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Central Heat Pump System Working for Cooling But Not Heating

asked 2018-04-05 19:10:36 -0500

chriswmackey gravatar image

updated 2018-04-06 09:49:05 -0500

Hello All,

Now that the newly-released OpenStudio 2.5 seems to have full support for central heat pumps, I have been trying to implement it in some measures and I feel that I am very close to getting it to work. It's completely working in cooling mode and I've successfully connected it to the hot water loop.

However, the heating mode of the heat pump does not ever turn on and there is never any hot water generated. The loop clearly senses the heating demand as the hot water pump ends up pulling infinite electricity. But the temperature of the loop never rises.

I have been racking my brain for the last 4 hours trying to understand why the heating mode of the heat pump is not turning on and I have matched as many inputs as I can with the CentralChillerHeaterSystem_Cooling_Heating.idf example that comes with EnergyPlus.

I thought I would put the question out here in case anyone has encountered this issue. My intuition tell me it's something obvious that I am missing about how tertiary plant loops are supposed to work. Any thoughts or hypotheses are appreciated and, if you are willing to check the issue, you can find a simple single-zone .osm model that recreates the issue here:

https://drive.google.com/open?id=1Ykz...

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You're hitting this issue: https://github.com/NREL/EnergyPlus/is... Not sure that's going to solve your heating issue though. model.getChillerHeaterPerformanceElectricEIRs.each{|comp| comp.setReferenceCoolingModeEvaporatorCapacity(600000)}

Julien Marrec gravatar imageJulien Marrec ( 2018-04-06 10:12:01 -0500 )edit

Thank you Julien! That's exactly what I needed to know. After I hard size the ChillerHeaterPerformance:Electric :EIR, I get the correct heating energy as expected. So, for anyone else experiencing the issue, the solution is to hard size this object instead of letting it autosize.

chriswmackey gravatar imagechriswmackey ( 2018-04-06 13:25:53 -0500 )edit

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answered 2018-04-12 08:22:09 -0500

You're hitting this issue: https://github.com/NREL/EnergyPlus/is.... Not sure that's going to solve your heating issue though, but you should try hardsizing the cooling evaporator capacity:

model.getChillerHeaterPerformanceElectricEIRs.each{|c| c.setReferenceCoolingModeEvaporatorCapacity(600000)}
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Asked: 2018-04-05 19:10:36 -0500

Seen: 69 times

Last updated: Apr 12