Wood to Gas: Three Routes, Costed Including What Your Chimney Needs First
The cheapest conversion is only cheap if your flue passes. Here is what each route actually requires, and why the inspection comes before the appliance decision.
Conversion quotes vary enormously and the reason is usually not the appliance — it is what has to be done to the chimney to support it. Which is why the sequence matters: inspect first, choose second.
01Route one — a log set in the existing firebox
Cheapest appliance, and it needs a gas supply plus a chimney that is sound and open, because it vents up a working flue.
That precondition is where the price moves. If the flue is breached or the crown is failing, those repairs are part of the conversion — and at that point route one may no longer be the cheapest overall.
02Route two — a vented insert
A sealed unit in the existing firebox venting through a liner run up the chimney. Considerably more efficient than a log set because it stops sending room air up the flue, so it changes your running cost as well as the appearance.
It requires a correctly sized listed liner as part of the work, and the unit has to fit the firebox you have. Efficiency gain is the argument; the liner is the cost.
03Route three — full direct-vent
A sealed appliance taking combustion air from outside and venting outside through its own coaxial system, installed to the manufacturer's instructions rather than to the chimney.
This is the route that does not care about the state of your flue at all — which makes it worth pricing whenever the chimney is in poor condition. Sometimes it is genuinely cheaper than relining to support route one or two.
04Why the inspection comes first
A sound flue keeps all three options open and lets budget and efficiency decide. A breached flue effectively removes route one and makes route three worth comparing against the cost of relining.
Choosing the appliance before knowing the flue's condition is how conversions end up costing double what was quoted. All three involve licensed gas work and a leak test — that part is constant.
Get the flue scanned before you choose. The chimney's condition determines which routes are genuinely available, and it is the single input that decides whether the cheap conversion is actually cheap.
Every recommendation here starts from one place: a graded, photographed chimney inspection — and when it's warranted, a chimney relining done to one standard, with a paper trail you keep.
The Prime Chimney Services Team
This article was written and reviewed by the CSIA-certified crew at Prime Chimney Services. Every recommendation reflects NFPA 211 and CSIA trade standards and the same documented, photographed approach we hold every job to.
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