[harum]

I was wondering if anyone had a similar experience with a pungent smell spread by the heating system. This morning I felt a strong unpleasant smell right after the heating/ventilation started the morning heating cycle to the point that I felt nauseous. The smell is everywhere where the ventilation has outlets, and the strongest in the basement area around and next to the heater. It reminds me mostly of a skunk - it's as foul-smelling and meaty, not chemical. But I also suspect tar from the roof or some burned plastic/isolation somewhere in the electric system. I have had this smell before, once in a while, over the last year, one or two days at a time, not so strong though. What I noticed is that the smell apears when the heater is not in use for a day or two (and I have to use it all year around pretty much here in North California), which happens on rare sunny days. I have not used the heater yesterday and before this morning, as it was bright sunny all day. This is why I suspect roof tar, which may become roasted by the sun and stinky fumes can somehow be sucked into the ventilation (even though I don't see where they come close and why it shows up in the morning). We have also had rats in the house, so it is possible that one got jerkied somewhere in hot air ducts (or many, as it is a recurring problem). But again, I only feel this smell ~ 10 times a year, sometimes stonger, sometimes just a hint. I would appreciate it if anyone could share thoughts on this. h.

[hvac1000]

Smells can be the hardest thing to track down. Sometimes a thing called air inversion can happen under the right circumstances.

Inversion (meteorology) - Wikipedia, the free encyclopedia

USATODAY.com

Many times the smell form the sewer that normally goes out the vent pipe on the roof will fall to the ground area instead of going upward and mixing with fresh air and thus disipating the smell. When this happens people complain of smell they never had before or that the smell is only there a few time per year. This could be your problem.

Now the only other way to check is by a visual check of everything in the home including possible defective toilet wax ring gaskets that seal the sewer vapors from the house that can come from where the toilet mounts to the floor. The smell can be from anywhere.

[dobiefloyd]

Sounds like or I mean smells like rats to me. Now how are they getting in there?

[dobiefloyd]

Floor drain? Is this a 90% furnace. I have seen rusted cast traps that will drain in a days time. If it not producing condensation for a day the trap might be draing.

[wmproop]

it's as foul-smelling and meaty,



could it be a dead bird= foul=meaty,

pun intended,, shame on you wmproop

[harum]

Thanks. It's nothing like toilet smell, or rotten food, or garbage. We have skunks around and accidentally the smell is just like them, with a hint of tar and burned rubber to me. Air inversion is a possibility I guess.

[KC13]

While this may offer no help, it seems like a relevant story. A few years ago, I was called out for a similar complaint (foul odor when heating operated for first time that season). The system was a central forced-air furnace located in a basement, with split a/c. The source? A pet snake had "disappeared" over the summer. I found it, dead, on the a-coil. It apparently found its way into a floor register and down the plenum. The cold a-coil must have retarded "spoilage", as the homeowners said they didn't notice any odor over the summer. Needless to say, the decomposed and half-roasted carcass wasn't a pretty sight - or a pleasant aroma!