[Bldg-sim] HRV question

[Karen Walkerman]

Hi Franc,

I too have spent many hours struggling with ERVs in eQuest.

First of all, a sensible heat recovery ventilator will not recover much
energy during the cooling season.  Remember that energy recovery ventilators
recover nearly no energy at dT less than 5F.  Also, in the summer, the
moisture content of the air is usually higher, so much of the energy
available to be recovered is latent.

Second, running an HRV requires additional fan power.  I have found eQuests
default fan power to be a bit high, so check the these numbers to make sure
they are appropriate for your project.

Third, if a building is equipped with an HRV, but no economizer, the HRV
will be recovering energy when it is not desired.

If the HRV has a bypass for outdoor air, you can set the HRV controls to
allow bypass of OA, set ERV-CAP-CTRL to "bypass OA".  If the air handler
also has an economizer, set ERV-RUN-CTRL to "when minimum OA"

This should bring the cooling energy close to the baseline (and perhaps
slightly lower).  The fan energy will increase.  Savings will vary by
climate.  You may want to experiment with a sensible heat exchanger, if it
is appropriate for the application.  We usually use total energy recovery
wheels, unless they are inappropriate for the application (lab buildings,
for example).


hope this helps.

~karen~

On Feb 13, 2008 10:12 AM, Sever, Franc <SeverFranc at karpinskieng.com> wrote:

>  Hello All,
>
> I am fairly new to eQuest and this is my first post to this group.  I am
> modeling a university building which has an air handling unit with a heating
> coil and chilled water coil supplied by campus steam and chilled water.  My
> problem is that when I add energy recovery to the air system the space
> heating energy goes down but my cooling energy goes up as compared to the
> proposed building without energy recovery.  I am using a sensible HX with OA
> DT of 10 F, OA heating and cooling, mixed air reset, and modulating the hx.
> I hope all this makes sense, but I also tried setting the energy recovery to
> only OA heating and the cooling load still went up considerably.
>
> Any help would be greatly appreciated.  Thank you and have a great day.
>
> Franc J. Sever
> Engineer, Mechanical
>
> Karpinski
> ENGINEERING
> 3135 Euclid Avenue
> Cleveland, OH  44115
> P  216-391-3700
> F  216-391-0108
> E * FSever at karpinskieng.com*
>
>
>
> _______________________________________________
> Bldg-sim mailing list
> http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to
> BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20080213/50253297/attachment-0002.htm>