Ductwork and Condensation
Ductwork and Condensation
(OP)
Does anyone have any experience in utilising bare ductwork (i.e. uninsulated) when supplying conditioned air. I have seen systems installed without it, but I am concerned that condensation will occur.
Are there any simple guidelines or any documentation that indicates what the limitations are.
My scenario is a large glazed car show room (10m high glass by 60m long) and I will be supplying about 6m3/sec of air at about 13 to 14C.
The room will typically be at 22 to 23C (no specific humidity control,(i.e. only heating or only cooling)).
I know that I can estimate (from the room conditions) that the dew point for the air in the space will be 11C for 22C/50% and the supply air will be 13C so theoretically the risk of condensation at these conditions is zilch, but if the room temp rises to 24 and the % hum is 60% then the dew point is 15.7C and so theoretically condensation will occur.
I suppose I have answered the theory side, but what about the practical side. i.e. would it really cause a problem? How often would it happen?, are there any simple mods to the controls I could make to reduce the risk? (possibly raise the supply temp if the hum level goes too high etc etc?
Any comments
Cheers
Are there any simple guidelines or any documentation that indicates what the limitations are.
My scenario is a large glazed car show room (10m high glass by 60m long) and I will be supplying about 6m3/sec of air at about 13 to 14C.
The room will typically be at 22 to 23C (no specific humidity control,(i.e. only heating or only cooling)).
I know that I can estimate (from the room conditions) that the dew point for the air in the space will be 11C for 22C/50% and the supply air will be 13C so theoretically the risk of condensation at these conditions is zilch, but if the room temp rises to 24 and the % hum is 60% then the dew point is 15.7C and so theoretically condensation will occur.
I suppose I have answered the theory side, but what about the practical side. i.e. would it really cause a problem? How often would it happen?, are there any simple mods to the controls I could make to reduce the risk? (possibly raise the supply temp if the hum level goes too high etc etc?
Any comments
Cheers
Friar Tuck of Sherwood





RE: Ductwork and Condensation
I have done and seen many installations where supply air duct is a bare uninsulated one and the return air is collected freely and returned back to the AHU room without ducting.
HVAC68
RE: Ductwork and Condensation
TOK
RE: Ductwork and Condensation
If I insulate the exposed ductwork, I think it would look yucky, unless there is a nice insulated finish anyone can recommend..or perhaps I could paint the insulation.
It would be better if the ductwork is left bare as it would look better and be more cost effective.
Friar Tuck of Sherwood
RE: Ductwork and Condensation
I have never seen any with condensate problems and many newer restaurants are going this route with open ceilings.
RE: Ductwork and Condensation
RE: Ductwork and Condensation
HVAC68
RE: Ductwork and Condensation
There shouldn't be any problem unless there is some stratification and this is negligible if you have low return. The reason for painting the duct in bright colors may be to increase the emittance of the ducting and thus minimizing condensation.
Regards,
RE: Ductwork and Condensation
RE: Ductwork and Condensation
For instance, you can run uninsulated supply AC ductwork through conditioned spaces, not close to radiant surfaces like hot roofs, where warm air will gather. Do not run uninsualted ductwork though spaces where the difference in temperature between inside adn outside dcutwork air is quite diffrent, for instance AC ductwork through unconditioned spaces like attics.
RE: Ductwork and Condensation