[Equest-users] DOAS results

[Carol Gardner]

Are you willing to share your .inp and .pd2 input decks? I would take a
quick look if you are.

Carol

On Tue, Oct 19, 2010 at 12:40 PM, Fleming, Joe <joe.fleming at tlc-eng.com>wrote:

>  I know this topic has been beaten like..., but the results I have been
> getting for the ## hours on a model with several DOAS's are horrible,
> (getting a little delirious at this point).  There is a DOAS for each system
> with a different schedule than the next.  Each DOAS has an ERV which
> operates with a DH of 2.0btuh/hr in cool/heat and float.
>
> I feel like the problem is within the dummy zone or the schedules.
>
> When I assign the DOAS air to the SZRH unit as OA from System the cooling
> load shoots up by about 50%, (even when I remove the ERV the results are
> similar, increased cooling).
>
> The building is in a moderate climate zone.
>
> The DOAS fan schedule is set to on at the same time as the SZRH unit.
>
> The heating energy is reduced when I assign the DOAS.
>
>
>
> The problems I see are, to list a few;
>
> The dummy zone has all of its hours outside of the throttling range no
> matter how it is assigned and no matter what the t-stat schedule I assign.
>
> The load doesn't budge once I remove the DOAS from the model, only when I
> add it to the SZRH unit as OA from system.
>
> The DOAS does not show any heating load, only cooling load all year long
> (again moderate climate with cold seasons).
>
> DOAS's have been done before without this problem, maybe adding too much
> info this time.
>
>
>
>
>
> **How is the DOAS operating in eQuest?*
>
> Taking a stab I assume it is bringing in the OA and cooling it or heating
> it to whatever the temperature set-points are.  Depending on the schedules
> the temp could be floating most of the time.  The air is then brought into
> your secondary system at set-point or floating point.  The OA from the zones
> attached to the secondary system are replaced by the OA from the DOAS. (?)
> Then the secondary system does its thing as usual.
>
> (Not sure what is happening with the dummy zone?  Does DZ care it gets any
> air?  Looks like it does because of the unmet hours.  Does the secondary
> system pick up the air from the DOAS after it has traveled through a space
> and picked up load?  The dummy zone has no load but it's temp is always
> above 85.)
>
>
>
> Now for the cooling to be increasing, the air must be coming in to the
> secondary system warmer than usual during cooling hours.  (usual being the
> raw temperature of uncond outdoor air).   But the results seem extreme.
>
> For the heating to be decreasing the air must be coming in warmer than
> usual for the secondary system, which it is based on SS-O.
>
>
>
> Does anyone have experience with this and what could be going wrong?
>
> **Or, can someone link me to a basic DOAS goby?  *
>
> I have searched the archives but many of the DOAS questions have gone
> unanswered in the past.
>
>
>
> Thank You
>
>
>
> *Joe Fleming*
>
> *E.I., LEED AP BD+C, BEMP*
>
> *Mechanical Engineer I*
>
>
>
> *TLC Engineering for Architecture
> **Your 2030 Challenge Partner***
>
>
>
> 800 Fairway Drive, Suite 250
>
> Deerfield Beach, FL 33441-1816
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>
> phone:
>
> 954-418-9096
>
> fax:
>
> 954-418-9296
>
> direct:
>
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>
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>
> www.tlc-engineers.com
>
>
>
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>
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-- 
Carol Gardner PE
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