Cost Guide
Warm Air Heating Replacement Cost Guide (2026)
If your warm air heating unit is coming to the end of its life, you have more options than most heating firms will tell you — and ripping everything out for radiators is rarely the cheapest one. As one of the UK’s few Johnson & Starley warm air specialists, here’s an honest guide to what each route typically costs.
Your three options when a warm air unit fails
Most general heating engineers only quote one option: strip out the ducting and install a boiler with radiators. A warm air specialist can usually offer three, and two of them keep the fast warm-up and radiator-free rooms you bought the system for.
- Like-for-like modern replacement — a new Johnson & Starley WarmCair condensing unit in place of your old Economaire or similar. Up to 98% thermal efficiency and over 28% fuel savings vs old non-condensing models.
- Aquair hybrid upgrade — keep your existing ducting, but drive it from a modern heat source (combi boiler, heat pump or electric boiler) via a Heat Interface Unit. The greenest path, and it future-proofs the house.
- Full conversion to a boiler and radiators — the biggest job: new pipework throughout, making good the redundant ducting, and losing warm air’s fast heat-up.
Typical costs in 2026
Exact pricing depends on the unit, flue arrangements, ducting condition and whether domestic hot water is involved. As honest ballparks for a typical 3-bed home:
- Modern WarmCair replacement: typically in the £5,750–£10,120 range installed, depending on model and hot water configuration.
- Aquair hybrid upgrade: usually less than a full replacement where ducting is sound — priced per survey.
- Conversion to boiler + radiators: commonly £7,000+ once pipework, radiators and making-good are counted — and often quoted higher by firms who simply don’t want warm air work.
- Annual warm air service (keep your existing unit healthy): a fraction of any of the above — see our service contracts.
Why so few engineers will quote for warm air
Warm air heating needs a specific Gas Safe qualification (Domestic Warm Air) that most engineers never take — the installed base is concentrated in 1960s–80s housing stock and only one UK manufacturer still makes the units. The result: owners get told "we don’t touch those" or receive inflated rip-it-all-out quotes.
Plumbusters services, repairs and replaces warm air systems every week across Kent, London and the South East, and we’re proud to be recommended by Johnson & Starley themselves.
Frequently Asked Questions
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