[Equest-users] Simultaneous Heating & Cooling

Nicholas Caton ncaton at catonenergy.com
Wed Feb 4 08:54:15 PST 2015


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,



~Nick



*NICK CATON, P.E.*
*Owner*



*Caton Energy Consulting*
  1150 N. 192nd St., #4-202

  Shoreline, WA 98133
  office:  785.410.3317

www.catonenergy.com



*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
203-415-0082


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