Crawlspace Ducting Question For The Pros

ctbuilder

Hi everyone -

I have a 4 foot crawlspace.

I have one HVAC company that wants to branch off the metal main trunk with metal, insulated branches and the other company wants to branch off the trunk with flexible, plastic covered insulated duct.

Any thoughts would be appreciated. My thought would be rodents eating thru soft, insulated, plastic covered duct.

Thanks in advance

MechanicalDVR

Metal duct has less resistance to flow than flex any day , that and many other facts make a sheetmetal branch superior to flex.

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thom

Yeh, what he said.

A.D. Const

And last longer.

troubleseeker

Just another support for their answers. The metal duct , with properly sealed joints and properly insulated is a far superior application.

And that applies no matter what the location IMO.

Diesel65

Unfortunately if they want to they will eat through the insulation on the sheetmetal aswell, however all that will happen is the duct will sweat and you will lose some efficiency.

If you put flex in there they will penetrate the duct and end up in your house or even die in there,(that's not very nice).

SHEETMETAL is the only way to go, just make sure that the contractor makes good joints at the grills and uses mastic on all the joints, even the Snaplock or Pittsburg seam.

aldematt57

Good advice from everyone here on this one.
Round sheet metal duct, as noted, has the best aspect ratio of all other materials used to convey air.
If you have an enclosed crawl, you might also want to consider a nice under house dehumidifier to keep humidity levels down.
The upfront costs are high for the dehumidifier and the labor costs are higher for sheet metal duct, but they will pay dividends if you go that route.

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