Rust or soot streaks at the furnace heat exchanger
I Like To Fix
A cracked heat exchanger can put carbon monoxide into the supply air. Do not run the furnace. If anyone in the house has headaches or nausea that improve when they leave, treat it as an emergency – get everyone outside and call 911 or your gas utility from outside the building. Have the exchanger inspected before the system runs again.
This is most common in homes built roughly 1940 to 1980. Post-war and mid-century — copper supply, aging cast iron stacks, 60 to 100 amp panels, first-generation central air.
Safety — no contractor call. Follow the instruction above. The correct call here is the utility, 911, or a doctor, and putting a contractor number on this page would be indefensible.
Related
- Ductwork threaded through a house built for floor grates
- One central return for the whole house
- Water heater vents into the chimney and the furnace no longer does
- Silver-wrapped tape on old duct joints
- Additions still on window units
- Uninsulated walls and an oversized condenser
- Furnace runs but the house never warms evenly
- Electrical panel cannot support a modern condenser
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Written by Jaylan Jones. I Like To Fix earns a referral fee when a call connects to a contractor. See our business-model disclosure.