Above ceiling as return plenum
Above ceiling as return plenum
(OP)
Is it normal to use the area above a suspended ceiling as a return plenum? We have a large building with several rooms and zones with no return ducting at all. It seems to me we are picking up a lot of heat in the summer (losing heat in winter). Just curious.





RE: Above ceiling as return plenum
RE: Above ceiling as return plenum
-Wiring in the plenum must be plenum rated (Teflon insulated)
-Partition must not go all the way to the slab above unless transfer air openings are provided
-Transfer air openings must be sized for minimal pressure drop, about maximum 300 FPM velocity to minimize pressurization to effect transfer air flows. Sometimes a transfer fan may be required.
- Maintain fire/smoke rating of rated walls by providing fire or combination fire & smoke dampers where required
- Avoid sound transmission. May have to use transfer air silencers or ducts with elbows & acoustic lining.
RE: Above ceiling as return plenum