Homeowner decision guide
Furnace repair or replace: put safety and venting first
A furnace decision may involve an ordinary component failure or a potential gas, combustion, or carbon-monoxide hazard. If a professional reports a safety concern, pause the price comparison and obtain the appropriate qualified assessment. Otherwise, compare the written repair with a complete installed replacement scope.
Put combustion and venting ahead of price
- Ask what test identified the failed part and whether the repair would address the cause rather than only the symptom.
- Check whether the furnace or its components are covered by a manufacturer or installer warranty; record only confirmed coverage.
- A replacement bid should address venting, combustion testing, duct connections, gas and electrical work, and permits, not just the furnace cabinet.
Furnace scope on the proposal
A missing cell means the quote has not said. Ask whether that work is excluded or will be priced later. Do not treat a blank as included.
| Written item | On a repair quote | On a replacement quote |
|---|---|---|
| Heat exchanger, gas, or CO | Written finding, or a stop until a qualified test exists | Not a reason to shop price while a hazard is open |
| Venting | Whether the repair restores the existing vent | New vent material, route, and who connects it |
| Combustion check | The test that identified the failed part | Startup combustion test included in the total |
| Ducts and gas piping | Left alone unless the quote adds them | Connections included or listed as extra |
- Equipment model and capacity with sizing basis
- Venting, gas, electrical, and duct connections
- Permit, combustion tests, removal, disposal, and labor warranty
Questions for the furnace contractor
- Is there any documented gas, venting, heat-exchanger, or carbon-monoxide concern?
- What diagnostic test supports replacing the whole furnace instead of repairing the part?
- Which venting or duct changes are included in the total?
Compare the repair only after safety is clear
A safety or venting concern stops the price comparison. Enter the repair quote even if the replacement price is still blank, and keep each proposal's rebate on its own line.
Use the free worksheetWhat a furnace worksheet cannot decide
The worksheet never decides whether a furnace is safe. A possible hazard overrides its financial output. Age and past repairs add context but do not become a made-up failure probability.
Sources
- ENERGY STAR: when to consider replacing heating and cooling equipment
- FTC: comparing written home-improvement estimates
Reviewed October 9, 2026. Program eligibility and local requirements should be confirmed before approving work.