Underground ductwork design

[mech711]

Does anybody have any suggestions for underground ductwork materials. What type of material is best. How do you prevent a condensation problem within the ductwork. Are there any useful guidelines for the overall design of the underground system. Any information would be greatly appreciated.

 

[mizzoueng]

FRP, fiberglass reinforced pipe. Works really well, as for the condensation, I've seen people build them with a slope to drain the condensate to a central loctaion. What are you puching through the pipe? Conditioned air or exhaust air? Or outside air?

What is he ambient temp?
Humidity?
Dew Point?
DB/WB?

Or you could just say where you are and those of us with an ASHRAE book could look you up.

 

[mech711]

Pumping through conditioned supply air @ 55 deg db 43 deg wb

the location is new york city

 

[DrRTU]

PCD or fiberglass. Nothing but problems. Slope it to a large drop that a sump pump can be installed. I believe it a big liability for IAQ. Seal every joint and back fill with pea gravel or you will crush the duct. Extend all taps and drops thru the floor with metal tops. All type of construction stuff gets dropped thru open holes. Have a sheetmetal worker onsite the day the floor is poured, the concrete guys move and hit the penetrations. The only systems I like to do are car tailpipe systems and they go in with scd. 40/80 PVC.