ceiling return
ceiling return
(OP)
is it advisable to have ceiling return at the roof with insulation? Because I imagine it also have heat load.
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RE: ceiling return
RE: ceiling return
RE: ceiling return
RE: ceiling return
In thermal load calculations, additional outside heating/cooling load has to be taken into account, and that is about it.
RE: ceiling return
RE: ceiling return
RE: ceiling return
RE: ceiling return
Do what MechEngNCPE says, he's on the money.
Good on ya,
Goober Dave
RE: ceiling return
(load calculation will cover the space from the floor to the roof not to the false ceiling)
- return plenum has no separate load than building load, it is a part of building load calculation, it effects on load distribution between zone level and coil level.
- example: let say we have a zon in building has a roof load of 50000 Btu/hr.
- in case of return duct, all this 50000 btu/hr is a zone load which determin the cfm required for this zon.
- in case of return plenum, a part of this 50000 Btu/hr will go directly to the unit's coil and the rest will go into the zone.
- in both cases the coil load is the same but the zone load is different.
RE: ceiling return
If you run two calcs in Trace or HAP with and without RA pleneum, you will see a different air flow for the zone as indicated by 317069 - the RA plenum requires less CFM for each zone/space than the ducted return. substantially less - as nuch as 30% I've seen.
In cold climates, it is a good idea to have RA plenum to keep pipes in the plenum from freezing.
the thing to watch for is a conversion of a RA plenum system into a Ducted system. Something not to do.
RE: ceiling return