Duct/Furnace Concern

Archive Public Archive
1

Originally Posted By: Steven Smith
This post was automatically imported from our archived forum.


I was asked to cut some vents in the wood near the corners of a house that is having problems with Wood Destroying Organisms. Generally this went fine. But I have discovered something that, frankly, I am not sure just what it is.


CRAWL SPACE ISSUE:

On one side of the crawlspace, for the full run of a furnace duct, someone has nailed a piece of tin under the farthest most floor joists. They have run a round furnace duct, which does hook to the furnace (which is barely out of the crawlspace in an attached basement) under this tin. Then, just in from the corner..where I put a vent...they have the furnace duct cut up into the piece of tin. It is like a 'tin chamber" with a single duct going into it

I cannot figure out what this is ???? The tin is just tacked below these two joists. Looking into the chamber, to the sides are the joists, above is wood floor boards.

If it is a cold air return, it is sucking in, and recirculating, air from a very unhealthy environment: Musty odor, with Anabiid Beetle, carpenter ant, termite frass, and excessive moisture, no vapor barrier adding to the smell and bad biology. With my new vent hole there, fresher, but colder, air would be getting in, I guess.

If it is for hot air, then it is a weird one because the duct, where it cuts through the tin chamber does not ever go up into the floor of the house. It would dump the hot air only into the "tin chamber."

It was my luck, as it is nearly impossible to get in the crawlspace, that I happened to place my vent hole exactly at the end of this "tin chamber." No tin was cut, but a wood piece was removed at the end of it, so the vent hole opens this odd tin chamber to the outdoors.

I am not sure what to do here? (1) forget about the vent at this location and carefully patch the hole; (2) Call in a furnace professional to figure out what in the world is going on; (3) leave the vent where I put it.

Anyone with experience, who can give me any advise on what this appears to be would be of help. It's because I have not yet been able to get in the room for, or run the furnace, that I do not know if it is a hot air or cold air duct.

The furnace is probably about 25 years old and runs on oil.

Thanks for any suggestions.

SS

2

Originally Posted By: James D Mosier
This post was automatically imported from our archived forum.


I’m thinking your neither a Home Inspector nor a HVAC guy. (This isn’t a put-down) I would choose #1, forget about the vent at this location and carefully patch the hole. Then I’d inform the owner about the strange ductwork and advise them to have a HVAC guy check it out due to the unhealthy environment the ductwork resides in.


Maybe a call to the local health dept (from the owner) would be in order to assess that environment.

--
Jim Mosier

3

Originally Posted By: Steven Smith
This post was automatically imported from our archived forum.


James,


Thanks. I am intending on taking the home inspector course in a month, but have not at this time. For the past few years I have been involved in a number of hom projects, for myself and others.

I am thinking based on your post that, maybe I should have the ducts looked at while the hole is still there, as it does provide a pretty good view of the whole arrangement, in spite of the constricted crawl space.

SS

4

Originally Posted By: jpeck
This post was automatically imported from our archived forum.


Sounds like it was a stud space, or joist space, duct.


When you cut the end off it, you cut open the duct.

Your patch needs to be made with extraordinary care and effort as the wood patch not only needs to be able to keep out the weather, but also needs to be done in such a way as to reseal the duct. I'd have an a/c person reseal the duct, then make the wood repair. This way, the duct is sealed indecently of the wood repair, and if it leaks, that is the a/c persons fault, not yours.

Why is this critical? Because that is blowing, i.e. supply air (or sucking, i.e., return air) air into or from the stud or joist areas, which could cause condensation problems (if blowing) or problems with contamination of the air in the house (if sucking).

--
Jerry Peck
South Florida