[Bldg-sim] ERV with increasing cooling load

Brian Fountain bfountain at greensim.com
Tue Oct 28 08:28:51 PDT 2008


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.
>     /<MICHAEL.L.KINGSLEY at saic.com>/* wrote:
>
>         From: Kingsley, Michael L. <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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