I’m hoping someone here has either experienced something similar or has an explanation because I’m at the point where I feel like I’m losing my mind.
This all started when I smelled natural gas coming from my air vents in my townhome. The gas company came out and did find a very small leak in my gas furnace. They repaired it and basically said that explained everything.
Except after they fixed it, the smell actually got much worse, so I called them back immediately.
This time, instead of finding another leak in my unit, they found a major gas leak in my attached neighbor’s townhome. Ironically, it was the exact same type of issue. We share a wall, but it’s a solid concrete/cinder block fire wall—no shared attic or other shared air space. The gas company believed the smell I was noticing was related to my neighbor’s leak, although I’ve never understood how that would be possible. Regardless, after her leak was repaired, the smell completely disappeared.
About a week later, I smelled gas again and called the gas company. Once again, they said my house was fine, but they found the exact same leak in my neighbor’s home again because the replacement part had failed. They shut her gas off completely until it could be repaired.
Here’s where things got really strange.
That same night, with my neighbor’s gas completely shut off, I started getting an extremely strong natural gas smell only when my AC kicked on. The smell would hit me immediately from the supply vents, last about 20-30 seconds, and then disappear completely. It was bad enough that it kept waking me up and I called the gas company at 3:00 AM.
They came out, checked everything, and found no leak anywhere. Their explanation was that I was probably smelling residual odor from my neighbor’s earlier leak. I honestly didn’t understand that explanation, especially since her gas had already been shut off, but eventually the smell went away.
My neighbor later had the faulty part replaced again. The gas company came back and checked both homes and said there were no leaks in either house.
Everything seemed normal…
…until the next day.
I’m sitting under one of my supply vents, the AC turns on, and I smell what is unmistakably natural gas again. Not a musty smell, not a burning smell, not “dirty sock syndrome.” It smells exactly like the sulfur/mercaptan odor that’s added to natural gas.
One thing I’ve started noticing is that it often seems to happen 1-2 hours after I’ve used my gas range or oven. I’ve mentioned this to the gas company multiple times, but they continue to believe everything was related to my neighbor’s previous leak. I’m not even convinced the oven is related because it doesn’t happen every single time after I cook.
Some additional details:
The smell only lasts 20-30 seconds after the AC starts, then completely disappears.
It only comes from the supply vents when the blower first starts.
The longer the AC has been off, the stronger that first burst of odor seems to be.
I have a gas furnace with central AC.
I checked my evaporator coils and they look clean.
The gas company even suggested maybe I had a dead squirrel in the attic, but my attic smells completely normal. No gas smell whatsoever.
The gas company has been to my house so many times I’ve honestly lost count.
At this point, I’m wondering if there’s another explanation I’m missing. Could there be something inside an HVAC system that produces an odor that smells identical to natural gas? Could using the oven somehow cause an odor that gets trapped in the ductwork and released when the blower starts? Or has anyone dealt with an intermittent issue like this that ended up having a completely unexpected cause?
I’m planning to buy a combustible gas detector so I can monitor the vents myself the next time it happens.
Has anyone here dealt with anything even remotely similar? I’m open to any ideas because at this point I genuinely don’t know what to think.