I live in a townhouse and I hired a company to remove the smoke odor in the house. Now, the odor is almost gone when the heat is off.

However, every time I turn on the heat, the smoke odor will come back. The company I hired says the odor comes from my neighbor. They tell me that, because there is smoke smell in my neighbor's house (which is true) and our ventilation systems are connected (which I am not sure), the odor will be sucked into the vents and then get into my house when I turn on the heat.

But my furnace is a closet in my living room, and my neighbor's heat is NOT on when I turn on my heat. That's why I'm not sure if the ventilation systems are connected.

So I wonder if there is a way to tell if my ventilation system is connected to my neighbor's.

Also, if it's connected, how to fix it? If it's not connected, what could be the cause of the odor when the heat is on?

Thank you very much!

  • What type of heating system do you have? Have you changed the filter(s) (if applicable)?
    – Tester101
    Dec 5, 2016 at 18:46
  • @Tester101 It's a central heating system. And yes, I have changed the filter, and I'm using a so-called odor reduction filter from 3M/Filtrete, but it doesn't work well.
    – chaohuang
    Dec 5, 2016 at 18:56
  • Do you mean cigarette smoke? That smell is REALLY hard to eradicate. And yes, it's absolutely in your ducts. It would have to be. Dec 6, 2016 at 1:58
  • @Harper yes, it's the cigarette smoke.
    – chaohuang
    Dec 6, 2016 at 18:57

2 Answers 2


I'm not sure about the codes in your local, but to my knowledge it's not legal in my area for townhouses to share anything. With that in mind, your smell is most likely residual in your ducting. Even if your cleaner did a very good job cleaning it, there's probably still some soot hiding somewhere.

If you have an actual furnace (gas, oil or electric) you could also have something hiding in the furnace that's being burnt. Inspect there when you have it manually shut off and see what's happening. If you're system uses a heat pump the. Noting should be getting hot enough to cause that. If it is has the gas pressures checked cause that could become dangerous.


I'd bet that the smoke odor has permeated the dust coating the inside of your ducts. Until you have them cleaned well it'll remain.

Be aware that duct cleaning services have a spotty reputation. I had mine done years ago, and a few months later I opened the system for a basement remodel. I vacuumed out mats of dust as large as hand towels from all up and down the main trunk line. Unless you can get a good visual inspection, my confidence is low that most companies will leave you with truly clean ducts.

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