Orphaned chimney after electrification

Avoid leaving a water heater or remaining appliance on a chimney that became oversized after a furnace/boiler was removed.

VERT / GREEN

Inventory every appliance connected to each vent before conversion.

JAUNE / YELLOW

Removing a large appliance can change draft, flue-gas temperature and condensation in the remaining chimney.

ROUGE / RED

Remaining combustion appliance on altered common vent, condensation signs or spillage: qualified heating/gas professional before operation.

Interactive triage

Helps choose the next step; it does not replace design, permits or professional diagnosis.

Furnace removed, gas water heater remains
Re-evaluate vent sizing; liner or different venting may be required. Wet/powdery chimney signs
Inspect condensation, masonry and liner. All appliances becoming electric
Plan safe decommissioning of vent and penetrations. Venting inventory current
Keep photos and served-appliance list.

Useful tools and data

Appliance/vent inventory
Chimney/liner photos
Nameplates

What the professional checks

Re-evaluate venting
Test draft/combustion
Inspect condensation/liner

Official sources

Checked 2026-08-22.

RNCan — guide chauffe-eau

Related path

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