A same-position combi swap is a one-day job — water and gas off in the morning, heating and hot water back the same evening. Fitted prices start at £1,999 and include the boiler, flue, wireless thermostat, magnetic filter and a system cleanse, with the manufacturer warranty registered in your name.
The quickest route to a new boiler
A like-for-like swap is quick because almost everything in your heating system stays put. The radiators stay. The pipework largely stays. The boiler's position on the wall stays, which means the gas run, the water connections and usually the flue route are already where they need to be. The only major thing that changes is the box on the wall — and the filter, thermostat and fresh chemicals that come with it.
That is what separates a swap from a conversion or a boiler move: no cylinder to strip out, no tanks to drain down in the loft, no new pipe runs through the house. Less work means less disruption, less making good, and the lowest prices on our list.
What stays, what changes
Stays: your radiators, your existing pipework (the survey confirms it is up to the new boiler's output), and the boiler's position on the wall.
Changes: the boiler itself, the flue (every new boiler gets its own), the room control — upgraded to a wireless thermostat — and a magnetic filter added to protect the new heat exchanger. The water in the system changes too: flushed through, chemically cleaned and dosed with long-term inhibitor, which is a condition of the manufacturer warranty. The full itemised inclusion list is on our installation process page; every line of it applies to a swap.
How the day runs
Water and gas go off in the morning — that is the only real disruption, so fill the kettle first. The old boiler comes off the wall and the new one goes on. Pipework is adapted where it needs to be, the filter goes in, and the system is flushed through, cleaned and dosed. Later in the day the boiler is fired, the radiators are balanced and the flue is checked. Everything is back on by the evening: we set the controls, walk you through the thermostat, register the warranty and leave the paperwork.
You do not need to prepare much beyond clearing access to the boiler and, if you can, to the radiators. We bring everything else and take the old boiler and packaging away with us.
Swap prices
| Job | Warranty | Fitted price |
|---|---|---|
| Baxi / Main Eco Compact — combi swap | 5 yr | £1,999 |
| Worcester Greenstar 1000 — combi swap | 5 yr | £1,999 |
| Baxi 600 — combi swap | 7 yr | £2,199 |
| Worcester Greenstar 4000 — combi swap | 10 yr | £2,699 |
| Vaillant ecoTEC plus — combi swap | 10 yr | £2,699 |
| Worcester Greenstar 8000 — combi swap | 10 yr | £2,899 |
| Conversion to combi (from system or open vent) | — | from £2,699 |
Every price includes the boiler, horizontal flue, wireless thermostat, magnetic filter, system cleanse and inhibitor, Building Regulations notification, and removal of the old boiler. Same-position swaps. Estimates confirmed after a free survey.
What can slow a one-day job
Most swaps finish in a day, and the survey is where we catch the things that can stretch it or add cost: a gas supply pipe undersized for the new boiler's output, a flue that has to be re-routed, a fused spur that needs moving, a system so heavily sludged it needs a power flush before the warranty is valid, or condensate that has to be run to a soil stack. We would rather flag any of these at the survey than surprise you on the day — the written quote covers them before you commit.