Hi All,
I am trying to model a building which has a minimum fresh air AHU serving all zones, each of which also has a local cooling unit. I was trying to model this using a single zone AHU for each zone, with outside air to all units coming from the multizone unit, which I created later, however I am getting an error saying that the multizone AHU needs to be assigned at least one zone. How can I do this, when all of the zones are assigned to a local unit? If I assign a small zone to get rid of the error, will the multizone AHU only be sized for the cooling load associated with this zone? How can I confirm that the multizone AHU is sized for the appropriate fresh air load?
Regards,
Andrew
Andrew,
Create a Dummy space, very small 1ft x 1ft x 1ft with no load and then a
Dummy Zone for it and use this for your zone. I would not use Multi Zone but
rather PSZ if you are supply the fresh air at a constant volume or PVAVS if
it is supplied at a variable volume.
Best,
Carol
Hi Guys,
May I ask why are you doing this process?
My understanding is that I double click on each zone, go to the Air flow/Outside Air, and enter the CFM of the fresh outside air. In what cases do I need to create an AHU for fresh air?
Thanks!
Omar Katanani
Hi Omar,
If the heat reclaim is on a separate central air handler, with the cooling duty for each space on a local unit this avoids duplicating heat reclaim plant, reduces fan work by only circulating most of the cooling air locally, and allows each of the local units to be controlled separately to respond to variations in load (VAV vs Cooling terminals + min. fresh air).
Regards, Andrew