Relief / make up air for PRV’s

Ok, this is might seem like some pretty basic stuff, but I’m coming from residential and recently took a job at a university where I’m responsible for 28 buildings ranging from single family houses all the way up to a community center with two large gyms and a multi-use pool.


I’m wondering how relief / make-up air is typically provided to offset powered roof ventilators. In one dorm, we have two 2,250 PRV’s that run 24/7/365. The only source of relief OA is through 3 small air handlers and one larger one with OA dampers. Even if these dampers were wide open and everything was running at 100% efficiency, they still couldn’t provide even half of the OA required to make up for what is being exhausted.


There’s no other source of OA to provide relief anywhere.


Doesn’t there need to be relief provided into the spaces served by the exhaust? What I mean is one of the PRV’s serves 4 bathrooms. Underneath the doors is the only source of make-up air (and through every nook and cranny, of course).


How would relief OA typically be provided? Is our problem simply too much exhaust and the current air handles should be enough or is there something missing altogether?


We have 3 dorms with this issue that were all remodeled 7 years ago.


Should the PRV’s be dialed down and the OA dampers on the AHU’s be at 100% whenever they’re running? Is that how it’s usually done? Currently the OA dampers are set at 10 or 20% minimum and only open fully when economizing.


The buildings have some massive negative pressure issues, so I know there’s an issue, but I don’t know what a normal system would be in this situation.


If you made it through my ramblings, thanks! Hope it made a little sense.

Relief / make up air for PRV’s

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s