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Fan Efficacy
Fan efficacy is how many watts the air handler’s blower uses for every CFM of air it moves. We measure the blower’s watt draw and the system airflow at the same time, then divide: watts ÷ CFM = W/CFM. Lower is better.
Blower watt draw on a plug-in meter: 397 W.
Maximum fan efficacy
Measured at maximum fan speed, in the same visit as the airflow test.
| Air handler | Maximum | Code |
|---|---|---|
| Gas furnace | 0.45 W/CFM | §150.0(m)13 |
| Gas furnace manufactured before July 3, 2019 | 0.58 W/CFM | §150.0(m)13 |
| All other air handlers (heat pump, fan coil) | 0.58 W/CFM | §150.0(m)13 |
Example: a blower drawing 397 W while moving 1,000 CFM is 0.40 W/CFM — passing for any air handler. On a performance CF1R, the value that counts is the one on your CF1R. See System Airflow for how CFM is measured.
What to expect
How we measure watt draw when you hire us.
Watt draw
Measured at the air handler
With the system running at maximum fan speed, we measure the blower’s power with a plug-in watt meter where the unit is cord-connected, or with a true-RMS meter on hardwired units. The reading is paired with the airflow measured during the same test.
The code
Click a section to read the actual code language, or open it in the official CEC document.
§150.0(m)13Maximum fan efficacy (new construction)
B. Single zone central forced air systems. Demonstrate, in every control mode, airflow greater than or equal to 350 CFM per ton of nominal cooling capacity through the return grilles, and an air-handling unit fan efficacy less than or equal to the maximum W/CFM specified in Subsections i or ii below… i. 0.45 W/CFM for gas furnace air-handling units. ii. 0.58 W/CFM for air-handling units that are not gas furnaces.
Exception 2: Multispeed compressor systems or variable speed compressor systems shall verify air flow (cfm/ton) and fan efficacy (Watt/cfm) for system operation at the maximum compressor speed and the maximum air handler fan speed.
Exception 3: Gas furnace air-handling units manufactured prior to July 3, 2019 shall comply with a fan efficacy value less than or equal to 0.58 w/cfm…
Exception 2: Multispeed compressor systems or variable speed compressor systems shall verify air flow (cfm/ton) and fan efficacy (Watt/cfm) for system operation at the maximum compressor speed and the maximum air handler fan speed.
Exception 3: Gas furnace air-handling units manufactured prior to July 3, 2019 shall comply with a fan efficacy value less than or equal to 0.58 w/cfm…
RA3.3.3.4.3Compliance criteria
(b) The calculated value for fan efficacy (Watt/cfm) shall be equal to or less than the fan efficacy compliance criterion specified in the Standards or on the Certificate of Compliance as applicable.
Schedule fan efficacy testing.
Verified together with system airflow once the system is running.