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Waterheater:HeatPump COP

asked 2018-03-08 16:29:52 -0600

Lindsey Gaunt's avatar

updated 2018-03-09 12:17:08 -0600

Hi there,

I couldn't find a post about this so I thought I'd start one.

For the Waterheater:HeatPump object in Openstudio, why can't you choose an efficiency higher than 1? Is this a bug?

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@lgaunt3 please state exact variable you are talking about. Are you referring to the Heater thermal efficiency?

Avi's avatar Avi  ( 2018-03-09 04:34:33 -0600 )edit

Yes the Heater Thermal Efficiency

Lindsey Gaunt's avatar Lindsey Gaunt  ( 2018-03-09 10:12:21 -0600 )edit

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answered 2018-03-09 14:18:15 -0600

Avi's avatar

You probably want to read here in the Input Output reference about the WaterHeater:HeatPump:PumpedCondenser which is what I assume OS uses when you call for Waterheater:HeatPump object.

You see, OS is creating in the background few different E+ object in order to fulfil your demand. Evident for that can be seen when you select the component in the Thermal Zone tab and look at the Edit tab on the right.

If you roll down you will see the different OS object created. One of them is OS:WaterHeater:Mixed the one where Heater Thermal Efficiency is.

So that refers to the secondary heat source of the water tank in this configuration after the first source which happens to be the OS:Coil:WaterHeating:AirToWaterHeatPump.

Since the tank heater is not a Heat Pump it's efficiency can go as high as 1. If you don't need the tank heater which is default to run on Natural Gas you can hard size it to 0 W.

If you roll further down you will find the OS:Coil:WaterHeating:AirToWaterHeatPump object where you can change the coils COP or even further down the efficiency curves.

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Asked: 2018-03-08 16:29:08 -0600

Seen: 244 times

Last updated: Mar 09 '18