[Equest-users] WSHP question

[Ana N.]

Hello e-quest users,
 
I am working in detailed mode and need to change from PTAC to WSHP (a cooling tower provides cold water and condensing boiler provides hot water to WSHP). I calculated EIR from EER and COP using the equation that was recommended for packaged VAV on this forum.  Is there a more accurate way of calculating EIR for heat pumps? I also noticed that my energy cost increases when I use higher COP (electricity consumption decreases but natural gas consumptions goes up significantly, more that I would expect).   SV-A report shows that e-quest auto selects heat pumps of larger capacity if I enter larger COP. I also have significant increase in the energy cost if I manually increase the heating size of WSHP while keeping EER and COP unchanged. Since my HP cycle I would not expect significant increse in cost with larger HP at the same heating load. Am I wrong?
 
I would greatly appreciate if anyone would share his/her experience with modeling WSHP. Why would cost increase with higher COP and do you have e-quest auto size WSHP?
 
Thanks
 
Ana Nedeljkovic
 
HVAC Engineer 		 	   		  
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