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ZoneHVAC: LowTemperatureRadiant: ConstantFlow

asked 2021-03-18 05:36:05 -0500

Soares's avatar

updated 2021-03-22 08:23:42 -0500

Hello I'm working with ZoneHVAC:LowTemperatureRadiant:ConstantFlow, I have doubts about the meaning of the Zone Radiant HVAC Heating Rate output variable, if it really symbolizes the heat supplied to the environment, because the delta T of the inlet and outlet water changes, but the rate variation is small. A larger T delta should result in a higher rate. Any suggestion?

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Julien Marrec's avatar Julien Marrec  ( 2021-03-18 08:13:14 -0500 )edit

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answered 2021-03-18 08:29:05 -0500

The I/O reference guide for the output variable Zone Radiant HVAC Heating Rate [W] states:

This field reports the heating input rate to the low temperature radiant system in Watts. This is the heat source to the surface that is defined as the radiant system. The heating rate is determined by the zone conditions and the control scheme defined in the user input.

So yes. If you are only looking at inlet&outlet temperatures and the Zone Radiant HVAC Heating Rate, you should also at least look at the Mass flow rate in the system as well to gain some rough interpretation of what is going on.

More info: Source code / Engineering reference:

The source code that sets the Output variable in question is located here in

HeatPower maps to totalRadSysPower which is the sum, for each surface of state.dataHeatBalFanSys->QRadSysSource which is calculated in ConstantFlowRadiantSystemData::calculateLowTemperatureRadiantSystemComponents and described in the Engineering Reference in chapter Radiant System Models

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Asked: 2021-03-18 05:36:05 -0500

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Last updated: Mar 18 '21