Cooling with dedicated OA

5 posts / 0 new
Last post

Is there a way to create a cooling system using only Outside Air? I have tried to set the cooling coil to 0% and I have also tried to use the dedicated OA options. There is a “ventilation only” system but it is only for heating…

 

We often have this type of system here in northern Canada, mostly for industrial building, where cooling coil and condensing unit are not required. Outside temperature is always lower then the set point.

 

Thanks,

 

Yohan

 

yohan's picture
Offline
Joined: 2013-01-10
Reputation: 0

Yohan, 

If the system  consist of 100% outdoor air in summer, than you can choose the "Dry bulb" for the economizer, Go to 

1) Create system 

2) Options tab 

3) select Dry bulb for economizer. 

Any one can Correct me if i am wrong or have any other opinion. 

Thank you 

Anil Bhari

anilbhari1's picture
Offline
Joined: 2011-11-14
Reputation: -1

Well, what you could simply do is ignore DOA altogether. Then, at the room level, set the ventilation to 100% supply air (for heating and cooling). You could set the cfm of supply air if you want to get really specific, though this could cause unmet hours. You would have to keep this consistent for all rooms on a system.

Alternatively, you could go to create systems, options tab, advanced options and set the ventilation override to 100% OA. 

In this case, it is not a good idea to use DOA, because you only have one air handler.Thus, just focus on making your existing system operate at 100% outdoor air.

Joe's picture
Joe
Offline
eQUEST User
Joined: 1969-12-31
Reputation: 400

Exactly Joe, this is what yohan might looking for. Joe do you have any comment regarding the economizer. As yohan mentioned that outside temperature is always coolder, cant we set up Dry buld for economizer, so that the system will take outside air all the time.

Thank you 

Anil Bhari

anilbhari1's picture
Offline
Joined: 2011-11-14
Reputation: -1

I think the economizer method would work exactly as needed, but only for the specified climate where the OA temp is ALWAYS cooler than return air.

It should be noted that either approach would get the job done, and if you combined both of them, it would be redundant, but would still get the job done.

(though in this particular case, it wouldn't make sense to use the overrides button).

Just make sure that you aren't over-ventilating in heating mode (the economizer method takes this into account automatically, or if you are specifying cfm and 100% outside air, make sure to do so in cooling only (unless for some odd reason you have 100% outside air in heating mode).

Joe's picture
Joe
Offline
eQUEST User
Joined: 1969-12-31
Reputation: 400