[Equest-users] VRF Heating COP in eQUEST

[Bishop, Bill]

Hi Fred,
For VRF condensing units in eQUEST, the heating EIR is a function of other variables. You can use the following keyword expression to determine the heating EIR that is used by eQUEST. It can be entered as a user input expression into one of the other keywords, so you can see how it changes when you change the other variables. (For example, you can enter it as an expression for MIN-UNLOAD-RATIO or MIN-HGB-RATIO, which have default values that are close to the heating EIR, in case you leave the expression in when you simulate.) You can see all the variables that determine the heating EIR in the expression:

/* This expression will calculate the heating EIR that DOE-2.3 will use
   for a VRF condensing unit. You can input this as a user expression
   in another keyword such as MIN-UNLOAD-RATIO. */

#L("COOLING-EIR")*(#LR("EIR-FSST&SDT","COEFFICIENTS",0)
+#LR("EIR-FSST&SDT","COEFFICIENTS",1)*#L("HEAT-RATED-SST")
+#LR("EIR-FSST&SDT","COEFFICIENTS",2)*#L("HEAT-RATED-SST")**2
+#LR("EIR-FSST&SDT","COEFFICIENTS",3)*#L("HEAT-RATED-SDT")
+#LR("EIR-FSST&SDT","COEFFICIENTS",4)*#L("HEAT-RATED-SDT")**2
+#LR("EIR-FSST&SDT","COEFFICIENTS",5)*#L("HEAT-RATED-SST")
*#L("HEAT-RATED-SDT"))
/(#LR("EIR-FSST&SDT","COEFFICIENTS",0)
+#LR("EIR-FSST&SDT","COEFFICIENTS",1)*#L("COOL-RATED-SST")
+#LR("EIR-FSST&SDT","COEFFICIENTS",2)*#L("COOL-RATED-SST")**2
+#LR("EIR-FSST&SDT","COEFFICIENTS",3)*#L("COOL-RATED-SDT")
+#LR("EIR-FSST&SDT","COEFFICIENTS",4)*#L("COOL-RATED-SDT")**2
+#LR("EIR-FSST&SDT","COEFFICIENTS",5)*#L("COOL-RATED-SST")
*#L("COOL-RATED-SDT"))

Remember that fan energy should be accounted for when converting rated EER or COP to EIR. Doug Maddox shows how to calculate VRF EIR in this presentation:
http://maddoxenergy.com/eQuest_DOE23_VRF.pdf
Cooling EIR for the condensing unit: (3.413/AHRI_EER-0.01138)/(1+0.01138)
I believe you would reverse the fan energy for heating. Heating EIR = (1/COP+0.01138)/(1-0.01138)
The constant 0.01138 is the allowance for indoor fan EIR.
Also, I created a modified BDLDialogs.txt file to use with DOE2.3. The file adds these keyword capabilities to the eQUEST interface:

  *   SYSTEM:RATED-FLOW
  *   SYSTEM:HRATED-FLOW
  *   SYSTEM:NUM-COOL-STAGES (for PVVT systems)
  *   SYSTEM:NUM-HEAT-STAGES (for PVVT systems)
  *   SYSTEM:LOW-FAN-PWR (for PVVT systems)
  *   SYSTEM:MAX-CAP/UNIT (for VRF coils)
  *   CONDENSING-UNIT:TYP-CAP/SYSTEM (for VRF condensing units)
The file also adjusts the number of decimal places displayed for several keywords, such as the cooling EIR that you mentioned. I am happy to share this file with eQUEST users (it is ~1.7 MB).
Regards,
~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/>
134 South Fitzhugh Street
Rochester, NY 14608               [cid:image007.png at 01D51B76.269AD5B0]         Ask me why Carbon Fee & Dividend may be right for you.

From: Equest-users <equest-users-bounces at lists.onebuilding.org> On Behalf Of Porter, Frederick NOR via Equest-users
Sent: Tuesday, June 4, 2019 7:22 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] VRF Heating COP in eQUEST

So, in the VRF interface I can enter Cooling EIR, but Heating EIR is calculated somehow from other inputs:

[cid:image008.png at 01D51B76.269AD5B0]

The 0.3 above is actually 0.29, reflected below. But how best to get the heating EIR to 0.30, instead of 0.34? I was thinking of changing some of these "Heating Rated" temperatures. But I'd like to know if someone else has done this successfully.

[cid:image009.png at 01D51B76.269AD5B0]

Fred

Fred Porter, LEED(c) AP
Principal Engineer
Sustainability Services
NORESCO

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