service bulletin booklet - bosch climate · on how to clean pilot assembly and orif ice. 3. if...

Service Bulletin BookletFor Compact model water heaters

GWH 260 PN, GWH 425 PN, GWH 425 HN

GWH 1000 P, GWH 1600 P, GWH 1600 H

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CT-02page 1 of 1

rev 10/06

Bosch Water Heating340 Mad River Park, Waitsfield, VT 05673

©BBT NORTH AMERICA CORPORATIONBosch Group

THERMOCOUPLE AND PILOT TESTMODELS: 1000P, 1600P,

260PN, 425PN

A. Pilot does not stay lit when the button isreleased.

1. When lighting pilot, ensure the gas valve button is fully de-pressed and held down for at least 15 seconds after pilot islit.

2. Pilot flame should be a sharp blue flame that fully engulfsthe thermocouple tip. If pilot does not look this way, pleasesee bulletin ‘CT-22 Cleaning pilot assembly’ for instructionson how to clean pilot assembly and orifice.

3. If heater is equipped with an AQ4 power vent kit (models1600P and 425PN only), press reset button on power ventspill switch to check if it is tripped. NOTE: running the heaterwithout electrical power to power vent fan will trip the spillswitch. Also check the AQ4 safety circuit connections forcorrosion or loose connections. Consult AQ4 manual for partlocations.

4. Check the electromagnet connections. The electromagnetis located on the back side of the gas valve. The electromag-net connection from the thermocouple is a 5 mm brass nutthat screws into a 17 mm aluminum nut. Tighten both nutssnugly but do not over tighten.

5. Check if connections at both temperature limiters (ECO) areloose or corroded. Clean any corrosion with very fine sandpaper or an eraser and reconnect leads.

6. If cleaning the terminals attached to the ECO’s does not fixthe problem, choose one ECO and remove two wires at-tached. Connect a jumper wire between the two wires re-moved from the ECO. Try to relight the pilot. If the pilotflame now remains on, the ECO may be defective. If thepilot still goes out, remove jumper, reconnect wires leadsand perform the same step with the other ECO.

Note: Never attempt to operate heater for normaluse with jumper wire connected!

7. Replace ECO.8. Have a licensed gas technician verify the proper operation of

the thermocouple. To test the thermocouple, disconnect wirefrom the thermocouple where it connects to the upper ECO(located top right side of the heat exchanger). Insert a multi-meter probe into the thermocouple lead and attach or holdthe other probe to the metal chassis of the heater (DC com-mon). Light the pilot flame and hold button while observingthe meter reading. If the reading is 24mVDC or more thethermocouple is good.

B. Pilot goes out during use

1. Light the pilot and allow it to warm the thermocouple tip for2 minutes.

2. Perform drop test by blowing out the pilot flame and listenfor the electromagnet to close. This closure will make a dis-tinct clunk noise as it shuts. The time between blowing outthe flame and the electromagnet closing should be between20 and 30 seconds. Units equipped with an AQ4 power ventkit have drop times between 10 and 15 seconds.

3. Repeat drop test several times to confirm it is consistent4. If drop times are not within specifications, then follow steps

2-7 in section A. After each step, repeat drop test. Proceedto the next step until drop test is within specifications.

C. Pilot goes out during use and drop test iswithin specifications.

1. Check the vent size and length. Vent should be 5 inches indiameter for the 1600P and 425PN and 4 inches in diameterfor the 1000P and 260PN. The heater must have a rise of 1-foot before any elbows in the vent system, at least 6 feetvertical in length and terminate through the roof. Any reduc-tion in vent size or the presence of an elbow directly on thetop of the unit may cause the flue gas sensor to trip the pilotsafety circuit. Please see the venting section in the manualfor more detailed information regarding the required ventingfor this heater.

2. Inspect the draft hood and heat exchanger fins for signs ofsoot build-up or any other foreign material such as spiderwebs. Clean out any debris found in the vent hood. Signs ofsoot indicate insufficient combustion air or exhaust draft.Check for vent assembly blockage or combustion air block-age on the underside of the unit. Ensure combustion airrequirements are being met as specif ied in the installationmanual.

3. Measure the outgoing temperature of the hot water exitingthe unit. Temperature in excess of 160F may trip the pilotsafety circuit. The heater must not be supplied with water inexcess of 90F. Preheated water may cause the heater tooverheat the outlet water and shut down as a safety precau-tion.

Before replacing the thermocouple, please test thethermocouple safety circuit and the pilot as follows.


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rev 09/06



CHECKING THE DRAFTMODELS: 1000P, 1600P, 1600H

260PN, 425PN, 425HN

1. Close all doors and window in the building.2. Operate all fuel burning appliances and exhaust

systems in the building with the exception of thetankless water heater. Allow time for these items toutilize the air in the structure. Up to one hour maybe necessary.

3. Remove the cover from the tankless unit and hold arecently extinguished match, candle, or any othervisible smoke source in front of the triangular open-ing on the draft diverter.

4. The smoke should be sucked quickly into the openingand up the exhaust vent. If the smoke is blown back,a negative air situation exists and must be corrected.See the combustion air section in the manual orbulletin CT-05 Negative air and freeze prevention.

5. Now run the heater for 10 minutes, then hold asmoke source at the top right side of the draftdiverter. The smoke should be drawn in the louverson the side. If this is not the case, the unit is notdrafting properly and flue gases are being exhaustedinto the space in which the heater is installed. Thisis not safe and must be corrected. Reference theventing section in the manual to ensure venting is inaccordance with the manufacturer’s specifications.

Note: Poor venting can result in exces-sive sooting around the water heater,overheating, and release dangerouscarbon monoxide into the living spacecausing serious injury and/or death.

Note: Damage to the heater as a resultof improper venting will not be coveredunder warranty.

Step 3: Hold extiguishedmatch here


1000P. 1600P, 1600H,260PN, 425PN, 425HN


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rev 10/06



CHECKING GAS PRESSUREMODELS: 1000P, 1600P, 1600H

260PN, 425PN, 425HN

A. Connecting manometer:

1. Turn off gas using installer supplied manual shutoff.2. Remove front cover (see manual for instructions) and lo-

cate inlet gas pressure tap above the regulator on the gasinlet pipe and the manifold gas pressure tap on the rightside directly below the burner (Fig. 1).

3. Select appropriate pressure tap per specific pressure test(see steps B and C). Loosen the screw from test point fit-ting (do not remove) and connect manometer tube on testpoint.

B. Static pressure test (Inlet pressure taponly)

1. Turn gas supply back on.2. Operate all other gas appliances at maximum output.3. Record static pressure reading in Table 1.4. Leave manometer connected to inlet tap for operating pres-

sure test.

C. Operating pressure test

1. Light pilot if neccessary (1000P, 1600P, 260PN and 425PNmodels).

2. All other gas appliances should still be running at full ca-pacity.

3. Set heater to maximum output:1000P, 1600P, 260PN, 425PN:

Set gas slide control to the right. Turn temperatureadjustment knob full clockwise.

1600H, 425HN:Turn power adjustment knob full clockwise. Turntemperature adjustment knob full clockwise.

4. Open all hot water taps supplied by this unit.5. Record inlet tap operating pressure reading in Table 1.6. Turn off gas supply as well as all hot water taps. Disconnect

manometer from the inlet tap. Tighten screw in tap fittingor gas leak may occur.

7. Reconnect manometer to the manifold gas pressure tap.8. Turn gas supply back on and follow steps 1 through 4.9. Record manifold tap operating pressure reading in Table 1.10. Turn off gas supply as well as all hot water taps. Disconnect

manometer from the manifold tap. Tighten screw in tap fit-ting or gas leak may occur.

11. Put cover back on water heater, open gas supply and returnheater to service.

TABLE 1

Static gas pressure: “ W.C.

Required static gas pressure (all models:NG 7” - 14” W.C.LPG 11” - 14” W.C.

Operating gas pressure:

Inlet Tap “ W.C.

Manifold tap “ W.C.

Minimum require operating gas pressure:

GAS PRESSURE TEST POINTS

Mainfold tap

Inlet tap

FIGURE 1


CT-05page 1 of 1

rev 10/06



NEGATIVE AIR & FREEZEPREVENTIONMODELS: 1000P, 1600P, 1600H,

260PN, 425PN, 425HN

Negative Air• Negative air pressure in a structure occurs when air con-

sumed by fuel burning appliances or exhaust systems in thatstructure exceeds the amount of air available.

• Here is a list of items that consume air within a typical house-hold:• Stove exhaust fans• Furnaces• Water heaters• Fireplaces/ Woodstoves• Bath fans• Dryers

• All of these items must be taken into account when makingprovisions for a proper amount of fresh air from the outside.

• If the building is new construction, air infiltration from theoutside will be limited and provisions for extra air supplyshould be made. If the building is older construction, air mayinfiltrate into the house through unplanned sources such aswindow frames, door jams, sill plates or idle chimney flues.These sources still may not be providing the adequate amountof air and additional sources of fresh air should be consid-ered.

Why Negative Air is BadCold air from the outside is drawn through the water heater’sflue pipe because other fuel burning appliances or exhaustsystems in the structure require more air than the dwellingcan supply. When the required amount of air for the fuelburning appliances or exhaust systems in the structure isnot being supplied to them, they find the flue pipe on thewater heater an acceptable means of supplying themselves.Thus, freezing cold air is pulled down the water heater’s flue,drawn over the copper heat exchanger, potentially freezingit and the water valve below. Because, when idle, the waterheater holds only cold water, freezing can happen quicklypossibly causing leaks or ruptures in the heat exchanger and/or the water valve. The water heater does not pull air throughits flue pipe – if you were to remove the heater, the air wouldcontinue to come down your f lue pipe. You must have the airbalanced in the structure to correct this problem. Consulta-tion with a heating, ventilating and air conditioning (HVAC)specialist is recommended.

Note: Poor venting can result in excessivesooting around the water heater, overheat-ing, and release dangerous carbon mon-oxide into the living space causing seri-ous injury and/or death.

Note: Damage to the heater as a result ofimproper venting will not be covered un-der warranty.

Checking for Negative Air1. Close all doors and windows in the building.2. Operate all fuel burning appliances and exhaust systems in

the building at full capacity with the exception of the tanklesswater heater. Allow time for these items to utilize the air inthe structure. Up to one hour may be necessary.

3. Remove the cover from the tankless unit and hold a recentlyextinguished match, candle, or any other visible smoke sourcein front of the triangular opening on the draft diverter.

4. The smoke should be sucked quickly into the opening and upthe exhaust vent. If the smoke is blown back, a negative airsituation exists and must be corrected. See the combustionair section in the manual for specifications.

5. Now run the heater for 10 minutes, then hold a smoke sourceat the top right side of the draft diverter. The smoke shouldbe drawn in the louvers on the side. If this is not the case,the unit is not drafting properly and flue gases are beingexhausted into the space in which the heater is installed.This is not safe and must be corrected. Reference the vent-ing section in the manual to ensure venting is in accordancewith the manufacturer’s specif ications.



DRAFT DIVERTER FOR:1000P, 1600P, 1600H,260PN, 425PN, 425HN


CT-06page 1 of 1

rev 10/06



OVERCOMING FLUCTUATINGTEMPERATURESMODELS: 1000P, 1600P, 1600H

260PN, 425PN, 425HN

Introduction

Temperature fluctuations from hot to cold during use is typi-cally caused by a back pressure on the water flowing throughthe tankless water heater. This decreases the flow rate throughthe tankless water heater below the required activation flowrate and shuts the heater down. Follow these instructions stepby step to overcome this phenomenon.

Clean faucet aerators and shower heads

Check for restrictions in outlets, which would limit hot waterdemand and may assist in deactivation scenario. For sinks,remove faucet aerator on end of sink. Flush and clean screenand reinstall. For showers, remove showerhead and f lush. Ifplugged with mineral deposits, clean according tomanufacturer’s suggestions or replace. (Note: if showerhead iswand style/hand held, corrugated tube connecting to head maybe too restr ictive. Enlarging tube or using a normal showerheadmay be the solution.)

Clean Inlet filter screen

Inlet filter screen is located in bottom of the water valve nearthe cold water connection side (right) at the rear of the unit.Please see bulletin CT-12 Cleaning inlet f ilter for more detailedinstructions.

Check for plumbing crossover

A plumbing crossover can be caused by a failed cartridge at asingle lever faucet, incorrect plumbing or a faulty mixing valvein the piping. The crossover will create a back pressure on thewater heater and prevent an adequate flow of water through it.Close installer supplied cold water shut off valve to the heater(if none installed, install before proceeding). Open all hot wa-ter taps supplied by the heater. Wait 5 minutes and check alltaps. Water running is a sign of a plumbing cross-over. Consulta local plumber or service person for help in correcting a plumb-ing crossover.

Confirm water pressure

Water pressure should stay above 30psi during operation. If ona well system, we recommend a pressure setting of 40-60psi.

Lower temperature

The temperature can be lowered by moving gas slide control tothe left. On models 1600H and 425HN, turn power adjustmentknob clockwise. See bulletin CT-07 Lowering temperatures foralternative methods of lowering output temperature.

Confirm activation rate of the heater

1. Turn flow control knob on the front of heater fully clockwise.2. Fully open one hot water tap.3. Return to heater and shut cold water supply valve.4. Slowly open cold water supply valve until the burners ignite.5. Return to hot water tap and measure f low rate by timing

how long takes to fill a quart container. A fill time of 30seconds indicates a proper activation rate of 0.5 gallons perminute (GPM)*. See Table 1 for other flow rate conversions.

6. Repeat steps 4 and 5 a few times to check the accuracy oftest.

* A fill time less than 30 seconds indicates an activation rateabove the required 0.5GPM and a possible problem withinthe heater’s water valve. Periodic maintenance is requiredon this water valve. Visit our website for parts and servicebulletins for this procedure.

GPM Quar t Jar(in Seconds)

Gallon Jug(in Seconds)

.50 30 120

.75 20 80

1.00 15 60

1.25 12 48

1.50 10 40

1.75 8.5 34

2.00 7.5 30

2.50 6 24

3.00 5 20

3.50 4.25 17

4.00 3.75 15

TABLE 1


CT-07page 1 of 1

rev 10/06



LOWERING TEMPERATUREMODELS: 1000P, 1600P, 1600H

260PN, 425PN, 425HN

When the temperature adjustment knob on the front ofheater is turned all the way clockwise (hotter temps.),the heater requires a 0.6 gallon per minute flow rate toactivate. When the temperature adjustment knob is turnedall the way counter-clockwise (cooler temps.), the unitwill require a 1.1 gallon per minute flow rate to activate.Although common sense tells us to turn this knob counter-clockwise to achieve a lower outlet temperature, we rec-ommend that the temperature adjustment knob be keptall the way clockwise, to take advantage of the 0.6 gpmactivation point. Please move knob to this setting andfollow the steps below for alternative ways of loweringtemperature.

Solution:Increased water flow helps to lower the outlet tempera-ture and ensures that the heater stays activated espe-cially when mixing cold water at the outlet.1. Increase the flow by cleaning the inlet filter screen in

the heater. (Fig. 1) Consult bulletin CT-12 Cleaning in-let filter for more detailed instructions on removingthe inlet filter.

2. Increase the flow at all outlets. For sinks, remove fau-cet aerator screen on end of sink. Flush screen withwater to clean and reinstall. For showers, removeshowerhead and flush with water. If the head is cloggedwith mineral deposits, clean according tomanufacturer’s specifications or replace. Please note,if the showerhead is a hand-held/wand style, these canbe extremely restrictive. If cleaning or flushingshowerheads/aerators fails to produce adequate flow,try upgrading with higher flowing versions.

3. Decrease the gas volume by moving gas slide control(models 260PN, 425PN, 1000P, 1600P) or gas controlknob(models 425HN, 1600H) to the small f lameposition.

4. If temperatures are still too hot, increase water flowby removing the water governor/restrictor. Shut off coldwater supply to heater and remove wire clip on volu-metric water governor housing from right side of wa-ter valve behind water outlet pipe. (Fig. 2) Removeretaining cap with o-ring and spring/cylinder assem-bly inside. (Fig. 3) Re-install retaining cap with lubri-cated o-ring and wire clip only. No inner componentsshould be left inside. Operate heater with the flowcontrol turned all the way clockwise.

FIGURE 1

Removing Water Filter

FIGURE 3

Water Governor Location

Cylinder

FIGURE 2

Water Governor Location

Water governorclip

Spring

Retainingcap


CT-08page 1 of 1

rev 10/06



DESCALINGMODELS: 1000P, 1600P, 1600H

260PN, 425PN, 425HN

Instructions for removing scale from heatexchanger.

1. Disconnect electrical supply from the water heater.2. Shut off the water supply to the water heater using

(installer supplied) isolation valve.3. Open hot water taps to drain and relieve pressure

from the plumbing system.4. Drain water from the unit’s heat exchanger by

disconnecting inlet and outlet water connections.5. Connect the line (A) from the outlet of the circulat-

ing pump (installer supplied) to the inlet waterfitting on the water heater.

6. Using another line (B), connect to the water outletfitting on the water heater. Route the other end ofthis line into a descaling reservoir.

7. Using a 3rd line (C) from the descaling reservoir,connect to the inlet side of circulating pump. Verifythere is a filter on the end of the line in thedescaling reservoir.

8. Make sure all connections are “hand tight.”9. Fill tank with descaling solution so lines inside are

submersed. We recommend a straight white vinegarsolution. If using a commercial descalant, refer tomanufacturer’s instructions on dilution with water.

11. Operate the circulating pump.12. Make sure there are no leaks and the solution is

flowing from the descaling reservoir through theheat exchanger and returning to the reservoir.

13. Run solution through the heat exchanger until thesolution returning to the descaling reservoir comesout clear. (Changing to a fresh solution may benecessary during this process)

14. Disconnect all lines and drain all solution from heatexchanger. Properly discard solution.

15. Position a container below the hot water outlet andreconnect cold water supply. Open cold watersupply isolation valve and flush heat exchanger withclean water.

16. Shut cold water isolation valve and reconnect hotwater supply to the water heater.

17. Reconnect electrical supply to unit, open waterisolation valves, and return the unit to service.

PUMPA

C

B

RESERVOIR


CT-11page 1 of 1

rev 10/06



WINTERIZING FOR SEASONAL USEMODELS: 1000P, 1600P, 1600H

260PN, 425PN, 425HN

Please note that the instructions in the manual state that the water heater must not be installed in a location whereit may be exposed to freezing temperatures. If the heater must be left in a space which is likely to experience freezingtemperatures (less then 32º F), all water must be drained from the heater. Damage as a result of improper drainagewill not be covered under warranty.

Draining the heater

1. Shut off gas to heater.2. Shut off water supply to the heater using installer sup-

plied cold water isolation valve. If none installed, in-stall before proceeding.

3. Open lowest hot water faucet to drain lines and re-lieve pressure in heater.

4. Position a bucket below water connections to waterheater.

5. Remove the retaining clip (Fig. 1, Num. 1) from thethreaded bushing.

6. Remove the threaded bushing (Fig. 1, Num. 2) fromthe water valve.

7. Contents of heater and water lines will drain.8. Removal of piping between the water valve and heat

exchanger may be necessary to ensure all water hasbeen drained (Fig. 1, Num. 3)On Models 1000P, 1600P, 260PN, 425PN:Remove retaining clips at water valve and heat ex-changer connections.On Models 1600H, 425HN:Remove reatining clips at water valve and base ofhydrogenerator.

9. Remove piping and save for reinstallation when heateris returned to service.

Note: If using the AQ4 powervent, all f lowswitch piping should be disconnected anddrained.

FIGURE 1


CT-12page 1 of 1

rev 10/06



CLEANING INLET FILTERMODELS: 1000P, 1600P, 1600H,

260PN, 425PN, 425HN

Removing water filter

1. Shut off the installer supplied cold water isolationvalve to the heater. If one is not installed, installbefore proceeding.

2. Open the nearest hot water tap to drain the plumb-ing lines.

3. Position a bucket under the heater’s water valveassembly to catch any water that may drain from theheater.

4. Remove the retaining clip located at base of watervalve (Fig. 1, Num. 1).

5. Remove the threaded bushing (Fig. 1, Num. 2) toaccess the cylindrical filter inside.

6. Remove filter, clean with water and inspect fordamage.

7. If the filter is at all damaged, it should be replaced.

FIGURE 1


CT-13page 1 of 2

rev 10/06



REMOVING AND CLEANINGBURNERSMODELS: 1000P, 1600P, 1600H,

260PN, 425PN, 425HN

A. Removing pilot assemblyModel 1000P, 1600P, 260PN, 425PN (Fig 1):1. Shut off gas and water to heater, then remove front

cover.2. Remove wire clip holding top of pilot tube into

bracket.3. Move lower end of pilot tube to left to release from

black clip on gas valve. Be sure to catch air screenattached to base of pilot tube.

4. Pull upwards on upper end of pilot tube to releasefrom bracket.

5. Remove black clip from bracket to release spark elec-trode.

6. Gently press down on top of thermocouple to releaseit from bracket.

FIGURE 3

FIGURE 4Model 1600H, 425HN (Fig. 2):1. Shut off gas and water to heater, then remove front

cover.2. Remove both pilot bracket screws and pilot shield from

front of burners.3. Remove pilot assembly from burner bracket. Be sure

to catch air screen secured to base of pilot assembly.

B. Removing burners1. Remove 2 burner set screws on the right side of the

gas valve. (Fig. 2)2. Remove four screws from both right and left burner

brackets and set aside. (Fig. 3)3. Push entire burner assembly up to seperate from the

gas valve.4. Tilt right side of burners up and slide them out at an

angle to the left. (Fig. 3)

Burner bracket location(425PN model shown)

FIGURE 2

Pilot shieldPilot bracketscrewsBurners

Pilot airscreen

1600H, 425HN pilot assembly

1000P, 1600P, 260PN, 425PN pilot assembly

FIGURE 1

Pilot air screen

Pilot wire clip

Burners

Pilot tube

Thermocouplelead

Pilot airscreen

Burner setscrews

CT-13page 2 of 2rev 10/06



C. Cleaning burners1. Use a soft wire brush across burner fins to loosen any

debris and then vacuum out.2. Check to see that the 18 brass gas injectors in the

rear of the burner assembly are clean. To access,remove 8 Philips head screws to the left and right ofthe two center brass Philips head screws at the rearof the burner. The burners should separate into twohalves exposing injectors. Blow clean with com-pressed air or carburetor cleaner and wipe dry withcloth. Do NOT poke injectors or attempt to clean withdrill bits, wires or other objects. Clean rear venturipassages with a pipe cleaner and soapy water. Rinseclean and let dry before reinstalling. Follow instruc-tions in reverse to reconnect burner halves.

D. Reinstalling burners1. Reinstall burners into burner area.2. Reinstall set screws on right side of gas valve and

tighten.3. Reinstall right and left burner brackets with the four

screws. The brass screws attach to frame.

E. Reinstalling pilot assembly and tubeModels 1000P, 1600P, 260PN, 425PN:1. Reinsert thermocouple and snap into place. Thermo-

couple tip should sit 1/4” above the burner bed.2. Put spark electrode into place and attach with clip.

3. Slide upper end of pilot tube into bracket on burnerassembly and reinsert pin.

4. Slide base of pilot tube to the right into clip. Ensurepilot air screen is installed between pilot tube and pi-lot orifice.

Models 1600H, 425HN:1. Slide pilot air screen over pilot tube.2. Slide pilot assembly into place. Reinsert pilot shield

and secure with screws to the burner assembly.

F. Returning heater to serviceModels 1000P, 1600P, 260PN, 425PN:1. Turn on gas and light pilot. Test for possible gas leaks

where burners connect to the gas valve.

Models 1600H, 425HN:1. Turn on gas and check for leaks where the burners con-

nect to gas valve by applying leak detecting solution asyou initiate water flow to activate the heater. Allowenough time to bleed all air in gas line. Bubbles are asign of a leak.

All models:2. If there are bubbles at either connection immediately

shut off water and gas. Loosen the burner set screwson the right side of gas valve. Remove the burners andinspect the o-ring. Replace if damaged. Reseat burnersand tighten set screws. Check again for leaks.

3. Replace front cover when complete.

REMOVING AND CLEANINGBURNERS

FIGURE 5

Burners disassembled

Burner fins

Burner venturi passage

Gas injectors


CT-14page 1 of 1

rev 10/06



UNLOCKING THE REGULATORMODELS: 1000P, 1600P, 1600H,

260PN, 425PN, 425HN

If the Maxitrol regulator supplied with your water heateris fed gas or air at too high a pressure, it will cause it to“lock up” and stop delivering gas to heater. This is themethod for “unlocking” the maxitrol regulator.

NNNNNooooottttte: e: e: e: e: This procedure should only be performedby a licensed gas technician

1. Shut off main gas supply to heater.2. Locate Maxitrol regulator at bottom of water heater.3. Confirm that the arrow on the back of the regulator is

pointing up towards the heater and in the same direc-tion of gas flow. If not, the regulator is installed up-side down. Reinstall so that the arrow indicates theproper direction of gas flow.

4. Unscrew slotted cap. (Fig.1)5. The inner plug needs to be returned to the same spot

after unlocking so count threads or measure to facili-tate this.

6. Turn inner plug counter-clockwise to remove.7. Remove spring (do not lose).8. Use the eraser on end of pencil to push in on the dia-

phragm to return to unlocked position.9. Install spring first, then install plug and turn clock-

wise to return to measured position.10. Reinstall slotted cap.11. Return heater to service after correcting over pres-

sure situation.

FIGURE 1

slotted capgas flow





REPLACING HEAT EXCHANGERMODELS: 1000P, 1600P, 1600H,

260PN, 425PN, 425HN

Removing heat exchanger

1. Remove cover as per installation manual2. Turn off gas to heater using installer supplied shutoff

valve.3. Close installer supplied cold water shutoff valve to

heater (if none installed, install before proceeding.)4. Open lowest hot water faucet to drain lines and relieve

pressure in heater.5. Position a bucket below water connections to water

heater.6. Remove the retaining clip (Fig. 1 Num. 1) from the

threaded bushing. Then remove the threaded bushing(Fig. 1 Num. 2) from the water valve.

7. Contents of heater and water lines will drain to bucketbelow.

8. Once all water has drained, reinsert threaded bushinginto water valve and secure with retaining clip

9. Locate and remove clips on both left and right sideconnections on lower rear of heat exchanger. (Fig. 2,Num. 1)

10. Loosen Phillips head screw on temperature limiter(ECO) and remove from heat exchanger mount. (Fig.2,Num. 2)

11. Remove covering angle strip which runs horizontallyat top of heat exchanger. (Fig. 2, Num. 3)

12. Remove heat exchanger from heater by pulling top ofheat exchanger forward. When the back edge of theheat exchanger clears the draft diverter, pull heat ex-changer up and out.

Installing heat exchanger

1. Install new heat exchanger in heater.2. Mount covering angle strip across the top of heat ex-

changer. (Fig. 2, pos. 3)3. Reconnect water pipes to heat exchanger and rein-

stall retaining clips. NOTE: Lubricate o-rings on pipesbefore connecting. (Fig. 2, pos. 1)

4. Remount temperature limiter (ECO) on upper right ofheat exchanger. (Fig. 2, pos. 2)

5. Turn water on and check for leaks at connections.6. Open gas supply, replace cover and return heater to

service.

FIGURE 1

FIGURE 2





CLEANING AND REPLACING PILOTASSEMBLYMODELS: 1000P, 1600P, 1600H

260PN, 425PN, 425HN

For 1000P, 1600P, 260PN, 425PN models:

Removing pilot tube and orifice1. Shut off gas to heater and remove cover per installation

manual.2. Remove wire clip holding upper end of pilot tube into

burner bracket. (Fig. 1)3. Remove lower end of pilot tube from black clip on gas

valve being careful not to damage cylindrical air screen4. Lift up pilot tube and remove from bracket

Cleaning pilot tube and orifice1. Blow out pilot tube and air screen.2. Remove brass hex-headed pilot orifice from gas valve

with 8mm wrench. Black clip may have to be removedwith pliers to access orifice with socket wrench

3. Clean orifice with compressed air or aerosol carburetorcleaner. (NOTE: Do not ream or poke any object throughorifice opening).

Reinstalling pilot tube and orifice1. Screw clean or new orifice into gas valve and tighten

with 8mm wrench. Do not over tighten.2. Place cylindrical air screen over pilot orifice. Angle top

of air screen outwards.3. Feed bottom of pilot tube into angled cylindrical air

screen. Push bottom of pilot tube with air screen intoblack clip until it snaps into place. NOTE: Air screenmay become deformed during this process. Simply moldback into cylindrical shape by hand.

4. Replace cover, open gas supply and return heater toservice.

6. If pilot flame is not strong and blue, replace orifice (NGis stamped 4C, LP is stamped 3C).

For 1600H, 425HN models:

Removing pilot assembly and orifice:1. Shut off gas to heater and remove cover per installation

manual.2. Remove 2 philips head screws holding pilot shield and

pilot assembly to front of burner. Remove pilot shield.3. Remove pilot assembly from burners (with spark elec-

trode and flame sensor) being careful not to damagecylindrical air screen on bottom.

Cleaning pilot tube and orifice1. Blow out pilot tube and air screen.2. Remove brass hex-headed pilot orifice from top of pilot

electrovalve with 8mm wrench.3. Clean orifice with compressed air or aerosol carburetor

cleaner. (NOTE: Do not ream or poke any object throughorifice opening).

Reinstalling pilot assembly and orifice:1. Screw clean or new orifice into pilot electrovalve and

tighten with 8mm wrench. Do not over tighten.2. Insert pilot assembly into burner and fit cylindrical air

screen onto orifice and pilot tube.3. Insert screws through pilot shield and pilot assembly

into burner and tighten.5. Replace cover, open gas supply and return heater to

service.6. If pilot flame is not strong and blue, replace orifice (NG

is stamped 2C, LP is stamped 1C).

FIGURE 2

Pilot shield

Pilot bracketscrews

BurnersPilot airscreen

1600H, 425HN pilot assembly1000P, 1600P, 260PN, 425PN pilot assembly

FIGURE 1

Pilot air screen

Pilot wire clip

Burners

Pilot tube

Thermocouplelead

Pilot orificePilot orifice


CT-23page 1 of 2

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WATER VALVE REBUILDMODELS: 1000P, 1600P, 1600H

260PN, 425PN, 425HN

A. Preparation

Tools needed:Philips screwdriverFlat screwdriverNeedle-nosed pliersContainer to catch water

1. Shut off gas and water supply to heater.2. Open faucet to relieve pressure.3. Pull off temperature adjustment knob (all models)

and gas control knob(1600H, 425HN only).4. Unscrew cover screws and remove cover.5. Unscrew cold water supply pipe from rear of water

valve and catch remaining water.6. Disconnect water pipe to heat exchanger by remov-

ing retaining clip and gently pulling pipe to the right.

B. Removing water valve

1. Support water valve with one hand while releasingwater valve from gas valve by loosening 2 set screwsfrom underneath. (Fig. 1) Do not loosen 3 largerscrews holding plate onto bottom of gas valve or 1screw holding on microswitch. Remove water valvefrom heater.

••••• If set screws do not unscrew easily do not forcethem as the gas valve may be damaged. Try adescaling solution (white vinegar, CLR® or otherdescaling solution) on screw threads. Let sit for 1hour, try again to remove set screw(s) without forc-ing.

••••• If still unable to remove, call 800-642-3111 for help.

C. Removing old parts

1. Remove the 5 cover screws from metal retaining plateand separate 2 halves of water valve. (Fig. 2)

2. Remove and inspect diaphragm from water valve,clean if necessary, replace if damaged or warped byexcessive heat. (Fig. 3, pos. 2)

3. Remove pushrod assembly by holding water valvecover and pressing pushrod sleeve firmly against ahard surface. (Fig. 3, pos. 10)

4. Remove retaining clip and threaded bushing to accessinlet water filter. Remove and clean or replace filter.(Fig. 3, pos. 6)

5. Remove retaining clip (Fig. 3, pos. 7) and volumetricflow governor. (Fig. 3, pos. 8)

6. Remove venturi from outlet port to heat exchanger.Grasp with needle-nosed pliers and twist whilepulling. (Fig. 3, pos. 9) Ensure that venturi passagesare clean as well as passage in water valve body.

7. If the venturi or water valve body has evidence ofmineral build-up, soak in straight white vinegar for ½hour. Brush parts clean and flush with water.

Water valve set screw location

FIGURE 1

2 Setscrews

Water Valve

FIGURE 2

Coverscrews(5)

Pushrodsleeve

Threadedbushing(Waterfilter)

Metalretainingplate

CT-23page 2 of 2

rev 10/06



D. Rebuilding water valve

1. Place diaphragm in right side of water valve, ensuringthat ring on outer edge is in recess.

2. Liberally lubricate both ends of new pushrod andinstall pushrod assembly into water valve cover,pressing firmly in place with thumbs. (Fig. 3 pos. 10)

3. Reassemble 2 halves of water valve with metal retain-ing plate. Install and tighten 5 cover screws (Fig. 2).

4. Install volumetric flow governor with plug and retain-ing clip. Lubricate O-ring on plug before reinserting.

5. Lubricate O-rings on venturi and install.6. Install inlet water filter and threaded bushing with

retaining clip.

E. Installing water valve

1. Remove, lubricate and reinstall water valve setscrews in gas valve. Do not thread screws in fully. 1to 2 revolutions maximum (Fig. 1).

2. Firmly seat water valve into right side of gas valvewith temperature adjustment shaft facing outward(Fig. 3, pos 11).

3. Now tighten set screws fully and evenly.4. Lubricate O-ring on pipe to heat exchanger, put into

water valve and secure with retaining clip from top.5. Reconnect cold water inlet flex pipe with washer.

FIGURE 3

F. Testing operation

Important: Before firing the heater, run water throughheater to check for leaks and purge air.

1. Replace and tighten cover and reinstall knob(s).2. 1000P, 1600P, 260PN, 425PN models: light pilot and

slide control to the right to large flame position.3. Shut off water at heater inlet and open hot water

faucet.4. Turn temperature adjustment knob to full clockwise

position.5. Slowly open inlet water supply just until burners

ignite and no further.6. Measure water flow at open faucet to verify proper

activation rate of 0.6 gallon per minute (quart in 25seconds or gallon in 100 seconds).

7. Shut water off at heater and observe burners toverify that they go out immediately when water f lowstops.

WATER VALVE REBUILD

1. Water valve cover screws (5)2. Water valve diaphram3. Push rod4. Push rod sleeve5. Threaded bushing6. Water filter7. Flow governor retaining clip8. Volumetric flow governor9. Venturi10.Water valve cover11.Temperature adjustment shaft

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.


CT-24page 1 of 1

rev 10/06



REPLACING ECO/TEMPERATURELIMITERMODELS: 1000P, 1600P, 1600H,

260PN, 425PN, 425HN

The ECOs/temperature limiters are overheat protectionsensors that will shut off all gas to the water heater inthe event of overheating.NoteNoteNoteNoteNote: If experiencing frequent pilot outages during orjust after use, first test the temperature limiter/ECObefore replacing it. See Bulletin CT-02 Thermocoupleand pilot test.

Tools

Philips head screwdriver, pliers and 22mm or adjust-able wrench

Replacing lower ECO/temperature limiter(not included on model 1000P)

1. Close installer supplied cold water isolation valve tothe water heater.

2. Locate the lower ECO on the ½” copper pipe exitingthe bottom left side of the heat exchanger (See Fig. 1).

3. Using pliers, disconnect both spade connections to theECO.

4. Using a 22mm or adjustable wrench, unscrew the ECOfrom the ½” copper pipe. Be careful not to overstrainthe copper pipe.

5. Install new ECO and reconnect wires from electromag-net and flue gas sensor. Wire orientation/polarity doesnot matter when making this connection.

6. Turn on cold water supply and return the water heaterto service.

Replacing upper ECO/temperature limiter

1. Close installer supplied cold water isolation valve tothe water heater.

2. Locate the upper ECO installed on the copper bend onthe upper right side of the heat exchanger (Fig. 2)

3. Using pliers disconnect both spade wire connectionsto the ECO.

4. Remove Philips head screw from the ECO bracket.5. Slide bracket and ECO away from the heat exchanger

and separate the bracket from the ECO. Do not loosethe bracket.

6. Insert new ECO into the bracket. If a new bracket isprovided with the ECO, there is no need to reuse theold bracket.

7. Slide ECO and bracket onto the mounting of the heatexchanger. Heat exchanger mounting should reside be-tween the ECO and bracket. (See Fig. 2)

8. Insert Philips head screw through ECO, heat exchangermount and tighten into ECO bracket.

9. Reconnect wires from the flue gas sensor and the ther-mocouple to the ECO. Wire orientation/polarity doesnot matter when making this connection.

10. Turn on cold water supply and return water heater toservice.

FIGURE 1

FIGURE 2


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rev 10/06



REPLACING ELECTRO-MAGNETMODELS: 1000P, 1600P

260PN, 425PN

Tools needed:

8mm or small adjustable wrench17mm or large adjustable wrench

Removing Electromagnet

1. Turn off gas to the water heater.2. Turn off water supply to the water heater using installer

supplied cold water isolation valve.3. Remove front cover of water heater as per instructions

in the installation manual.4. Using 8mm or adjustable wrench, loosen and remove

8mm nut and lead wire connected to electromagnet.5. Using 17mm or adjustable wrench, loosen larger 17mm

nut and remove electromagnet from gas valve assem-bly.

Installing Electromagnet

1. Insert replacement electromagnet into rear of gas valvewith spring and plunger end first.

2. Secure electromagnet into gas valve by tightening large17mm nut. Do not over tighten.

3. Thread lead wire with 8mm nut into electromagnet andtighten. Do not over tighten.

4. Reinstall front cover per instructions in the installa-tion manual.

5. Reopen water and gas supplies and check for gas leaksaround the electromagnet fittings. Tighten nuts fur-ther if a leak is found.

6. If no leaks are found, return heater to service.

Electromagnet location (view from bottom of heater)

FIGURE 1

8mm nut

17mm nut


CT-26page 1 of 1

rev 10/06



REPLACING ELECTRO VALVESMODELS: 1600H, 425HN

Tools

Philips head screwdriverPliers8mm or adjustable wrench.

Preparation

This procedure should be performed by alicensed gas technician

Before attempting to replace either electro valve,turn off gas supply to the water heater and turn ON(I) /OFF (O) switch to the OFF (O) position.

Removing Electrovalve

1. Locate the pilot and burner electro valves on thelower front of the water heater just to the left of thetemperature control knob and water valve (SeeFig.1).

2. Determine which electro valve is going to be re-placed. The upper electro valve (orange) is respon-sible for the pilot and the lower electro valve (green)is responsible for the burners.

3. Using pliers, disconnect wire at spade connection onelectro valve needing replacement.

4. Remove the two Philips head screws on each side ofthe Electrovalve.

5. Remove the electro valve from the gas valve housing.Be careful not to misplace the rubber o-ring thatseals the electro valve to the gas valve. If a new o-ring is provided with new electro valve, discard theoriginal o-ring. NNNNNOOOOOTE:TE:TE:TE:TE: If removing the pilot electrovalve, remove the pilot orif ice from the top of theelectro valve by unscrewing the 8mm orif ice nut withappropriate wrench (See Fig. 1). Do not lose thepilot orif ice.

Installing electro valve

1. If installing the pilot electro valve, insert and tightenthe pilot orifice nut from the old valve into the top ofthe new pilot Electrovalve.

2. Insert the rubber o-ring into the groove of the electrovalve housing on the gas valve. Failure to do this mayresult in a gas leak.

3. Insert electro valve into the electro valve housing onthe gas valve making sure to align the screw holesbetween the two.

4. Reconnect wire from the electronic control box tothe electro valve.

5. Turn on the gas supply to the water heater and chekcfor gas leaks.

6. Return the heater to service. If the unit does notignite at first, try cycling the water off and on tomake sure that air has been sufficiently bled fromthe gas line. NNNNNooooottttteeeee: It may take several cycling at-tempts to purge all the air out.

FIGURE 1

Burner electro valvePilot electro valve


CT-27page 1 of 1

rev 10/06



REPLACING CONTROL BOXMODELS: 1600H, 425HN

Tools

Philips head screwdriver, needle-nosed pliers.

Removing Ignition Unit

1. Close installer supplied cold water isolation valve towater heater.

2. Remove front cover of heater as per instructions inthe installation manual.

3. Remove single ignition wire connection (to sparkelectrode) from upper left corner of ignition unit.Unclip wire from bracket on top of ignition unit(425HN models only). (See Fig. 1)

4. Remove multiple wire connector from lower rightcorner of ignition unit by gently pulling outwardswith needle-nosed pliers. (See Fig. 1)

5. Remove screw with ground wire connection fromupper right corner of ignition unit. Metal bracketand ignition unit will drop down out of heater.

6. Remove ignition unit from metal bracket.

Installing Ignition

1. Insert tab on lower left of ignition unit into slot inlower left of bracket.

2. Mount ignition unit with bracket to heater by insert-ing screw into upper right hand corner. NNNNNooooottttteeeee: feedscrew through ground wire eyelet with washerbefore threading through ignition unit to heater. (SeeFig. 1)

3. Press multiple wire connector into lower right ofignition unit.

4. Push ignition wire into single terminal in top leftcorner of ignition unit. Clip wire into bracket on topof ignition unit (425HN models only).

5. Install front cover, open cold water supply and returnheater to service.

1600H, 425HN control box location

FIGURE 1

Control box


CT-28page 1 of 1

rev 10/06



REPLACING THERMOCOUPLE ANDFLUE SENSORMODELS: 1000P, 1600P

260PN, 425PN

Tools needed:Pliers, 8mm or adjustable wrench

Removing thermocouple and flue sensor1. Turn off gas supply to the water heater.2. Turn off water supply into the water heater using in-

staller supplied cold water isolation valve.3. Remove front cover as per instructions in the installa-

tion manual.4. The thermocouple is located in the center of the burner

rows directly behind the white ceramic spark electrode.Carefully, push down on the top on the thermocouplewith a flat head screw driver until it clicks out ofbracket. Pull down on thermocouple wires until it isfree from burner bracket. (Fig. 1).

5. Loosen and remove only the 8mm brass nut from elec-tromagnet on rear of gas valve. (Fig. 2)

6. Disconnect wire from thermocouple at the lower tem-perature limiter (ECO). (Fig. 2)

7. Disconnect wire from the flue gas sensor at the uppertemperature limiter (ECO). (Fig. 3)

8. Remove Philips head screw attaching the flue gas sen-sor to the draft hood. (Fig. 3)

9. Remove thermocouple & flue gas sensor with wiresfrom heater.

Installing thermocouple and flue sensorNNNNNooooottttteeeee: Replacement parts will come as two separateparts. Attach the thermocouple to the safety circuitwiring with the quick connect plug before proceeding.

1. Attach flue gas sensor to the upper right hand side ofthe draft hood using Philips head screw. Flue gas sen-sor should be on the inside of the draft hood in orderto properly sense flue gas spillage. (Fig. 3)

2. Connect wire connection at upper temperature limiter(ECO). (Fig. 3)

3. Feed wires down the right hand side of the water heaterand secure in wire tie on the lower right side of heaterchassis. Make sure that none of the wires rest againstthe copper heat exchanger.

4. Connect wire connection from thermocouple to lowertemperature limiter (ECO). (Fig. 2)

5. Feed replacement thermocouple from underneath burn-ers into burner bracket. Push into bracket until it snapsin place. (Fig. 1)

6. Thread 8mm nut end from flue sensor wire into elec-tromagnet and tighten. NNNNNooooottttteeeee: Do noDo noDo noDo noDo not ot ot ot ot ovvvvver tighter tighter tighter tighter tighten.en.en.en.en.

7. Reinstall heater cover as per instructions in the instal-lation manual.

8. Reopen water and gas supplies and return heater toservice.

Thermocouple location

FIGURE 1

Thermocoupletip(press down)

Electromagnet Location (view from bottom of heater)

FIGURE 2

8mm nut

Lead fromupper ECO

Lead fromthermocouple

Flue sensor Location (view from right side of heater)

FIGURE 3

Flue gassensor

Lead from fluegas sensor

Lowertemperaturelimiter

Uppertemperaturelimiter

BBT North America CorporationBosch Group Bosch Water Heating340 Mad River ParkWaitsfield, VT 05673Telephone 800-642-3111Fax (802) [email protected]

service bulletin booklet - bosch climate · on how to clean pilot assembly and orif ice. 3. if...

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