Re: [EnergyPlus_Support] Control Zone air Temp of radiant hydronic cooling panels in Energyplus

The radiant system has it's own thermostat setpoint that it tries to maintain. Because of the "throttling range" (see documentation), set the setpoint so that it is "stricter" than that of the air system (usually 1 Kelvin stricter than the air system setpoint, with a throttling range of 1 Kelvin, i.e. +/- 0.5 K is sufficient).

To try and control the heat transfer, instead of the zone temperature (which can also use operative thermostats, if nessessary), you would need to use an EMS to change the supply water temperature (or mass flowrate), but from memory, I don't think this will work because of how the solver and the code execute...however, I'm not sure anymore.

2017-02-10 2:05 GMT+01:00 am.kntu.1990@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:

Â

Hello Guys,

I actually modeled hydronic radiant cooling panel using ZoneHVAC: Low temperatureRadiant: ConstantFlow and also VariableFlow in a thermal zone. In both cases, it is actually possible to define set point for the water side and both radiant systems can calculate the sensible cooling rate, panel surface temperature, etc for the conditioned space very well. However, now I want to control the water mass flow rate of the hydronic radiant system using the zone air thermostat controller, so that I have certain heat transfer value between the radiant cooling panel and zone air but I could not manage to do this in energy plus. For radiant cooling system, when I defined ZoneControl: Thermostat to control zone air temperature (as for example to cooling setpoint=24 C), but the results shows that I could not manage to achieve 24 C as zone air temperature. As I checked some forums, I figured out that (ZoneControl: Thermostat) is actually defined for forced convection systems not radiant panels, so then I tried to define an air system parallel to the radiant hydronic system for the zone and this time defined (ZoneControl: Thermostat), so that it could control zone air temperature but I found out that (ZoneControl: Thermostat) only controls air system and actually kick out radiant cooling panel from the whole simulation process (meaning that the radiant sensible cooling rate=0 and in fact the air system took charge of all zone load compensation).Â So far, does any one know what might be the problem? How can I control the working status of radiant cooling panel (such as radiant panel's heat transfer, water mass flow rate, etc.) using zone air thermostat set point, so that I get constant air temperature (as cooling setpoint) in the zone?

Looking forward to hearing from your comments,
Thanks
Ardi
Â