[Equest-users] DOAS with dehumidification

[Michael Campbell via Equest-users]

Thanks for the reply Nick.  The air will be conditioned by a secondary
system.  The system is designed so the DOAS/ERV supplied "neutral" air
(~75F) to apartments and the space loads are met by split system heat pumps
in the apartments.  So, if the system is dehumidifying, it is possible that
the DOAS could supply air at ~60F, and the assumption is that the heat
pumps in the apartments will be able to handle that additional load.

On Mon, May 23, 2016 at 2:04 PM, <Nicholas.Caton at schneider-electric.com>
wrote:

> Mike,
>
>
>
> Ref: Volume 2: Dictionary > HVAC Components > SYSTEM > Airside Control >
> Humidity Control > MAX-HUMIDITY
>
>
>
> To my understanding, no explicit mode of doe2 dehumidification DOESN’T
> assume some form of reheat to deliver the specified/derived supply air
> temperature.  In turn, I’m not certain whether it’s going to be easy to (a)
> force “sub-cooling” without the use of a custom COOL-SET-SCH schedule
> (that’s where I’d suggest you go next with this), deriving the anticipated
> additional coil operations from the weather data and/or the model you’ve
> already built, and (b) transfer that “sub-cooled” air reheating load to the
> other systems in your model.
>
>
>
> Fair question before you dive further:  is the associated reheating going
> to occur somewhere in the building anyway (i.e. by other systems), and as
> such would it be a major stretch to simply permit your dummy-zone DOAS
> perform that reheating?  If that’s a reasonable analysis, you might not
> need to do anything else.
>
>
>
> Of course, presence of ERV just layers on the fun.  Frankly when ERV gets
> involved, that’s one of my primary drivers for shifting away from a dummy
> zone approach and approximating the DOAS system (and its ERV components)
> into the other conditioning systems to more directly capture what’s coming
> off the exhaust/relief stream.
>
>
>
> ~Nick
>
>
>
>
> ------------------------------------------------------------------------------------------------------------------------------
>
> *Nick Caton, P.E.*
>
>   Senior Energy Engineer
>   Energy and Sustainability Services
>   North America Operations
>   Schneider Electric
>
> D  913.564.6361
> M  785.410.3317
> E  nicholas.caton at schneider-electric.com
> F  913.564.6380
>
> 15200 Santa Fe Trail Drive
> Suite 204
> Lenexa, KS 66219
> United States
>
> [image: cid:image001.png at 01D189AB.58634A10]
>
>
>
>
>
> *From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
> Behalf Of *Michael Campbell via Equest-users
> *Sent:* Wednesday, May 18, 2016 7:37 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] DOAS with dehumidification
>
>
>
> Hello,
>
> I am trying to model a DOAS that supplies conditioned outside air to
> dwelling units.  It also has an ERV.  I have created a dummy zone with no
> loads and made the setpoints for the dummy zones my desired heating and
> cooling supply air temperatures (73F for heating and 75F for cooling).
> However, the DOAS also has dehumidification in which it will operate in
> cooling mode to dehumidify at >60% RH.  There is no reheat coil, so when
> the system is dehumidifying, the supply air temperature should drop below
> the setpoint.
>
> Here is the issue I'm having.... when I look at my hourly reports, I can
> see that the air leaving the cooling coil will drop down to about 60F at
> times when the system is dehumidifying.  However, the dummy space is still
> showing a space temperature of ~74F.  How is this possible?  Does anyone
> have any ideas?
>
> Thank you,
>
> Mike C
>
>
> ______________________________________________________________________
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