Chemical odor from central heating's chimney

Hi all,

I have an outdoor natural gas central heating unit (which also has a built-in AC). On the side of this large box-like unit is a small vent that outputs hot air/gasses. The odor of these gasses has a VERY strong "chemically" smell. Is this normal, or might there be excessive unburnt natural gas mixing with the normal heater vent exhaust? And can this be dangerous?

Thank you!

-Bill

Answer to furnace vent odor...

To save anyone who may read this thread in the future: the smell from the vent was caused by poisonous gasses due to a cracked combustion chamber in the gas furnace.
There are only two solutions to this problem (that is, if you lived through the carbon monoxide poisoning that this issue causes): replace the combustion chamber (>$1500), or get a new central heating unit (>$4200).
PS: I'm really somewhat surprised that this HVAC forum didn't know the answer to this critical life and death problem...

-Bill

Thanks for posting that.

BTW, this is first and foremost a plumbing forum. HVAC questions that are are more serious than just replacing the thermostat are often given the standard answer, "Call your HVAC professional."

PS: Didn't your CO detector go off, alerting you to a hazardous situation?

If that smell is coming out of the exhaust what would that have to do with a cracked exchanger? If that smell is coming out of the supply ducts then it makes sense.