ReplyThe sewer smell is throwing me off, is it possible something is on the heat strip thats burning, is the duct lined with anything? ie acoustic insulation?
Professional Member
I have a customer complaining of a "sewer" smell coming from the ductwork. The smell only seems to be noticeable when the aux heat strip is on. The air handler is an older Trane unit with 10kw electric heat strip. There doesn't seem to be an odor when only Heat pump is engaged or when the fan is operated, only when the heat strip is on. The exterior of the ductwork seems to be OK when visually inspected. I haven't cut into it yet to check the interior. The odor seems more intense the longer the aux heat is on. Any ideas.
Professional Member
The sewer smell is throwing me off, is it possible something is on the heat strip thats burning, is the duct lined with anything? ie acoustic insulation?
Professional Member
No, just standard ductboard. The heat strip was visually inspected and looks and operates normally. The customer says "sewer" smell, I have been unable to smell it on two previous visits, however, an electrician said it made his eyes water.
Regular Guest
I can't say I have ever heard of a sewer smell with ductboard but during a geothermal install everyone was getting sick prior to and during the removal of all ductboard in the residence as well as a smell that was not mold.
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Professional Member*
Your drain line trap is dry and being in a negative state it is pulling sewer gases.
Professional Member
One of my first thoughts also. But the drain line exits the building through the wall and terminates directly outside., so there is no connection to any type of sewer line.
Professional Member*
Maybe a dead mouse in ducts.
Professional Member*
Change the strips
Professional Member
The mouse makes sense. I'll run a camera through the ductwork to check it out.
Professional Member*
Look up dirty sock syndrome. Sound exactly like what you have.
I've been battling it for years in my climate. It's coming from the evap coil. They make special cleaners. I've had about 50/50 success with those. The best solution is just to change the coil.
The smell comes from a bacteria that grows on the coil and you only smell it when swapping from heat to cool (or defrost).
Professional Member
Makes me wonder if the coil is growing something and only the more intense heat given off by the strips is cooking the nasty that is growing on the coil.
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Most of the time the strips are downstream of the coil.
Professional Member
Heard of it, but never ran into it. I thought it was more prevalent in the humid south, and more commonly associated with high eff. equipment. The unit is about 20 years old, so replacing just the coil is not practical. I just looked at a Youtube video of a guy who claims to have solved the problem with a Pine-Sol solution sprayed on the coil. The aux heat issue has me stumped though, the smell should be most noticeable at initial fan start-up, not after the kick-on of the aux heat strip. If it is the evaporator coil, the smell should also be present in cooling mode. The problem is its about 5*F outside, not a good time to switch to cooling mode.
Professional Member*
It happens to all ages of systems, new and old. It generally happens in the south but I wouldn't rule it out just due to geographical location.
Dirty sock smell happens when swapping from heat to cool. So she says it happens when aux heat is operational - My guess it is happening in defrost which will turn on the aux heat (she sees this displayed) and it shifts into cool momentarily.
When you return, force a defrost and then go sniff around. That's how I duplicate the issue when it's a complaint. I attached a PDF below.
http://wittichen-supply.com/wp-conte...k-Syndrome.pdf
Professional Member*
I've had dirty socks problems myself, might want to check that. I've also had baked snake, mouse, rats etc on strips trying to stay warm.
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I'd be looking for something dead.
Professional Member
True, but most of the time the coil can "see" the strips. Just a thought. I would defintely investigate that coil and pan first.Originally Posted by fliks
Professional Member*
I'd have to agree with Brent. I had one that would smell when it went through defrost, the rest of the time it was fine. Ended up swapping coils with a dipped coil and the issue went away.
Regular Guest
I have had a few dealings with this as well. I know at one point Trane made a special factory "coated" coil to prevent buildup of bacteria. Unfornately this was after a 3k dollar bill from an indoor hygenist.
Professional Member
simple check. If the unit is in a basement. look for a floor drain. Sometimes. the water will evaporate from the trap. The smell will not be noticeable with just fan running. Add the air being heated by the strips you have sewer smell every where,.
Or some one pooped or peeed in the duct work
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