Loop Operation

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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!



No Username provide's picture
Joined: 2011-09-30
Reputation: 200


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.


Sethi, Amarpreet's picture
Joined: 2011-09-30
Reputation: 0