I'm in a condo with neighbors on both sides. utility closet is in the basement.

It smells like old stale cigarette smoke in my utility closet, like somebody has been smoking cigarettes in there for years almost.

I'm not a smoker, and I noticed a faint smell of cigarettes in the past but thought it came from neighbors outside. I've been working from home during the pandemic and realized the smell is definitely coming from the utility closet after following my nose (sniffing all around the house lol) to the source. I don't smell it anywhere else in the house or from any of the ducts. It's just inside of the utility closet really. There's a hot water heater, the air handling fan/heater/evaporator unit, and circuit box in the utility closet.

Also, when I first moved in 2 years ago I never noticed the smell in the utility closet.

I'm not 100% sure, but it almost seems like the smell comes when the heat turns on. Is this possible?

Could the smell come from one of those? or could it be from the neighbors through a hole in the wall somewhere? If it's from a neighbor, how can I find and plug the holes?

  • Hello, and welcome to Home Improvement. Unfortunately, we can't smell your problem from here, so we're unlikely to be able to help you. And, you should probably take our tour so you'll know you'll know the details of contributing here. Apr 1, 2020 at 15:06
  • I vote for outgassing from polyisocyuranate foam, as might be found in water heater or other insulation.
    – kreemoweet
    Mar 9 at 23:25

2 Answers 2


If smell comes when heat turns on, could it be the dust filter? Have you ever replaced the dust filter associated with the fan?

If you have, does the dust filter smell like cigarettes also?

If you have not can you please post an image of dust filter when you take it out? Just for prurient interest.

  • I've replaced the dust filter, and I haven't smelled it from any of the air ducts. I'll post a picture in a bit, it's just a dusty air filter though and it doesn't smell like cigs. In fact I'm not sure it's even tobacco smoke anymore, it just this almost wet salty smokey smell. maybe ive become smell blind to it
    – jreese
    Apr 1, 2020 at 21:27
  • Probably have to "smell" around in there some more. Could it be coming from the panel? Overheating wires? Or wires touching a heat source? Like a hot plumbing pipe or furnace exhaust pipe. Might even be a building material touching the furnace exhaust.
    – user68386
    Apr 1, 2020 at 21:59
  • Filter not smelling like smoke means it is not in the air circuit. Some thoughts: could exhaust be incompletely vented and you smell that? Maybe exhaust is coming into the house? I like the idea of building material in contact with heat - as an explanation, I mean.
    – Willk
    Apr 2, 2020 at 1:17

I'm a couple years late, but if anyone has this issue please look into it ASAP! Sulfur eating bacteria could be present in your water. Look into how old your water heater is and whether it's overdue for replacement. Recommend a new one every decade.

I recently had the same exact issue with my condo's laundry room where the water heater was located. Smelled like something burnt/of cigarettes and over time smelled increasingly bad to the point I had trouble breathing and horrible congestion. Thought it was a flu. My heater was old and once it was replaced, the smell went away.

However if you discover your water heater is less than 10 years old, call a plumber and let them know of suspicious aroma. And they can drain the water, chlorinate the tank to kill off bacteria and see if smell goes away.

Long-term exposure to hydrogen sulfide gas is dangerous to humans and pets. If you can't escape your home immediately, then keep fans on and windows open. Recommend every household to have a gas detector to monitor air levels

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