Strange Duct in Crawl Space

[Joe Funderburk, CMI]

Anyone know what the purpose of this is? From inside the crawl space, I found this duct attached to a flex duct that goes up through the floor. The duct has a wire screen in it to keep out rodents.

Here's my guess. The structure was a double-wide mobile home. It had a pre-fab metal fireplace with metal chimney. The duct was under the area of the fireplace. I think it is to provide combustion air to a tightly built structure. Do you agree?

If that's what it is, when the HVAC is on, will it not suck in air from the crawl space???

[jmichalski]

Any more info available on what is directly over this duct?

[NWJon]

Originally Posted by jfunderburk

Anyone know what the purpose of this is? From inside the crawl space, I found this duct attached to a flex duct that goes up through the floor. The duct has a wire screen in it to keep out rodents.

Here's my guess. The structure was a double-wide mobile home. It had a pre-fab metal fireplace with metal chimney. The duct was under the area of the fireplace. I think it is to provide combustion air to a tightly built structure. Do you agree?

If that's what it is, when the HVAC is on, will it not suck in air from the crawl space???

If it is to the fireplace it would most likely be the "outside" combustion air intake.... and no... when the HVAC kicks on.. it shouldn't suck air in.. at least not in any different manner than any other pre-fab fireplace with outside air intake ducting.

Cheers, Jon

[lwillick]

It could also be sending heat into a crawl space. This is quite common here where it is so cold. And this type of duct is connected to the furnace duct heat out put vents.

Hope this helps.
Regards,
larry