Blocked HVAC duct

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sligoNoSPAMjoe 17 years ago

I have a HVAC duct that is almost totally blocked. It has been this way since my home was constructed. I suspect a crimped vent or trash in the vent. The problem is the obstruction appears to be a good distance away from either end. I have easy access from the basement and from the second floor outlet. In between those is a long run with several 90º elbows.

I don't want to start tearing up floors and walls to correct the problem. I am looking or suggestions. I was thinking of a camera that could be snaked through the vent. Since I don't know which way some of the turns may be just snaking a standard snake would not likely be really helpful

Suggestions? Sources for a rent a camera?

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Colbyt 17 years ago

Long run, several elbows and if it takes off from the lower pressure side of the plenum might be perfectly normal.

Not all discharge vents have equal air flow.

You might be able to rent a sewer cam from a rental store. I think I saw one in a Harbor Freight ad a while back.

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Kevin Ricks 17 years ago

Are you sure there is not a damper installed in the duct? My system has dampers on all ducts located near the furnace at the main plenum. Look for a small handle sticking out he side of the duct(s).

Kevin

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trader4 17 years ago

I'd try the local tool rental shops for a camera. Or take a look online. There are cheap cameras you can hook to a notebook PC. You might be able to use one of those connected to a snake with a penlight, etc.

If it's a small duct, It's also possible that with multiple 90 turns and a long run, the duct isn't blocked, it just can't carry much air.

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sligoNoSPAMjoe 17 years ago

Yes there is a damper and I have verified that it is fully open.

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sligoNoSPAMjoe 17 years ago

I have considered that, but they all appear to be USB connected and USB does not do will with long cords.

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John Grabowski 17 years ago

*When doing some remodeling on homes, townhouses and condos I occasionally notice that some ducts from the original construction are sometimes a little crushed. However what I find more often is that duct connections are separated. Some of them were just shoved together without screws or foil tape and they came apart for whatever reason. Sometimes in attics I see flex ducts that are flattened from tradespeople and homeowners climbing over them. I have also seen flex ducts that have holes chewed in them from rodents.

Check out plumbing supply companies. You may find one that rents a camera or perhaps they can refer you to a company that does.

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ransley 17 years ago

Is it the longest run with the most elbows, I have one like that. A inline booster blower may help. I have dampers near the furnace that can shut ducts off check your system.

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Bob 17 years ago

I have one that doesn't go anywhere at all. Building inspector must have told the builder to install a cold air return in a hallway. Builder cut out a square of drywall, stuck in a grill, and called it a return.

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trader4 17 years ago

I think USB is specd to work to 15 ft. Which would seem to be long enough, given that you can get at it from both ends. Also, that's the specd limit, I would guess it's fairly likely you could go farther.

ide quoted text -

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makolber 17 years ago

x-no-archive:

return "ducts" are sometimes formed by the space between the 2x4's and sheetrock, no actual ducting is used... Mark

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Bob 17 years ago

I wish that were the case here. It's just an empty cavity bordered by the top plate, the bottom plate, and two studs. Stuck my head in and looked. And, yes, the HVAC performance on that floor is not very good.

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sligoNoSPAMjoe 17 years ago

Good point. I don't know why I did not think if it myself I have seen it more than once.

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Blocked HVAC duct

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