Difference of cooling capacity between cooling coil total cooling rate + fan and VRF heat pump total cooling rate

asked 2018-10-01 22:06:51 -0600

Alexis
545 ●1 ●10

updated 2018-10-02 19:46:57 -0600

I am trying to do a simple simulation to understand the link between all the output in Energy plus. I have used a HVAC templates system / zone VRF. No ventilation. No sizing factor. One thermal zone.
When I check the output, I have a difference of cooling capacity (in W) between : cooling coil total cooling rate + fan electric power is different than VRF heat pump total cooling rate.
I have : 16802.43 + 119.89 is not equal to 17763.99.
I have tried many simulations by changing some parameters but I always have a difference. Its not a lot but I would like to understand before extending my model.
What did I forget ? Or what is the reason of this difference ?
Thank for your help

answered 2018-10-03 08:14:35 -0600

rraustad

13804 ●79 ●12 http://www.fsec.ucf.edu/

Without seeing your input file the other influence I can think of at the moment is piping losses (see report variable: VRF Heat Pump Indoor Unit Piping Correction for Cooling). However 5% does seem large so if this doesn't resolve the difference then update the numbers and I'll check again.

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I dont have this report variable. I checked and double checked in my rdd file. Nothing about piping loss.
But it seems to be that because when I set the lenght and the height at 1 m, my cooling coil total cooling rate + fan electric power + piping loss is almost equal to VRF heat pump total cooling rate.
I am using E+ v8.7, perhaps this output is arrived after this version ?

Alexis ( 2018-10-03 20:22:01 -0600 )edit

The piping correction report is only for AirConditioner:VariableRefrigerantFlow:FluidTemperatureControl. At least you now know why there is a difference in the reports. Good job on figuring that out.