[bldg-sim] equest recovery

Graham & Megan hamnmegs at ozemail.com.au
Thu Feb 2 12:00:38 PST 2006


Extending on what Brian has said, a few years back I had a good look at the
hourly output to understand what the heat recovery controls were doing.  I
was using dry bulb controls and ran simulations with a number of
diiferential dry bulb cut-out temperatures.  I found that 6-8DegF was about
optimal for the climate / building I was studying.  The moral of the story
was be careful with dry bulb controls as they will often bring in moisture
and increase loads if you are using a small differential DT.  Conversely
setting a low differential enthalpy control will increase sensible cooling
and on coil temperatures under some conditions ...

Periodically there is a thread on this forum about EQuest's ERVs and heat
recovery and non intuitive results.  My experience has been that if you
understand what the various configuration / control inputs mean then you
will get reasonable hourly and thus annual energy results ...

Regards,
Graham
----- Original Message ----- 
From: "Brian Fountain" <bfountain at greensim.com>
To: <bldg-sim at gard.com>
Sent: Friday, February 03, 2006 3:42 AM
Subject: [bldg-sim] equest recovery


> Note that the default "Make-up air temperature control" for energy
> recovery ventilators in eQUEST is to "Float" the supply air
> temperature -- meaning they will continue to recover heat regardless
> of discharge air temperature, increasing the cooling load unless the
> default is changed.   Changing it to "Mixed Air Reset" has a
> considerable effect -- eliminating most of the excess cooling.
>
> I guess it depends on your economizer operation -- whether it is on a
> fixed drybulb or on differential drybulb or enthalpy.
>
> -----Original Message-----
> From: bldg-sim at gard.com [mailto:bldg-sim at gard.com] On Behalf Of Brian
> Thornton
> Sent: February 2, 2006 11:23 AM
> To: bldg-sim at gard.com
> Subject: [bldg-sim] equest recovery
>
>
>
> One thing I wondered about this was the amount of cooling increase
> showing
> with eQuest modeling of an ERV.  I have not done a real study, but
> tried
> modeling one case without any added fan energy, and running it with
> the
> economizer active with the ERV run control set to WHEN-MIN-OA, which
> turns
> off the heat recovery when the economizer is active (stops the wheel
> for a
> wheel type).  Even with these two strategies, which should eliminate
> the
> bulk of increased cooling, there is still significant increased
> cooling.
>
> Have others tried this, and are there other explanations for the
> cooling
> results?
>
> Brian
>
> Thornton Energy Consulting
> p. 503-231-6600 f. 503-231-3555
> thorntonenergy at comcast.net
>
>
> -----Original Message-----
> From: bldg-sim at gard.com [mailto:bldg-sim at gard.com] On Behalf Of Andy
> Lau
> Sent: Wednesday, February 01, 2006 12:17 PM
> To: bldg-sim at gard.com
> Cc: bldg-sim at gard.com
> Subject: [bldg-sim] equest recovery
>
> Of course one cannot say conclusively what is happening here, but my
> work with heat recovery systems has shown that they often increase
> cooling energy for two reasons:
>
> 1.  They can eliminate the possibility of operating an air-side
> economizer and getting "free-cooling."
> 2.  The fan power associated with heat recovery can be significant,
> which will also increase cooling load.
>
> I attach a paper that was presented at Simbuild 2004 on this subject
> (not attached to bldg-sim because it exceeds allowable size)
>
> Andy Lau, P.E.
> 7group, www.sevengroup.com
>
> fernando varela wrote:
> > Hello:
> >
> > I'm trying a Packaged VAV system with exhaust recovery, and
> > surprisingly, when I add a recuperator, cooling consumption
> increases,
> > instead of reducing!! Can anybody explain this to me?????
> >
> > Thank you.
> >
> > ======================================================
> > You received this e-mail because you are subscribed to the
> > BLDG-SIM at GARD.COM mailing list.  To unsubscribe from this mailing
> list
> > send a blank message to BLDG-SIM-UNSUBSCRIBE at GARD.COM
> >
> >
> >
>
>
> ======================================================
> You received this e-mail because you are subscribed
> to the BLDG-SIM at GARD.COM mailing list.  To unsubscribe
> from this mailing list send a blank message to
> BLDG-SIM-UNSUBSCRIBE at GARD.COM
>
>
> ======================================================
> You received this e-mail because you are subscribed
> to the BLDG-SIM at GARD.COM mailing list.  To unsubscribe
> from this mailing list send a blank message to
> BLDG-SIM-UNSUBSCRIBE at GARD.COM
>
>
> ======================================================
> You received this e-mail because you are subscribed
> to the BLDG-SIM at GARD.COM mailing list.  To unsubscribe
> from this mailing list send a blank message to
> BLDG-SIM-UNSUBSCRIBE at GARD.COM

======================================================
You received this e-mail because you are subscribed 
to the BLDG-SIM at GARD.COM mailing list.  To unsubscribe 
from this mailing list send a blank message to 
BLDG-SIM-UNSUBSCRIBE at GARD.COM



More information about the Bldg-sim mailing list