the control locks out. If zero voltage, replace the RM7895A.

2.5 Spark but no flame. a. Improper pilot and gas adjustments. Connect a manometer to the pilot test tee and adjust per 'Pilot Air and Gas Adjustments" section. If the specified settings cannot be attained a problem is indicated.

2.6 Improper pilot air readings. a. The pilot air pickup tube is not inserted into the blower housing, is broken, cracked, kinked, or improperly positioned.

b.Plugged air tube.

c.Tubing to the pilot burner is not connected, is loose or cracked.

d.Plugged pilot gas orifice.

2.7 Proper pilot air and gas readings, spark but no pilot flame.

a. Porcelain sleeve around ignition electrode is not adequately reducing airflow through this opening. See "IgnitionElectrode Adjustment" section.

b. Air in gas lines as a result of inadequate bleeding or recent service work or construction.

c. Readjustment of pilot air and gas is required. Refer "Pilot Air and Gas Adjustment" section.

2.8 Pilot flame comes on, but flame safeguard still locks out.

a. The flame safeguard is not detecting pilot flame. Check flame safeguard using a flame simulator as described in 2.2-c. If this test confirms flame safeguard is working, and the pilot is coming on during the 10 second ignition trial period, then the pilot is not producing an adequate flame signal. Check pilot and its adjustments as listed above in 2.6-b, c and d.

b. Disconnected, shorted or open flame rod lead.

20 IM 684-2

MOTOR RUNS, PILOT IGNITES...

3.1 Burner motor starts. After 30 (60 or 90) seconds the PILOT LED comes on, theFLAME LED comes on momentarily and then goes out.

a. The power is only momentarily proving itself to the flame safeguard. It must be proven at the end of the of the 10 second igni-tion trial.

b. On a new start-up this could indicate the gas lines have not been sufficiently purged of air.

c. Improper flame rod position.

d. Improper pilot air or gas adjustments.

e. Air leakage into the pilot burner at the porcelain bushing or through cracks in pilot burner.

f. Defective or improperly installed pressure regulator upstream of pilot gas cock that passes enough gas for pilot, but when main valve opens, gas pressure drops drastically.

3.2 Pilot operates, the flame safeguard does not lock out. but the main flame does not come on.

a. Check that the main manual gas cocks are open.

b. If the Main LED does not come on, check the voltage at terminals 9 to L2. If no voltage across 9 to L2, replace the RM7895A.

c. Check for defective or improperly installed pressure regulators and determine that their vents are not plugged.

d. Check for defective or improperly installed main gas valves, or open wires to the valve.

e. On diaphragm type gas valves, check for plugged or misadjusted bleed orifice or bleed line.

BURNER OPERATES; HOWEVER ...

4.1 Main flame light off is rough.

a. The furnace is being fired above its rated capacity. See "Verify Input Rate."

b. Heat exchanger needs cleaning. Increased pressure drop through heat exchanger reduces airflow through burner and affects combustion.

c. At light off, the gas valve is opening too fast. On diaphragm type valves check the bleed orifice adjustment. Some models use a bleed orifice on the pressure regulator to smooth its opening. When replacing regulators, the bleed orifice must be rein-stalled on the new regulator.

d. The burner is improperly adjusted. Check gas pressure and orifice size or time a gas meter to verify firing rate; check the CO2 to verify the combustion air adjustment.

e. Check the adjustment of the burner gun assembly. Particularly check the pilot position within the gun on Models 200 and 250.

f. Inspect the gun assembly and blast table for warpage or deterioration.

4.2 Flame is not symmetrical as observed through rear

a. Unproportionally high airflow. Check CO2.

b. The gun discs are not perpendicular to the blast tube, or the discs are warped or otherwise out of alignment.

4.3 Nuisance tripping of the flame safeguard.

a. Check gas pressure situation. Marginal pressure during normal times can become low pressure during time of demand and lead to trip-outs, etc. Pressures higher than that for which the gas train is designed can also cause problems. Line pressure should not exceed 13.9' W.C. (1/2 psi) into the standard gas train. Pressures higher than this require an additional stepdown regulator to maintain the pressure below 13.9' W.C. even at "no flow" conditions. A regulator that does not shut off tight at "no flow" will allow a small amount of gas to leak past and eventually the high pressure will build up on the downstream side, thus exceeding the rating of the gas train components.

b. Undersized piping can also cause problems by delivering reducing pressure during times of maximum demand.

c. On modulating burners check the pilot ignition and flame signal when operating at both high fire and low fire.

d. Check that the pilot ignition electrode porcelain bushing is blocking air passage into hole in pilot assembly. Check the pilot burner for cracks that could allow air leakage into the pilot burner. On modulating burners this leakage changes as the burner air damper changes air pressure, and perhaps the pilot will produce a strong microamp signal at low fire but not at high, etc.

e. Observe the flame signal DC volts when turning on the burner switch Any movement of meter needle before the ignition cycle could indicate a short to ground. This could be an intermittent situation from moisture conditions. With pilot gas cock closed any movement during the ignition attempt would indicate ignition interference.

f. Check for loose or cracked pilot gas tubes, air tubes, and fittings that could vary leakage from time to time as vibration might move them around.

g. Check supply voltage and if suspicion warrants arrange to have a recording voltmeter connected to the burner for a period of time.

h. Marginal flame signal. Adjust pilot air and gas and flame rod position.

i. If the pilot air pickup tube is kinked or flattened from bending, pilot air is reduced. When this happens the pilot is unstable and nuisance tripping results. Replace the pilot air pickup tube.

4.4 Modulating burners: Pilotlights, main flame comes on at low fire, but as actuator attempts to reposition for an increased firing rate the flame goes out. Then the sequence is repeated.

a. Check the burner fan air proving switch and tube. As the burner air control damper opens further to provide more air for an increased firing rate, the static pressure inside the fan scroll is reduced. This is the pressure being sensed by the air proving switch, and if it falls below its set point the burner will drop out. The adjustment screw is located next to the wiring box cover. Turn screw CCW to reduce set point.

b. Use a manometer to determine if the gas pressure at the orifice is dropping prior to the flame going out. If gas pressure is dropping, check for a plugged vent on a gas pressure regulator or something that restricts the gas flow in the line so only a low flat rate can occur.

4.5 At the instant spark comes on, the flame safeguard drops out and restarts the pre-purge cycle.

a. Ignition interference. Flame rod or its wire is sensing voltage from ignition. Also determine that ignition electrode spark gap is within specifications.

4.6 When the flame safeguardis powered it locks out and the ALARM LED comes on.

a. Purge card missing or bad, terminals are energized that should not be at that stage, or there is an internal system fault. Replace purge card or RM7895A as indicated.

IM 684-2 21

Typical Parts List - 60 Hz

QTY. MCQUAY PART NO. VENDORVENDOR PART NO.

USED ON MODELS DESCRIPTION

1 0342492-00 Emerson 4526 200—1000 Burner Fan: Motor 1/4 hp, 3450 rpm1 0322486-00 Emerson 457 1100—1500 Motor 1/2 hp, 3450 rpm1 0322484-00 Emerson 458 2000 Motor 3/4 hp, 3450 rpm1 0348611-02 Beckett 22031-07 200—1000 Wheel, 6.25 x 3.438 (.500")1 0342490-05 — — 1100—1500 Wheel, 7.09x 3.16(.625")1 0342490-04 — — 2000 Wheel, 7.50 x 3.16 (.625")1 0330038-00 Antunes SMD4130 200—2000 Air Switch1 0344826-00 Allason 1092 200—2000 Ignition Transformer1 0733008-01 HW RM7895A1014 200—2000 Flame Safeguard (less amplifier & timer)1 0733009-01 HW R7847A1033 200—2000 Amplifier Only (3 seconds)— 0733010-01 HW ST7800A1039 200—2000 Timer Only (30 seconds)— 0733010-02 HW ST7800A1062 200—2000 Timer Only (90 seconds)1 0733007-01 HW Q7800B1003 200—2000 Subbase for Flame Safeguard1 0344884-00 HW V4046C1005 400—2000 Pilot Gas — Solenoid Valve1 0340776-00 Max. RV10 200—2000 Pressure Regulator1 0340773-00 Con. BR 56-111-01 200—2000 Shutoff Cock, .125" l.P. x .25 Tube1 0350196-00 200—2000 Pilot Burner Assembly Complete— 0300032-02 200—2000 Flame Rod— 0413533-00 200—2000 Ignition Electrode Assembly1 0347429-00 200—2000 Ignition Cable1 0365185-00 1100—2000 Ignition Cable1 0347430-00 200—2000 Flame Rod Wire1 0365163-01 200— 000 Pilot Air Pickup Tube1 0365163-02 1100—2000 Pilot Air Pickup Tube1 0348799-01 200 Gun Assembly (less pilot)1 0348799-02 250 Gun Assembly (less pilot)1 0348799-03 320 Gun Assembly (less pilot)1 0348799-04 400 Gun Assembly (less pilot)1 0348800-01 500 Gun Assembly (less pilot)1 0348800-02 640—650 Gun Assembly (less pilot)1 0348800-03 790—800 Gun Assembly (less pilot)1 0348800-04 1000 Gun Assembly (less pilot)1 0357210-01 1100 Gun Assembly (less pilot)1 0357210-02 1400 Gun Assembly (less pilot)1 0357210-03 1500 Gun Assembly (less pilot)1 0357210-04 2000 Gun Assembly (less pilot)1 0373788-02 200—400 Blast Tube Assembly, 4.00 x 20º1 0341017-03 500—650 Blast Tube Assembly, 5.00 x 20º1 0341017-07 790—1000 Blast Tube Assembly, 5.00 x 27 1/2º1 0341017-06 1100—1400 Blast Tube Assembly, 7.00 x 271/2º1 0351647-01 1500—2000 Blast Tube Assembly, 7.00 x 27 1/2º1 0341020-00 200—1000 Blast Tube Gasket, 4-5”1 0341019-00 1100—2000 Blast Tube Gasket, 7"1 0335367-00 200—2000 Switch Off-Auto, 4P2T2 0594688-01 HW B200T1025 200—320 Shutoff Cock, Main 0.752 0594688-02 HW B200T1033 400—500 Shutoff Cock, Main 1.002 0594688-03 HW B200T1041 640—1000 Shutoff Cock, Main 1.252 0594688-04 HW B200T1058 1100—1500 Shutoff Cock, Main 1.502 0594688-05 HW B200T1066 2000 Shutoff Cock, Main 2.001 0340782-00 Max. RV52 200—320 Pressure Regulator, 0.75"1 0340781-00 Max. RV53 400—500 Pressure Regulator, 1.00"1 0340778-01 Max. RV61 640—800 Pressure Regulator, 1.25"1 0340778-04 Max. RV61 1000 Pressure Regulator, 1.25”1 0340778-02 Max. RV81 1100—1500 Pressure Regulator, 1.50"1 0340778-03 Max. RV91 2000 Pressure Regulator, 2.00"1 0733365-02 HW VR43044300 200—320 Combination Gas Control, 0.752 0733878-01 HW V4843A1038 400—500 Main Gas Valve, 1.002 0733878-02 HW V4843A1020 640—1000 Main Gas Valve, 1.252 0733878-03 HW V4843A1012 1100—1500 Main Gas Valve, 1.502 0733878-04 HW V4843A1004 2000 Main Gas Valve, 2.001 0344883-02 Maxon 63-18810 200—320 Modulating Gas Valve, 3/41 0344883-03 Maxon 63-18206 400—500 Modulating Gas Valve, 11 0344883-04 Maxon 63-18207 640—1500 Modulating Gas Valve, 1¼1 0344883-05 Maxon 63-18208 2000 Modulating Gas Valve, 1½1 0479361-01 HW M6161A1004 200—2000 Floating Actuator1 0665348-04 HW M7161A1002 200—2000 Electronic Modulating Actuator1 0665348-03 HW M9161A1012 200—2000 Series 90 Modulating Actuator1 0733371-0l W/R 5A75-10 320—2000 Fan Limit Control1 0733371-02 W/R 5A75-12 200—250 Fan Limit Control1 0342505-00 SUP. DC1209CN 200—2000 Ball Joints for Modulating Linkage1 0234632-00 SUP. CAS-500 200—2000 Crankarm for Modulating Motor1 0342506-00 SUP. CAL-375 200—2000 Crankarm for Air Damper

22 IM 684-2

Tabl

e 5.

(1)

(2)

(2A

)(3

)(4

)(5

)(6

)(7

)(8

)(9

)(1

0)(1

1)(1

2)(1

3)(1

4)(1

5)(1

6)(1

7)(1

8)

BU

RN

ER

M

OD

EL

N

O.

MA

X.

INP

UT

MB

H O

R

CF

H2

MIN

.4

INP

UT

MB

H

OR

C

FH

2

MIN

. C

FM

MA

X.

TR °F

NA

TU

RA

L G

AS

@ 1

000

BT

U/C

U.F

T.M

IN.3

GA

S

INL

ET

P

RE

SS

IN.

W.C

.1

RU

N-

NIN

G

CU

R-

RE

NT

AM

PS

DIM

EN

SIO

NS

GA

S C

ON

N.

SIZ

EP

ILO

TM

AIN

BU

RN

ER

*AIR

P

RE

SS

.TY

P.

IN

W.C

.

O R F **

GA

S

PR

ES

S

AD

J.

IN W

.C.

***A

IR

BO

X

PR

ES

S IN

W

.C.

ST

D

OR

F.

DR

ILL

IN

CH

GA

S M

AN

IFO

LD

OR

IFIC

E

PR

ES

SU

RE

(IN

W.C

.) F

OR

%

OF

MA

X. I

NP

UT

ST

D.

HIG

H

PR

ES

S.

RE

G.

100%

90%

50%

33%

AB

CD

EF

GH

FC

020

250

8323

0080

2.15

583.

402.

10.

272

3.56

2.88

0.89

0.39

6.0

3.3

0.44

0.23

3.32

6.00

6.75

0.38

1.81

0.31

0.75

0.75

FC

025

312

104

3800

612.

0558

3.45

2.4

0.30

23.

37

2.73

0.

84

0.38

6.0

3.4

0.38

0.32

3.

50

6.00

6.

06 0

.47

2.12

0.50

0.

750.

75F

C 0

3240

013

329

5010

01.

8058

2.85

2.7

0.34

43.

54 2

.87

0.89

0.

397.

03.

60.

38

0.63

3.

95

6.00

7.25

0.4

62.

450.

690.

75

0.75

FC

040

500

167

6000

611.

8558

3.30

2.9

0.42

2 3.

75 3

.04

0.94

0.

457.

03.

60.

250.

804.

126.

25

7.25

0.5

22.

40

0.88

1.

001.

00F

C 0

5062

520

846

0010

01.

8558

3.35

2.4

0.42

23.

83 3

.10

0.96

0.35

7.0

3.6

0.25

0.33

4.12

6.50

4.20

0.5

62.

620.

811.

001.

00F

C 0

6480

026

796

0061

1.90

583.

303.

20.

500

3.87

3.1

40.

970.

427.

03.

90.

25

0.55

4.23

6.0

04.

25 0

.42

2.85

2.25

1.

251.

25F

C 0

6581

227

159

7010

01.

6058

3.70

2.6

0.46

93.

88 3

.14

0.97

0.44

7.0

3.9

0.25

0.

564.

275.

305.

65 0

.90

2.95

0.88

1.

251.

25F

C 0

7910

0033

312

000

611.

4058

3.00

2.8

0.56

33.

86 3

.13

0.97

0.42

7.5

3.9

0.35

0.87

4.58

5.

305.

60 0

.80

3.20

1.25

1.25

1.25

FC

080

1000

333

7340

100

1.50

582.

602.

50.

563

3.35

2.7

10.

840.

297.

53.

90.

350.

874.

646.

006.

56 0

.85

3.05

1.25

1.25

1.25

FC

100

1250

417

1500

061

1.60

582.

602.

90.

750

3.67

2.9

70.

920.

239.

04.

20.

121.

004.

906.

88

7.81

0.9

33.

121.

381.

251.

25F

C 1

1013

7549

510

100

100

2.05

583.

322.

80.

703

3.22

2.6

10.

810.

337.

09.

10.

180.

654.

757.

12

7.50

0.8

32.

62—

1.50

1.25

FC

140

1750

583

2100

061

1.95

583.

753.

60.

823

3.58

2.9

00.

900.

348.

010

.00.

121.

075.

177.

507.

250.

68

3.10

—1.

501.

25F

C 1

5018

7578

813

770

100

2.25

583.

703.

70.

813

3.65

2.9

60.

910.

328.

010

.20.

120.

584.

428.

004.

05

0.90

3.76

—1.

501.

25F

C 2

0025

0083

330

000

612.

2558

3.50

4.6

1.00

03.

75 3

.04

0.94

0.22

9.0

10.0

0.12

0.58

4.48

8.00

3.50

1.

074.

32—

2.00

1.25

****

Capacities and Adjustments

No

tes:

1.P

ress

ure

is fo

r m

odul

atin

g bu

rner

s w

ith s

tand

ard

UL

gas

trai

n. F

or O

n-O

ff bu

rner

s, d

educ

t 1 .0

0".

2.G

FH

of n

atur

al g

as @

100

0 B

TU

/cu.

ft.

3.G

as in

let p

ress

ures

ove

r 0.

50 P

SI (

13.9

in. W

.C.,

8 oz

/ sq

. in.

) re

quire

an

addi

tiona

l hig

h pr

essu

re r

egul

ator

.4.

Min

imum

fire

on

mod

ulat

ing

burn

er.

5.G

SA

bur

ner

= 6

.00

inch

es

Key

:➀

Pilo

t gas

pre

ssur

e ad

just

men

t➁

Pilo

t pre

ssur

e ga

uge

tap

(1/4

" fla

re m

ale)

➂ M

ain

gas

pres

sure

adj

ustm

ent

➃ B

urne

r ai

r ad

just

men

t➄

Bur

ner

air

pres

sure

por

t➅

Mai

n ga

s or

ifice

(in

side

uni

on)

➆ P

ilot g

as o

rific

e (in

side

test

tee)

➇ P

ilot g

as te

st te

e➈

Mai

n m

anifo

ld p

ress

ure

tap

*Rea

din

g is

with

air

da

mp

er

at

low

fir

e p

osi

tion

on

mo

du

latin

g b

urn

ers

, co

ld h

ea

t e

xch

an

ge

r.**

Pilo

t g

as

ori

fice

dri

ll n

um

ber

size

.**

*Re

adin

g a

t h

igh

fir

e. N

ot

ap

plic

ab

le o

n C

ana

dia

n b

urn

ers

.**

**E

xce

pt

3 p

si a

nd le

ss =

1.5

0"

Fig

ure

16a.

Fig

ure

16b.

Fig

ure

16c. V

alve

s, D

amp

ers

& O

per

ato

rs s

ho

wn

in L

ow

Fir

e P

osi

tio

n

4

96

F

GH

IGH

FIR

E

LOW

FIR

E

B

5

3

17

82

E

E

CD

H

IM 684-2 23

Fir

ing

R

ate

Des

crip

tio

n o

f R

ead

ing

Dat

e o

f R

ead

ing

s

1

Max

. Rat

e S

cale

= 1

00

Gas

Man

ifold

Pre

ssur

e (I

n. W

.C.)

*2

Gas

Life

Pre

ssur

e (I

n. W

.C.)

*3

Fla

me

Sig

nal (

DC

Vol

ts)

4A

mbi

ent T

empe

ratu

re (

Deg

. F)

5F

lue

Gas

Tem

pera

ture

(D

eg. F

)6

Flu

e G

as C

0 2 (p

erce

nt)

7F

lue

Gas

CO

(P

PM

)8

Air

Pre

ssur

e in

Box

(In

. W.C

.)9

Bur

ner

Mot

or V

olts

10B

urne

r M

otor

Am

ps

11

Mid

. Rat

e S

cale

= 5

0

Gas

Man

ifold

Pre

ssur

e (I

n. W

.C.)

*12

Gas

Lin

e P

ress

ure

(In.

W.C

.)*

13F

lam

e S

igna

l (D

C V

olts

)14

Am

bien

t Tem

pera

ture

(D

eg. F

)15

Flu

e G

as T

empe

ratu

re (

Deg

. F)

16F

lue

Gas

C0 2