[Bldg-sim] ERV with increasing cooling load

[Michael Tillou]

 my 2 cents..
 
I can attest first hand to having witnessed ERV systems operating in a
"FLOAT" mode that were using chilled water for cooling on a 50-degree day
because heat recovery increased SAT to ~67F and they then proceeded to cool
SA back down to 55F.
 
I believe equest folks made the ERV default "FLOAT" so that people would at
least stop and think about the fact that an improperly designed ERV system
will actually increase energy use.
 
 
 
Mike
 
Michael Tillou, PE, LEED
Tillou Engineering, LLC
 

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From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Brian Fountain
Sent: Tuesday, October 28, 2008 11:29 AM
To: Xiaobing Liu; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] ERV with increasing cooling load


The eQUEST default for temperature control is FLOAT whereby the heat
recovery device aims to maximize heat recovery for all ambient conditions.
This leads to heat recovery when economizer free cooling would be
preferable.

With "Mixed Air Reset", the device is modulated, either by bypassing air or
by modulating the heat exchanger (slowing the wheel), to maintain the mixed
air temperature at the mixed air temperature setpoint -- which is typically
the supply air temperature setpoint less a couple of degrees for fan
pick-up.  This is definitely a common building automation system strategy.

Xiaobing Liu wrote: 

I'm wondering whether the Mixed Air Reset will really be implemented in the
real system? How big difference the air temperature control strategy will
make?
 
Xiaobing

-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org]On Behalf Of eric wang
Sent: Tuesday, October 28, 2008 10:06 AM
To: bldg-sim at lists.onebuilding.org; Kingsley, Michael L.
Subject: Re: [Bldg-sim] ERV with increasing cooling load



Hi,
 
Thanks a lot for all your replies. I changed the following settings and
solved the problem.
 
Control Sequences Operation: when minimum OA 
Make air temperature cotrol: Mixed Air Reset
 
Best,
 
Shaojie

--- On Tue, 10/28/08, Kingsley, Michael L.
<mailto:MICHAEL.L.KINGSLEY at saic.com> <MICHAEL.L.KINGSLEY at saic.com> wrote:


From: Kingsley, Michael L.  <mailto:MICHAEL.L.KINGSLEY at saic.com>
<MICHAEL.L.KINGSLEY at saic.com>
Subject: RE: [Bldg-sim] ERV with increasing cooling load
To: shaojieworld2006 at yahoo.com, bldg-sim at lists.onebuilding.org
Date: Tuesday, October 28, 2008, 8:09 AM


Shaojie,



Check to make sure that you are not recovering heat during hours that

you can be using the economizer.  Choose the Control Sequences:

Operation: "When Minimum OA" so that the heat recovery device will

only

operate when you cannot benefit from free cooling.



Mike



Michael L. Kingsley, PhD, PE, LEED AP

Senior Engineer/ Project Manager

SAIC

6390 Fly Road

East Syracuse, New York 13057

Phone:  (315) 437-1869  x205

Cell:     (315) 373-4081

Fax:     (315) 437-1866

Email:  kingsleym at saic.com



-----Original Message-----

From: bldg-sim-bounces at lists.onebuilding.org

[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of eric wang

Sent: Monday, October 27, 2008 11:32 PM

To: bldg-sim at lists.onebuilding.org

Subject: [Bldg-sim] ERV with increasing cooling load



Hi,

 

I model a PSZ system with exhaust air heat recovery. I set the static

pressures of supply/exhaust fans as zero in ERV tab. Therefore, the fan

energy is the same with or without ERV. However, there is an increasing

cooling load in the cooling model. I changed the hourly report and

didn't find the reason. Any suggestions are highly appreciated.

 

Thanks

 

Shaojie 



            




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