[Equest-users] Heat Exchanger added to simple SD model with DOAS added - 3000% increase in energy for fans

Sami, Vikram Vikram.Sami at perkinswill.com
Fri Mar 30 07:50:06 PDT 2012

The issue might be that you haven't specified any controls on your ERV. Its on float with no capacity control. 

On another note - one of the issues with the DOAS-Dummy zone approach is when you have a heat recovery systems attached to the DOAS. When you have a system borrowing air from another system, eQUEST cannot model heat exchange between the two. You need to figure out a way to trick the program into accounting for the actual heat exchange (possibly with a phantom internal load in the dummy zone).

Hope this helps. 

Vikram Sami, LEED AP BD+C
Sustainable Design Analyst
1315 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462    f: 404.892.5823       e: vikram.sami at perkinswill.com   www.perkinswill.com
Perkins+Will.  Ideas + buildings that honor the broader goals of society

-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Jason Quinn
Sent: Wednesday, March 28, 2012 6:32 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Heat Exchanger added to simple SD model with DOAS added - 3000% increase in energy for fans

So this is pretty odd I'm running a simple SD wizard generated office building and adding the DOAS to it in DD edit mode. The DOAS works as expected (Thanks to Brian Fountain) slightly lowering the space heating & increasing vent. Fans. over a case without the DOAS. Now when I add a heat exchanger to the DOAS (PVVT) it causes the fan usage to go nuts increasing Vent. Fans from 0.2E6 kWh to 6.5E6 kWh while the space heating drops from a resonable (I think) 3.7E9BTU to 0.4E9BTU.

If someone could point me in the right direction to sort out why the heat exchanger is causing such a huge increase I'd really appreciate it.

I have played with the DOAS fan schedules and can effect the increase downwards but not enough to make this reasonable. I've attached the DOAS with Heat exchanger .pd2 & .inp file. To see the results without the heat exchanger just turn it off. I'll attach my weather file as well so that it's easier to look at my file.

Thank you for the help.

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