[Equest-users] Loop Operation

Sethi, Amarpreet amarpreet.sethi at stantec.com
Sat Nov 21 15:51:20 PST 2009


 
Karen,
 
I've faced the same problem and as a quick fix, I found best to undersize the condenser water loop till the differential was aggreeable, like you said 10F or so, this as you mentioned reduced the pump energy by a quarter. I'm sure there is a more correct way to do this, please share once you figure it out.
 
Regards,
Amarpreet

Stantec

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________________________________

From: Karen Walkerman [mailto:kwalkerman at gmail.com] 
Sent: Friday, November 20, 2009 12:12 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Loop Operation


Hi All,

I'm having some issues with loop and pump operation in eQuest.

I have tested this issue with water loop heat pump loops.  Basically, I set my loop design DT, but for many hours, the loop operates at very low temperature differentials.  With the given load on the loop, this requires a high flow, and results in high pump energy!

Specifically, for a heat pump loop, I'm expecting a 7-10 F difference in supply and return temperatures at all times.  I just ran a test model with a loop design DT specified at 10 F.  For hours when there is a heating only load on the loop, I have an average difference in supply and return temperatures of about 3 degrees.  This requires the pump to move about 3 times more water than necessary.  My system is modeled with variable speed pumps, and isolation valves at each heat pump.

Any suggestions are greatly appreciated!

Thanks,

--
Karen
 
 
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