[Equest-users] DHW Heat Pumps

[Robby Oylear]

Even if you define the space it's in (see the LOCATION parameter), the help
file indicates that no losses from the tank UA are attributed to the actual
zone load.  I agree with Yoni that eQUEST is not smart enough to do this
calculation for you.

If you felt like getting more complicated you may be able to determine the
cooling load that should be attributed to the space from the heat pump
through hourly reporting, then create a custom 8,760 hourly schedule using
Rocky Mountain Institute's energy modeling input translator tool.  You
could then apply the load to the space through the internal loads tab and
give it a negative Internal Energy Source with TYPE = PROCESS.  I haven't
verified if negative values under this input actually count as cooling
loads, but it should be fairly simple for you to test it out.

Robby Oylear, PE, LEED AP

*Mechanical Engineer*

*Senior Energy Analyst*

* *

*D* 206-788-4571

*www.rushingco.com* <http://www.rushingco.com/>

On Thu, Aug 2, 2012 at 8:03 AM, Yoni Pollak <ypollak at gtp-eng.com> wrote:

> I don’t think the program is that smart since I don’t see a place where
> you assign a space to the DHW heat pump.  I.E.  eQuest doesn’t know which
> space the dhw heater is located.  So unless I’m missing something, it looks
> like the program does model it as a split system with the condenser
> outside.  ****
>
> ** **
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> Yoni G. Pollak, PE****
>
> (T) 770-622-2270****
>
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>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Daniel Wright
> *Sent:* Thursday, August 02, 2012 10:54 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] DHW Heat Pumps****
>
> ** **
>
> Hello all,
>
> I'm trying to include a DHW heat pump into some of my models and am
> confused about some of the results I'm seeing. It seems that the only
> option for DHW heat pumps in eQuest is that the heater and its condenser
> are together on the same unit (no split/external condenser). This seems
> fine, but I thought that if this is the case, then the annual heating and
> cooling energy use should be affected by the DHW heat pump. In particular
> it seems that in winter the space heating energy use should go up since the
> DHW heat pump is extracting heat from the space it's in, requiring the HVAC
> system to provide more heat, and in summer the space cooling energy use
> should go down for the same reason. But I see no change in the heating or
> cooling energy when we run the DHW heat pump.
>
> Can someone explain why this is the case? Am I missing something?
>
> Dan****
>
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