[bldg-sim] equest recovery

[Mike Tillou]

The equest user manual is a good resource for understanding the use of
ERVs in equest.  A discussion on what the different keywords do and how
to apply them is included in Vol2-Dictionary.  In the Table of Contents
look for "HVAC Components" ---> "System" --> "Ventilation Air".  Scroll
down to the end of this section to find the ERV keywords.

You can find the user manuals on the DOE2.com website

Mike

Michael Tillou, PE
etc Group, Inc.
PO Box 7, Williamstown, MA 01267
ph. (413) 458-9870 fx. (413) 458-9875





-----Original Message-----
From: bldg-sim at gard.com [mailto:bldg-sim at gard.com] On Behalf Of Graham &
Megan
Sent: Thursday, February 02, 2006 3:01 PM
To: bldg-sim at gard.com
Subject: [bldg-sim] equest recovery


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.
> >
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