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

Rob Hudson rdh4176 at gmail.com
Wed Mar 28 05:46:38 PDT 2012

Without spending time on  your input files, my first guess is to check our
heat exchanger fan static pressure.  i had a similar situation on a model i
was working on in the past few months, and once i entered in 0 for my fan
energy (my heat exchanger worked as a DOAS for my system, and therefore the
supply fan was accounting for the HX fan) everything went back to normal.

Hope you find this helpful.


On Wed, Mar 28, 2012 at 6:31 AM, Jason Quinn <jason.e.quinn at gmail.com>wrote:

> 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.
> Jason
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Rob Hudson
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