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Re: [EnergyPlus_Support] Self Contained VAV with a Variable Speed Water-to-Air Heat Pump



I don't think Unitary Units accept you to put a setpoint on any nodes, meaning you can set them, but they have no effect. The fan is an integral part of the unit and is controlled by the unit. I don't think that you can limit the air delivery temperature. You can set a air delivery temperature at design conditions in the sizing:zone object, bit that is just used to size the unit's coil and fan. After that the unit will do all in it's power to meet the load.

I am unaware of setpoint control for this object, but there has been a lot of developement on it of late.

Mit freundlichen GrüÃ?en- Sent from my iPhone (excuse the brevity)

i. A.
Jean Marais
b.i.g. bechtold
Tel.   +49 30 6706662-23

On 12.05.2015, at 22:56, "noahpflaum@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

 

Has anyone been successful or tried to use the Coil:Cooling:WaterToAirHeatPump:VariableSpeedEquationFit component on an AirLoopHVAC:UnitarySystem as a way of modeling a self-contained VAV with a variable speed compressor? I have used the OpenStudio API to set up a self-contained VAV with the unitary system and a Coil:Cooling:WaterToAirHeatPump:EquationFit component, which works fine, and I also used the setString method to set the control type to SetPoint rather than load based (sorry!). No problems here. However, when I changed the heat pump out with the variable speed component then no load was seen on the unitary system and the compressor didn't turn on. The EnergyPlus example file that has the variable speed heat pump on a unitary system uses a load control type on a zone so I tried adjusting my IDF and got the error below. It is wanting me to use a Fan:OnOff object, but this defeats the purpose of the VAV if I have to do this.

* Severe * AirLoopHVAC:UnitarySystem = AIR LOOP HVAC UNITARY SYSTEM 1 * ~~~ * Supply Fan Object Type = * ~~~ * Fan type must be Fan:OnOff when Supply Air Fan Operating Mode Schedule Name = Blank. * Fatal * GetUnitarySystemInput: Errors found in input. Program terminates.

Since then, I have placed my fan in my unitary system and used the load control type and specified a control zone and this seems to be working. However, when I adjust it's control type back to SetPoint I have the same issue I started with in that I can't get my heat pump to turn on at all. If anyone has encountered this before, or if they have any advice, it'd be much appreciated.




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Posted by: "jeannieboef@xxxxxxxxx" <jeannieboef@xxxxxxxxx>


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