[bldg-sim] equest recovery

Gerald Pde geraldpde at yahoo.com
Thu Feb 2 11:22:58 PST 2006


The reason why your cooling load goes up because if
the ERV control is set where the fans run throughout
the HVAC operations, the ERV recoveres heat in summer
where the cooling coils need to then recool. One way
to mitigate this is to add a bypass damper for the OA
coltrol so that when the building is economizing, it
bypasses the ERV. Set minimum OA and mixed air reset,
and choose OA bypass. Also in heat recovery 2, you can
set the supply fan to "self contained" instead of the
fan energy being picked up by the HVAC main equipment.

Hope this helps.
Gerald

--- Brian Thornton <thorntonenergy at comcast.net> wrote:

> 
> 
> 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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