G. Design Air Flow

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When I use delta T 20F for supply fan, the CFM stays the same and the cooling load is up 60% and heating load is slightly lower. Any clue?

Is there a correct way to put in the Delta T 20F (after I set default and not using fan static pressure) and eQuest will calculate the correct CFM?

Thanks for the help.

Walter W. Chan, P.E., LEED AP

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Joined: 2011-09-30
Reputation: 0

The delta T G. is referring to a 20 degree delta between room
cooling setpoint and supply air temperature. For example:

Room Cooling Setpoint = 75 ?F

20 ?F delta from G. = -20 ?F

Supply Air Temperature = 55 ?F

A 20 degree fan delta T would be a MONSTER of a fan..

Robby Oylear, LEED? AP

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Joined: 2010-11-03
Reputation: 0

To follow up on what Robb said, the fan delta T is the heat gain across the fan from the fan motor.

You input your supply air temperature in this window:

Vikram Sami, LEED AP

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Joined: 2011-09-30
Reputation: 0

?and to follow up on what Vikram said, eQUEST is sizing flows off the system SA temp and each zone?s indoor design temperatures. Indoor design temps do not necessarily correspond to the settings in the thermostat schedule; users need to verify both. The screen below is where you specify design temps. The spreadsheet view is helpful for adjusting all zones quickly:


Dakota Kelley's picture
Joined: 2011-09-30
Reputation: 1