Too much ventilation Air

[Golestan]

Hello,
This may be a simple one. I have a 12000 sq-ft white box finish out. It needs to have 2 RTU's @ 15 ton each. Fresh air should be at 25%. Can a baromtric relief damper on the unit compensate for the extra air brought in. Does it depend on the unit construction? Or do I need to relief the air by other means? The bathrooms exhaust 200 cfm.
Regards,

 

[stevenw]

Yes the barometric dampers at the RTU should be able to vent the relief air.
My rule of thumb is 5-10% of the air will be lost thru the construction.
You want to leave 10% of the return air in the space for pressurization.

 

[walkes]

As long as you do not have a long run of ductwork connecting the return air to the RTU you should be ok. (The return penetrates through the roof to an acoustic elbow within the space). If you had a long return run (roof through second floor to main floor) you may require additional relief openings. This would likely only be an issue with the economizer mode on the RTU, up to 100% OA.