[Equest-users] Heatpump ARI conditions - fun with eQUEST curves
Bishop, Bill
bbishop at pathfinder-ea.com
Fri Sep 14 09:23:10 PDT 2018
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<mailto:wbishop at pathfinder-ea.com> www.pathfinder-ea.com<http://www.pathfinder-ea.com/>
[cid:image002.png at 01D44C25.F4845080]134 South Fitzhugh Street
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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nicholas Caton via Equest-users
Sent: Friday, September 14, 2018 11:07 AM
To: equest-users at onebuilding.org
Subject: [Equest-users] Heatpump ARI conditions
Hi everyone,
I've done a little homework/skimming and am coming up dry on a particular question:
Packaged heatpump performance is defined by ARI Standard 210/240 (for units under 65,000 Btu/h cooling) and ARI Standard 240/360 (for larger heatpumps).
Both the previous 2007 and the current 2015 published versions of these standards have two sets of ambient conditions for heating mode, "high temp" and "low temp." Here's a reference from the 2007 copy (I think 2015 has no changes in this regard):
[cid:image009.png at 01D44C21.10F8A770]
Here is an example of the sort of capacity and efficiency stats we can expect to see from a manufacturer (this is a packaged heatpump unit by Trane):
[cid:image010.png at 01D44C21.10F8A770]
The major question here is... which set of conditions (high vs. low) are expected for developing doe2/eQuest gross capacity and HIR inputs? Put another way, are the curves in the library built around one of these specific condition sets? I've always used the higher capacity set (High temp), but when I went to confirm against the doe2 reference entries for these inputs I didn't see anything specified other than "ARI conditions."
~Nick
[cid:image011.png at 01D44C21.10F8A770]
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric
D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com<mailto:nicholas.caton at schneider-electric.com>
15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States
[cid:image012.png at 01D44C21.10F8A770]
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