AHU setpoint managers for simultaneous heating and cooling

mspider · Posts: 47

Hi Team,

I'm using BETA v3.0.0.087 for detailed HVAC simulations. Often we want to model a VAV system without reheat, but instead with heating supplied from a central heating coil in the air handler (example attached).

However, I'm not entirely sure of the best way to ensure that the heating works, i.e. zone temps and PMV indicate that the zones are too cold in winter.

Ultimately, we would like to be able to have a system that alternately switches the cooling and heating coils on and off as required to meet zone setpoints.

Currently we use the SetpointManager:Warmest objects, but these don't really cater for heating - we can't really put the upper limit in the cooling setpoint manager at the heating set point. The SetpointManager:Warmest in EnergyPlus doesn't really cater for heating.

Given the variable climate in Melbourne, Australia, seasonal setpoints don't really work - we can't meet PMV targets etc if we allow only heating or cooling at one time.

We could use multiple setpoint managers on the HVAC demand and supply air loops, but I'm not sure there is a viable option for a single duct VAV system without reheat.

I've attempted to use a SetpointManager:Coldest object in both DesignBuilder and E+ directly along with a SetpointManager:Coldest. DesignBuilder won't allow the creation of the idf file and in E+ I get the message that there are 'no zones with heating found', yet the air handler definitely has a heating coil.

Do you have any suggestions? Could a workaround be to use a dual duct system somehow to model the correct behaviour?

Any assistance is appreciated.

Thanks
Matt

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