Why does my more-efficient GSHP have lower tank temperatures?

asked 2017-11-07 02:37:59 -0500

updated 2017-11-07 05:20:54 -0500

The image below shows two model runs, both with a 2.5 kW GSHP. The 2014 one has a CoP of 2.14 and the 2040 one a CoP of 2.41. Other than that the systems are identical. The only other difference between the runs is that the external temperatures have been increased in the 2040 EPW.

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The power (labelled energy) seems right, but for some reason the water tank temperatures are consistently lower in the run with the higher CoP and external temperatures.

What could I check to try and figure out the root cause of this difference?

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Are the two heat Pump system sizes identical - or both autosized? The higher ambient air temperatures may lead to reduced Heat Pump has less capacity - or at least a different response from the same Heat Pump object.

TomB's avatar TomB  ( 2017-11-08 05:16:38 -0500 )edit

@TomB some of the fields are autosized. But how does the ambient air temperature affect the GSHP?

Jamie Bull's avatar Jamie Bull  ( 2017-11-08 06:37:28 -0500 )edit