[Bldg-sim] 2 Pipe System Heating/Cooling Change Over

[James Hansen]

I usually use a snap function to specify when the loop is in heating /
cooling:

 

 

 

By the way, I've modeled a few 2-pipe systems (in the DC area) before,
and it is nearly impossible to get the unmet load hours below 300 for
the average building (without significantly relaxing the thermostat
setpoints, or having supplemental heating/cooling systems).  Hopefully
you are not modeling this for LEED purposes!

 

GHT Limited
James Hansen, P.E., LEED AP
Senior Associate
1010 N. Glebe Road, Suite 200
Arlington, VA  22201-4749
703-243-1200 (office)

703-338-5754 (cell)
703-276-1376 (fax)

www.ghtltd.com <http://www.ghtltd.com/> 

 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Justin Chin
Sent: Monday, March 18, 2013 5:06 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] 2 Pipe System Heating/Cooling Change Over

 

Hello eQuesters,

 

  I am trying to model a two pipe system with a demand operation loop
for a residential building in Maryland.  Currently, my two pipe system
turns on cooling when the zones are calling for cooling as expected,
however it never changes over to heating during the winter.  It is
always either off, or on very rare occasions cooling, resulting in high
unmet heating hours.  Can some one explain how the two pipe system
determines when to change from heating to cooling mode?  

 

I've looked at the zones they are definitely below the heating
throttling range.  Does eQuest take a sum of the room loads on the loop
to determine to heat or to cool?

 

Your help is greatly appreciated.


Thanks!
Justin

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