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.

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