Plenum Pressure

[PokerGuy62]

A client we serve asked this question below. Not really our area and not sure of the answer. Assuming "yes" but don't really know for sure. They are using ducted return obviously.

"Do you know if the ceiling in OR is a positive plenum ceiling?"

 

[e hilton]

Wouldn’t a plenum ceiling be negative pressure?

 

[Paul Sweet]

I think the OR itself has to be under a slight positive pressure, and the space above the ceiling would also have to be the same, unless it had a hard impermeable ceiling.

 

[PokerGuy62]

I think the OR itself has to be under a slight positive pressure, and the space above the ceiling would also have to be the same, unless it had a hard impermeable ceiling.

The OR is required to be at least .01"wc positive. They are not drop ceilings, but hard with access panels.

 

[TheCommish]

Is the interstitial space above the ceiling being used as a return air plenum? Or is there ducted return air? If the space is being used as return air I could see it being slightly negative.

 

[e hilton]

The OR is required to be at least .01"wc positive. They are not drop ceilings, but hard with access panels.

Looks like you are answering your own question …

 

[Genduct]

A client we serve asked this question below. Not really our area and not sure of the answer. Assuming "yes" but don't really know for sure. They are using ducted return obviously.

"Do you know if the ceiling in OR is a positive plenum ceiling?"

With "Eggcrate "Grills" I suspect the negative pressure is so low as to be difficult to measure the pressure diff