Use an outside air loop with no conditioning with ZoneHVAC components
My actual building has water-cooled heat pumps cooling and heating each individual spaces, and there are several rooftop mounted supply air fans that supply 100% OA with no conditioning whatsoever, all load is handled at the space level.
I'm trying to use:
- Zone HVAC equipment for each zone:
ZoneHVAC:WaterToAirHeatPump
. I've set the outdoor air flow rates (cooling, heating, no load) to 0 on this - An AirLoopHVAC with nothing but an outside air system, a supply fan, and serving each zone through an AirTerminal:SingleDuctUncontrolled object. That will allow me to model the actual fan power consumption, and any DCV strategy I want to try.
I want the ZoneHVAC equipment to size correctly with the unconditioned outside air being brought in by the AirLoopHVAC.
I've tried to set the zone sizing objects as follow:
Yes, !- Account for Dedicated Outdoor Air System
ColdSupplyAir, !- Dedicated Outdoor Air System Control Strategy
33.2, !- Dedicated Outdoor Air Low Setpoint Temperature for Design {C}
8.7; !- Dedicated Outdoor Air High Setpoint Temperature for Design {C}
Where 33.2 is my summer design day dry bulb and 8.7 is my winter design day dry bulb.
This is because I read in the I/O Reference:
ColdSupplyAir means that the ventilation air will be used to supply cooling to the zone. Cold outside air is heated to the upper setpoint; warm outside air is cooled to the lower setpoint. A good choice for the setpoints would be 12.2 and 14.4 degrees C.
Problem is, I'm getting the following severe errors:
** Severe ** Sizing:Zone="XXXX", invalid data.
** ~~~ ** ... Dedicated Outside Air Low Setpoint for Design must be less than the High Setpoint
What am I missing?
(If you see a better way to model this situation, let me know)
I am just curious why you created an HVACAirLoop rather than just using the natural ventilation object with a fan, That might have made the sizing easier to deal with.
Because why not right?! :)
Like I said mostly because this allows me to model closer to reality (my design specifies the fan characteristics and pressure drop and i can try dcv and have the fan laws correctly represented). And then it's a matter or having one airloop with multiple zones or one ventilation object per zone... I prefer the former.