[Equest-users] WSHP Heating Capacity and Allocation of Boiler Load

[Stellberger, Charles]

Hello All,

 

I'm a novice eQuest user in the process of trying to learn some of the
ins and outs of the program.  Your questions and answers have already
helped me immensely over the last couple of weeks, but I wasn't able to
find an answer to my latest question in the archives, so here goes
nothing:

 

I'm attempting to find overall percent energy savings associated with
using more efficient water-source heat pumps.  Keeping all other aspects
of my model unchanged, I raised the heat pumps' cooling and heating EIRs
to represent a drop in both EER and COP_h (to observe the increase in
electricity use associated with that one action).  Total energy increase
was less than I expected because the boiler attached to the water loop
ended up using less natural gas to heat the loop; I remember reading
that this is because eQuest uses the ratio of COPs to calculate WSHP
compressor capacity, meaning that I'm actually increasing WSHP heating
capacity by lowering the ratio of COPs.

 

Ideally, I'd like to keep WSHP capacity constant and use the changing
efficiency to make the units consume more electricity.  I've tried both
hard-inputting zone capacities under the Air-Side HVAC section as well
as using the Heat Sizing Ratio; neither strategy resulted in constant
natural gas use.

 

My hourly reports seem to indicate that the boiler is allocated less
load whenever I lower the heat pumps' COPs.  Does anybody know how I
might be able to keep  load allocation constant between runs?  Overall,
I'd like the WSHPs to deliver the same amount of heat regardless of
efficiency, but use more electricity in doing so.

 

Thank you very much!

 

Charles Stellberger
Energy Engineer 

 

274 Summer Street | Boston, MA 02210

			
T 617.574.8169 | F 617.423.7401 

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

			

 

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