[Equest-users] heat recovery bug

[Doug Maddox]

I think I found a bug with the ERV feature in eQuest related to
temperature control.  My input is as follows:

 

   RECOVER-EXHAUST = YES

   ERV-RECOVER-TYPE = ENTHALPY-WHEEL

   ERV-SENSIBLE-EFF = 0.75

   ERV-LATENT-EFF = 0.75

   ERV-RUN-CTRL = OA-EXHAUST-DT

   ERV-TEMP-CTRL = MIXED-AIR-RESET

   ERV-CAP-CTRL = MODULATE-HX

   ERV-HX-KW =   0.207

   ERV-FANS = HVAC-SUPPLY/RETURN 

   ERV-OA-STATIC =    0.5

   ERV-EXH-STATIC = 0.5

   ERV-FROST-CTRL = USE-CAP-CTRL

 

The system shows heating savings as expected, and cooling savings during
summer periods, but during winter there is a large cooling penalty.
Hourly reports show an unexpected cooling load during winter night mode
operation.  If I set ERV-OA-STATIC to zero, that cooling load goes away.

 

If I change to a fan located in the ERV, the unexpected cooling load is
still absent:

 

  ERV-FANS = SELF-CONTAINED

  ERV-EXH-KW/FLOW = 0.002

 

Thus, it appears that the heat gain due to friction in the heat wheel is
not taken into account for the OA setpoint during night mode when
ERV-FANS = HVAC-SUPPLY/RETURN.  Has anyone else seen this problem?

 

The SELF-CONTAINED option appears to be a work-around, but it is not as
convenient for add-on heat wheels.

 

 

Thanks,

Doug Maddox, PE

THE WEIDT GROUP
  
5800 Baker Road
Minnetonka, MN 55345
T 802-262-1033
F 952.938.1480
www.twgi.com <blocked::http://www.twgi.com/> 
DougM at twgi.com <blocked::mailto:DougM at twgi.com> 

 

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