Enthalpy Wheel Bypass

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Hello All,

I am trying to optimize an enthalpy energy recovery wheel in a VAV AHU with an economizer. The AHU design allows for full bypass of the enthalpy wheel in economizer mode - I would like to model this static pressure reduction in eQUEST.

Currently the wheel operation is set to "When Minimum OA" to take advantage of economizer operation. Can anyone confirm if eQUEST bypasses the wheel when it is "off" in this operation mode? If not, is there a way to control the wheel so that OA and EA bypasses the wheel during economizer mode to eliminate the wheel pressure drop.

Thanks in advance for your help.

Seth P Spangler, PE, LEED AP BD+C

Seth P. Spangler's picture
Joined: 2012-11-12
Reputation: 0

Hi Seth,

I suggest you create custom hourly reports. The screen shot below shows the hourly selections that I think will help answer your question. The "Ratio of outside air to total supply air" should tell you when your economizer is active. I'm not sure what "Outside fan power (kW)" is so it may or may not be helpful. I believe "ERV Power of integral fans (kWh)" will be your extra ERV fan energy whether you have SELF-CONTAINED fans or penalize the main air handler fans with additional static pressure, but I'm not sure of this. If you find that you always have the fan energy penalty, one thing you can try is to change the ERV-CAP-CTRL to BYPASS-EXHAUST. Additionally, you can combine the static pressure or ERV fan power for both the make-up and exhaust sides and entire the value on the exhaust side only. That way, when the ERV bypasses exhaust, all the fan power or extra static pressure should be removed as well. (Note - I haven't tried this before.) Let us know what you find out.


[cid:image003.jpg at 01CDBE5A.6C3AF670]

[Senior Energy Engineer 28Jun2012]

Bill Bishop's picture
Joined: 2012-02-25
Reputation: 7