I have a stinky smell coming from an air vent in one of my bedrooms. It is no where else in the house, only this one vent. And it only smells at night. But it is a very potent smell. I can't figure it out. This has been going on for about a month. Due to mild weather we have not used the heat or air for two months, so I do not think this is related to a mechanical issue. But I am not sure what to do about it. Any ideas???? Help!

 

guess what it sounds like you got a dead mouse in the flex or other friend id remove the flex going to that vent and look

 

How do I remove the flex? Do I need a professional for this? Any ideas as to why it would only smell at night???

 

A lot is in how the flex was put on. Like by code here the outside cover is sealed to the other duct with mastic. Cut his lose then there should be a band that you have to cut. this will let the cover insulation slide up and there should be another band on the inside liner that you have to cut. Then the flex duct should slide off the metal take off that is in the duct. just put it back the same way.

ED

 

smell at night only hard to say why it could be more moister because it cooler eather way it worth the look and see whats what in there

 

ckc: First I should state my official and professional qualifications for offering advice. I have none. I'm not a moderator or professional handyman. My experience consists of the practical maintenance of my own home plus a couple of rental houses over the past many years.

The foul odor coming from that one floor register (aka "vent,") could be, as has already been pointed out, the result of a decaying mouse or similar rodent in your duct work. One of my tenants had a very similar problem. In her case it turned out that one of her kitty cats urinated in the vent. (Do you have pets?) After a few weeks the odor finally dried up and dissipated.

Duct work is inherently and naturally nasty. All kinds of unsavory stuff will eventually accumulate inside it for you to inhale -- insects, lizzards, mice, lint, dust, mold, mildew, etc. Old duct systems generally have a few leaks or cracks tiny enough to allow insects to get inside. Except for having it replaced (or cleaned) there's not much you can do about it. And no matter what kind of filters you use, dust will eventually build up again inside the ducts.

In one of my rental houses, the contractor replaced the old metal duct system with the new flex duct. I took a look at the old metal duct work after it was removed and I couldn't believe all the junk that had accumulated in it over the years. Gross! Flex duct is cheaper and easier to install -- but because of its corrugated ridges and swirls, it collects more dust and mildew than the now "old fashioned" metal duct work.

With regard to the smelly vent, there is probably less odor at night or when the furnace is not running because the air in the duct system is not being refreshed, hence the stronger, stale odor.

If you have adequate crawl space, you can inspect your duct system for leaks, etc., or have a contractor do it. I don't know about your particular crawl space, but most of them are very tight in places and it's hard to get a close look at all the duct work.

You could also have your duct work professionally cleaned but it's arguable as to whether it really does much good.

Good luck. Just my two cents worth.

 

I don't see anything that says he has "flex" in his post.
Remove the grille, and stick a flashlight and a mirror inside. You might need to cut an access panel into the ductwork if you can't see anything behind the grille. Most likely it's either a mouse or a low point where water collects, which would be a moldy mildew smell.
I respectfully disagree with notsohandy about his views on flex vs. fabricated sheetmetal ductwork. Flex has more resistance to airflow, and is very hard to clean properly. More often than not, it is improperly installed. The main reasons it is being used so much these days is that is is much cheaper and less time consuming to install. It can also be installed by any "semi-skilled" worker, rather than a skilled tin knocker. It is most certainly not "better"
OK--I'm off my soapbox now
Good luck!

 

Take and check it out for sure. Most of the time it dont start till about DECE.I have looked for so many GAS leaks in homes to run it down and find out its methane gas from the drain line on the AC and the trap is dried out and lets the methane gas up and into the home when the drain is not put in to code.

ED My .02 cents