[Equest-users] Simultaneous Heating & Cooling

Paul Diglio paul.diglio at sbcglobal.net
Wed Feb 4 10:30:10 PST 2015

Nick & John:

Thanks for the feedback.

This is an apartment building with 41 apartments.  I modeled a PTHP for each apartment.  Each apartment has 2 zones, the living area, bedroom and toilet are one zone and the kitchen is another since I had to add a kitchen hood to this zone.  Ventilation air is only about 35 CFM per apartment and is supplied by an ERV.  The ERV return serves as a toilet exhaust.

So the ERV supplies 35 CFM of ventilation air and exhausts 35 CFM out the toilet.

The ERV does not have any supplemental heating or cooling.

The apartment in the hourly results I sent has one exterior wall facing North.  I added another apartment to the hourly results with one exterior wall facing South.  The South apartment actually uses less cooling during the winter.  I also commissioned this project and the South facing apartments were very warm on a 10 degree day if the sun was out and the blinds up without the heat pump running.  Very confusing.

I changed the throttling range to 2 then 4 degrees and this did not help.

Any other ideas?

Paul Diglio

87 Fairmont Avenue
New Haven, CT  06513

 From: Nicholas Caton <ncaton at catonenergy.com>
To: John Aulbach <jra_sac at yahoo.com>; Paul Diglio <paul.diglio at sbcglobal.net>; EQUEST Users List <equest-users at lists.onebuilding.org> 
Sent: Wednesday, February 4, 2015 11:54 AM
Subject: RE: [Equest-users] Simultaneous Heating & Cooling

Hi Paul,
The combination of tight throttling range inputs and close heating/cooling setpoints can contribute to a single system swinging between heating and cooling each hour.  Something to consider.
That said, I would presume & verify from your observations that you have multiple zones assigned to this zonal system type (a separate system is modeled for each zone assigned).  If that’s the case, then likely some zones are calling for cooling while others are calling for heating during the winter months (classic perimeter/core situation).  
Do you have contextual reasons to believe all zones should be in heating at every hour (i.e. no substantial differences in exterior exposure or interior loads)?  
On another hand, do you mean to model a single set of heating/cooling coils for a group of zones?  In that case you may want to switch to a non-zonal system.
Hope that helps,
Caton Energy Consulting
  1150 N. 192nd St., #4-202
  Shoreline, WA 98133
  office:  785.410.3317

From:Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of John Aulbach
Sent: Wednesday, February 04, 2015 7:59 AM
To: Paul Diglio; EQUEST Users List
Subject: Re: [Equest-users] Simultaneous Heating & Cooling
Paul, is that throttling range 3 or 0.3? A tight throttling range makes eQuest do flip flops on cooling and heating. Have you tried a larger throttling range?
I assume this is representing a single PTHP unit. Is it possible that eQuest is cooling part of the hour and heating the other?
This is certainly an interesting problem.
John R. Aulbach, PE
On Tuesday, February 3, 2015 2:11 PM, Paul Diglio <paul.diglio at sbcglobal.net> wrote:
Hi Folks:

I have modeled some PTHP with variable speed compressors.

I am getting simultaneous heating and cooling during the winter months.  See attached spreadsheet.

I have not specified humidity control and the throttling range is .3.  The heat set point is 72 and the cool set point is 75.

Any ideas?

Thank you,
Paul Diglio

87 Fairmont Avenue
New Haven, CT 06513

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