Hey Nick,
Short answer - high.
Longer answer - These are the default curves in eQUEST for a packaged heat pump:
- PVVT-Heat-EIR-fEDB&OAT
- PVVT-Heat-EIR-fPLR
- PVVT-Heat-CapfEDB&OAT
Using trial and error, and a guess of the rated conditions, you can use the curve coefficients and enter combinations of independent variables (Edb and OAT) to find the corresponding dependent variable (multiplier on hourly EIR or capacity). These curves should give a dependent/output value of 1.0 at the rated conditions. The two EDB&OAT curves give 1.0 output using 70F EDB and 47F OAT.
When creating custom curves, these should always be created in sets based on the same rating conditions. You could create an alternative set of curves that are normalized (give 1.0 output) at 70F EDB and 17F OAT for example. Then you would have to enter the capacity and EIR at the low temperature.
Fun fact - the new beta eQUEST 3.65 build 7174, when run in DOE-2.3 mode, has inputs for temperatures at the rated conditions, and shows the default value temperatures. (The defaults for heat pump heating are 70F EDB, 47F OAT, which I found out after I had already used the trial and error method.) New keywords include RATED-EDB, RATED-EWB, RATED-ECT, and for heating, HT-RATED-EDB, HT-RATED-ECT. The hourly simulation takes these alternative rating condition values into account.
Happy Friday,
~Bill
William Bishop, PE, BEMP, BEAP, CEM, LEED AP
Senior Energy Engineer
[Pathfinder-EA-logo-2]T: (585) 698-1956 F: (585) 325-6005
bbishop at pathfinder-ea.com
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