Learn about the variety of tools and test instruments that apply in RESNET standards 310 (pending) and 380. We'll cover the proper procedures as well as pros and cons of various devices.
2. BillSpohn
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!
3.
4. 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
5. 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 forTesting Airtightness of
Envelopes, Ducts Systems; andAirflow in MechanicalVentilation
Systems
2016: www.bit.ly/380-2016
2019: www.bit.ly/380-2019
6. 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.
7. 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.
8. Where does
standard 310
apply?
Unitary HVAC Systems
Air conditioners and heat pumps up to 65 kBTUh (5.4Tons)
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.
10. 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.
14. 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
15. 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.
16. The Energy ConservatoryTrueFlow® Air Handler Flow Meter
TrueFlow® Air Handler Flow Meter is a registered trademark of The Energy Conservatory
17. 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
18. 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
19. 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
20. ACIN Powered Flow Hood
Flow 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
22. 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
23. 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
24.
25.
26.
27. 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
29. Section 7
BlowerWatt
Draw
+/- 2% or +/- 10W
7.4 Plug inWatt Meter
7.5 Clamp on power meter
7.6 Analog Utility meter
7.7 Digital Utility meter
OR
On board Diagnostic System
32. Section 8
SystemCharge
8.4 Non Invasive system test
Thermometer (+/- 1.8 deg F)
OA DB
Humidity probe (+/- 1.8 % +3%)
RAWB & DB
Pipe clamp probe (+/- 2.3 deg F)
Liquid LineTemp
8.5 Weigh the charge
33. Standard 380
Standard for Testing:
Airtightness of Building
Enclosures
Airtightness of Heating &
Cooling Air Distribution
Systems
Airflow 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……
34. “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.”
35. ‘testing volumetric airflow”: CFM
3 choices of where you can measure
What is being assumed here…….?
36. Ventilation System Measurements
At 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
37. Ventilation System Measurements
At 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.
38. 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
41. AirProbe (Averaging FlowStation)
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
42. CFM = 800
Area = 1 sq ft
Vel = 800 FPM
dP = (Vel / Kv) 2
dP = 0.102 IWC
Or: www.bit.ly/Kele-Calc
45. 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 = AbsoluteTemp 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
PAFS
Use only with a reference
46. Powered Flow Hood
Flow 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
47. 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%
48. Exhaust Fan Flow Meter
,’,’,’,’ ,l
,,’’,’,’,’,
DG-700
InputInput
T
DM32
RefInput
T
Ch A Input - monitoring the pressure
Ch B Ref – Calculating the results
Channel A Must be
between 1 – 8 Pa
Tubes “T” together
50. 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.