[Equest-users] DOAS results

[Brian Fountain]

  Remember that eQUEST doesn't /really/ do DOAS yet.  All it does is set 
the OA temperature for the borrowing zone using the OA-FROM keyword to 
the RA temperature of the "lending" system (which is why it has to come 
first on the system list).

I really hope this changes in future releases!

On 10/19/2010 7:25 PM, Carol Gardner wrote:
> 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 <mailto: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/
>
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>     **Your 2030 Challenge Partner***
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>
> -- 
> Carol Gardner PE
>
>
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