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Overview of Diagnostic Testing Equipment Used in RESNET standardsBill SpohnPresident, Owner, TruTech Tools, LTD
2020 RESNET Building Performance Conference
Scottsdale, AZFebruary 26, 2020
Bill Spohn� Bacharach, Inc.
� Testo, Inc.
� TruTechTools, LTD� BS & MS ME� Professional Engineer
� Standards committees
� Consultant, trainer
� Podcaster: � Building HVAC Science� RESTalk
2019
The Team that makes possible what I do!
Our topic
� Tools and test instruments that apply in RESNET standards 310 (pending) and 380
� NOTE:
�Use RESNET website as you source for info on the standards
� https://www.resnet.us/about/standards/resnet-ansi/
� Overview of 380 changes in 2019 version:� www.bit.ly/380-2019-info
Which standards?
� Standard 310. (proposed) is the standard for grading the installation of HVAC systems with 5 steps
� www.bit.ly/310-DRAFT
� Standard 380 is the Standard for Testing Airtightness of Envelopes, Ducts Systems; and Airflow in Mechanical Ventilation Systems
� 2016: www.bit.ly/380-2016� 2019: www.bit.ly/380-2019
Applicability of the standards
� ENERGY STAR National Program Requirements Rev 10 is available for use now and will be required for ENERGY STAR Certified Homes permitted on or after Oct. 1, 2020.
� It integrates the new ANSI/ACCA/RESNET Standard 310, as an option, once completed.
What is standard 310?
� Evaluation of installation quality of Unitary HVAC systems.
� Comprised of five tasks –� a design review� a total duct leakage test� a Blower Fan volumetric airflow test� a Blower Fan watt draw test� a non-invasive evaluation of refrigerant charge
� The five tasks are designed to be completed in sequence and upon completion of each task, the results are evaluated for compliance with specified thresholds.
Where does standard 310 apply?
� Unitary HVAC Systems
� Air conditioners and heat pumps up to 65 kBTUh (5.4 Tons)
� Furnaces up to 125 kBTUh
� Detached one- and two-family Dwellings, Townhouses, as well as in Dwelling Units and Sleeping Units that have their own HVAC system separate from other units
� It is intended for use by home energy raters, energy auditors, code officials, or HVAC contractors.
Standard 310 Stop or Go Approach
310:Section 4:Evaluate the design
� Lots of detail collection
� Manual J and S are employed
� Rating of data collected against the standard’s requirements.
310:Section 5:Total Duct Leakage
� Measure in accordance with RESNET Standard 380� Coming up!
� Rating
310:Section 6:Blower CFM
� 6.4 Pressure Matching Method
� 6.5 TrueFlow Grid
� 6.6 Flow hood
� 6.7 Static Pressure Tables
� Or
� On Board Diagnostic system output
� Sec. 8.6 of ASTM E-1554-13
� Appendix A ASHRAE 152-2004
� CEC RA3.3 (2016 Reference Appendices)
6.4 Pressure matching
� In place of door, on an extension, at central return
�Match the NSOP
TrueFlow® Plate (Pitot Array) or Flow Grid� How it works
� Like multiple Pitot Tubes yielding an average velocity sampled over large area
� Benefits� Fast to set up, adjustable� Central return or in filter slot� Very close to “run conditions” (NSOP)
� Limitations� Needs specific digital manometer� If >1 central return, need one
simultaneously in each return
� Applications� System airflow
Cost ~$895 + precision manometer
The TrueFlow® Air Handler Flow Meter
Passive intercept flow measurement
• Obstructions within 6” upstream or 2” downstream that block air flow may reduce accuracy
• If there is an obstruction and using a spacer, place spacer is directly in front of the obstruction
• If installed downstream of a 90 degree bend and using a spacer orient it so spacer is on the inside corner of the bend.
The Energy Conservatory TrueFlow® Air Handler Flow Meter
TrueFlow® Air Handler Flow Meter is a registered trademark of The Energy Conservatory
6.6 Flow hood
� Accuracy +/-3 % + 7 CFM
� Range must suit your system air flow range
� Place over each Return Grill and sum
� Measure for 10 seconds
� Correct for back pressure
Capture Devices in general� Flow hoods
� Typically Pitot array
� Benefits� Fast to set up and use� Captures all the air, if hood skirt is right� Snapshots� Multifunction meters� 3 ranges : 500, 1250 & 2500 CFM
� Limitations� Accuracy is mass dependent/corrected� Back pressure compensation� Flow straighteners
$1500 - $2200 - $3200
Testo 420
� Great price point: ~$2162� Lightweight� BlueTooth to app � Swirl reducing grid built in to skirt� Temperature, Humidity & Barometric readings *� Detachable precision manometer
� * used internally for corrections
ACIN Powered Flow HoodFlow Finder MK2
• Internal fan and sensor compensates for back pressure
• Up to 500 CFM supply or return• High accuracy• Single piece• Light weight (5 lbs)
COST = $2950
6.7 Static Pressure Tables
� OEM “Fan Curves”
Static Pressure Tip
� How it works� Static or balloon pressure of air is delivered to
a pressure sensor
� Benefits� Easy to use, cost effective
� Limitations� Air Density correction considerations � Does not directly equate to airflow
� Applications� In duct measurement
Price $ 20 each, usually need 2 plus a decent manometer
Connect hose here->
Static
Static
Total External Static Pressure
� Manufacturer profiles each heat exchanger or evaporator coil� By measuring across system components (coil or HX)
� CFM � Pressure drop
� Creates a table of CFM at ESP for various configurations� The industry standard for TESP in equipment design is ½”wc,
ranges from 0.3-1.0” H2O are possible � ECM motors produce odd results
RESOURCES� Free guide to testing TESP
� www.bit.ly/TTT-ESP
� 20 Minute video lesson� www.bit.ly/ESP-VIDEO
� Look for Energy Star Videos on ”How to”� www.bit.ly/380videos
CFM Grade
Section 7Blower Watt Draw
� +/- 2% or +/- 10 W
� 7.4 Plug in Watt Meter
� 7.5 Clamp on power meter
� 7.6 Analog Utility meter
� 7.7 Digital Utility meter
� OROn board Diagnostic System
Plug in watt meter
Clamp on power meter
Section 8System Charge
� 8.4 Non Invasive system test� Thermometer (+/- 1.8 deg F)
� OA DB
� Humidity probe (+/- 1.8 % +3%)� RA WB & DB
� Pipe clamp probe (+/- 2.3 deg F)� Liquid Line Temp
� 8.5 Weigh the charge
Standard 380
Standard for Testing:Airtightness of Building EnclosuresAirtightness of Heating & Cooling Air Distribution SystemsAirflow of Mechanical Ventilation Systems
Blower door test: Airflow calculated from manometer pressure
Duct leakage test: Airflow calculated from manometer pressure
Here’s where it gets complicated……
“Which equipment is RESNET approved?”
� The airflow (at outlet terminal) is permitted to be measured using a Powered Flow Hood (Section 5.2.1) or using a Bag Inflation Device (Section 5.2.2).
� Standard 380 sets the specifications for the equipment used to perform the tests covered by that standard.
� As long as the testing equipment meets the technical specifications for the type of equipment specified for the test, the equipment can be used to perform the test.
� RESNET does not endorse or approve specific pieces of equipment.”
� ‘testing volumetric airflow”: CFM� 3 choices of where you can measure
� What is being assumed here…….?
Ventilation System MeasurementsAt an air INLET TERMINAL
by the book (Standard 380)
� Powered flow hood
� Retrotec Acin FlowFinder®
� Duct tester adapted to be a powered flow hood
� FlowBlaster® <- now out of production
� Air Flow resistance device
� TEC Exhaust Fan Flow Meter
� Use only if there is ONE BRANCH� Only when box pressure is between 1-8 Pa
� Passive Flow hood
� Tolerance of +/-5% or +/-5 CFM
� Only when back pressure is < 8 Pa
Ventilation System MeasurementsAt an air OUTLET TERMINAL
by the book (Standard 380)� Powered flow hood
� Acin FlowFinder® Retrotec
� FlowBlaster® <- now out of production
� Bag inflation device: must make your own� Airtight perimeter seal� Plastic bag of known volume� Frame to hold the bag open� Shutter that controls airflow into the bag� The thickness of the bag shall be selected such that three or more
measurements of a single outlet terminal produce results that are within 20% of each other.
� Volume of the bag chosen so bag fills within 3 to 20 seconds.
The PVCD� The polymeric
volumetric capture device
� AKA The garbage bag
� Works by timing how long it takes to fill a known volume with air
� Use a “pressure spike” inside bag to indicate full
Garbage Bag Flow
0255075
100125150175200225250275300325350375400425450475
1 1.5 2 2.5 3 3.5 4 5 6 7 8 8.5 9
Seconds to fill bag
CFM
33 gallon55 gallon
Bag Inflation Device: Truly capturing it.
AirProbe (Averaging Flow Station)� How it works
� Similar to an averaging Pitot Tube
� Benefits� Easy to use, cost effective
� Limitations� MUST be exact size of duct� Denser air has more mass, thus more pressure at a given velocity� “Lower velocity” limits only with precise manometer with calculation� 1” diameter hole to drill and plug� Must use specific equation, not a Pitot Tube� Reading changes with orientation to up stream elbows� Other look-a-likes available, use each with extreme care
� Applications� In duct measurement
Price <$100 plus manometer $200, about $300 total
CFM = 800Area = 1 sq ftVel = 800 FPM
dP = (Vel / Kv) 2
dP = 0.102 IWC
Or: www.bit.ly/Kele-Calc
www.redcalc.com/red-calc-free/
Dwyer MAFS
A different product!
� Air velocity calculation� 1096.2 x Cp x SQRT (Pv/D)� Pv = pressure in IWC� D = Air Density in Lbs/Ft3� Cp depends on MAFS length� D = 1.325 x Pb / T
� Pb = Barometric pressure in IN HG� T = Absolute Temp in Kelvin
� Kelvin = F + 460
� Location in straight run� 10 to 15 DD upstream and 5 DD downstream� 8” duct means 6.6 to 10 feet UP and 3.3 feet down
MAFS
PAFSUse only with a reference
Powered Flow HoodFlow Finder MK2
• Internal fan and sensor compensates for back pressure
• Up to 500 CFM supply or return• High accuracy• Single piece• Light weight (5 lbs)
COST = $2950
Manometers matter� Oftentimes pressure is used as the core measurement
in airflow� Know the range and necessary accuracy of your
measurement� Low cost manometers may give you 100% error if used
in the wrong application� Just because you see a stable number does not mean
the reading is accurate.� If pressure is off by 10%, calculated flow is off by 5%
Exhaust Fan Flow Meter,’,’,’,’ ,l ,,’’,’,’,’,
50Pa6.2
Exhaust
52C F M
DG-700
InputInput
T
DM32
RefInputT
Ch A Input - monitoring the pressureCh B Ref – Calculating the results
Channel A Must be between 1 – 8 Pa
Tubes “T” together
Exhaust Flow measurement experiment with Kele
AirProbes
courtesy of Steve Rogers
Flex duct was around a cylinder to insure it had a bend radius equal to the duct diameter like the manufacturer specifies. The segmented adjustable elbow was set to 90 degrees.
1-888-224-3437 [email protected]
SPECIAL OFFER for RESNET CONFERENCE ATTENDEES ONLY!
Use coupon code:
testo20resnet20
For 20% off your order on any testo products
May not be combined with any other coupon, offer or promo.Expires 3-31-20
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