Has anyone had problems with modelling zones that are conditioned by relief air? Is this a problem that is in the developers 'to-do' list?
Basically, I have a building with 2 CAV systems with air economisers in which the fan room is conditioned with relief air from both AHUs. Does anyone know of a simple way to connect this room so that it is conditioned by this air? Is there a way that you can connect both relief air nodes (or even just one) to the zone?
Currently the workarounds that I'm thinking of are:
1) Put the room in the return air stream as a return air plenum. However, this would mean that the return air that gets to the economiser would be significantly cooler/warmer depending on the room conditions which is not acceptable.
2) Create a separate purchased air system that supplies air to the fan room with maximum heating and cooling flow rates that are the same as the total combined flow from the AHUs. The problem with this is that the heating and cooling supply air temperatures are fixed, and cannot be varied with a schedule. Thus, I will have to use a supply air temperature that is the average of the return air temperature to the AHUs.
Hopefully someone has a better idea as neither of these are ideal! -- Regards, Paul
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