Water heater vents into the chimney and the furnace no longer does
I Like To Fix
When a chimney-vented furnace is replaced with a high-efficiency PVC-vented unit, the water heater is left venting alone into a flue sized for both. It can fail to draft and spill combustion gases into the house. If you have a CO alarm, test it now. If it sounds, leave the building and call the fire department or your gas utility from outside.
This is most common in homes built before about 1940. Pre-war construction — galvanized supply, cast iron drains, cloth-wrapped wiring, ungrounded circuits.
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
- 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
- Filter slot is a gap behind a grille
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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.