How can I get the right output report for reversible air-to-water heat pump?

asked 2017-11-07 20:10:15 -0500

Hi unmethours community !

Thanks for reading my question. I'm still a beginner with Energyplus, and I need some help here ! :)

I'm modeling an air source heat pump that supplies for a hydronic radiant floor, with heating and cooling modes, and I'm having some troubles getting the output report right.

For heating operation I used WaterHeater:HeatPump:PumpedCondenser & Coil:WaterHeating:AirToWaterHeatPump:Pumped objects with a mixed water heater, and for cooling operation I used an air-sourced Chiller:Electric:EIR. image description

For the output variables, I'm not exactly sure which ones to use to correctly describe the operation.


It seems to me that the condenser object only has parasitic electric powers and energy as outputs. The water heating coil is considered as a cooling coil by energyplus (it cools outdoor air), so I'm using the outputs "Cooling Coil :Total water heating rate & energy, and cooling coil : water heating electric power & energy" > Is it correct?

When I get the report tables, I can't find the water heating outputs, they are signaled as [Invalid/undefined]. So I used monthly report of output variables (water heating total energy & electric energy). Problem is, it doesnt match with the EnergyConsumption Report. The electricity used for "Water systems" is slighty higher than the water heating total electric energy from the output variables (1640 kWh/year against 1445). Any idea why? What is missing ? (It's not the evaporator fan, it's referenced as 'fans:electricity' and is exactly as expected.)


For cooling, i use the variables "Chiller : evaporator cooling rate/energy, Electric Power/energy, COP". Everything seems pretty consistent between variables & table outputs. I just don't get why the evaporator cooling rate at full operation is fixed and can't be higher than the rated value as it is for heating. Besides that, the COP match with the cooling rate/electric power only when the chiller is on for the full hour, as for heating. Should I just use cooling energy/electric energy then?

I've got one last question, even if it has nothing to do with whats above.

I'd like to model ceiling fans in cooling mode to help with destratification. Changing the room air model seems rather complicated, so I wanted to directly change the convection coefficient for the floor surface. Problem is, to calculate it I need the air velocity around the floor. Any idea how I could get an average value of that, if the fan & room characteristics are known? Or any idea to do otherwise to model the presence of a ceiling fan would be welcomed as well !

Thank you so much for reading this, I hope you will be able to provide some help :)

Cheers !


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