It’s usually the first thing people ask us, normally after the old boiler has had one breakdown too many. Across the UK, a straightforward combi swap typically costs somewhere between £1,800 and £4,000 fitted, and that’s a fair guide for homes in Bristol and Bath too. Where you land in that range depends on the type of boiler, whether it’s staying in the same spot and what state the rest of your heating is in. You can see what’s involved in our boiler installations, but here’s how the price actually breaks down.
What you should be getting for your money
The boiler is only part of the bill. A proper quote should also cover a new flue, taking away the old boiler, cleaning the system, a magnetic filter to catch sludge before it reaches the new boiler, and the controls.
It should also include any pipework changes, notifying Building Control and registering the guarantee with the manufacturer. If you’ve got three quotes and one is a lot cheaper, look at what’s missing from it. It’s nearly always one of those.
The controls aren’t optional either. In England, the Boiler Plus rules say every new gas boiler needs time and temperature controls. A new combi also needs one extra energy-saving measure on top, such as weather or load compensation, a smart thermostat with automation and optimisation, or flue gas heat recovery.
What pushes the price up or down
Combi, system or regular
A combi heats your hot water as you use it, with no tank and no cylinder. For most flats and houses with one bathroom it’s the simplest and cheapest to fit, which is why a combi boiler installation is the job we quote for most.
System boilers run with a hot water cylinder. They’re a better fit if you’ve got two bathrooms and people showering at the same time in the morning. Regular boilers have a cylinder plus a cold water tank in the loft, and you’ll still find plenty in older houses.
Swapping like for like keeps the cost down. Changing from a regular system to a combi means taking out the tanks and cylinder and reworking the pipes, and that’s extra time. Nationally, a conversion typically costs around £3,000 to £5,000, sometimes more.
Moving it
Leaving the boiler where it is will always be cheapest. Moving it from the kitchen into the loft or a utility room means running new gas, water and condensate pipes, plus a new flue route. It’s often worth doing. It’s just not free.
The flue and condensate
Every new gas boiler is a condensing boiler, which means a condensate pipe taking slightly acidic water to a drain. A flue that has to go up through a roof, or a long run to get the condensate to a drain, adds labour.
Size
Bigger houses with more radiators need more output, and higher output boilers cost more. Oversizing just wastes money, so we size it at the survey, not off a guess over the phone.
The state of the system
If your radiators are full of black sludge, it’ll shorten the life of the new boiler. Sometimes a heavier clean is needed before we fit anything.
Worcester Bosch prices
Worcester Bosch sits at the top end of the market. The Greenstar 2000 is their entry model, the Greenstar 8000 is the premium range, and price goes up with output and if you need a system or regular version. Nationally, a fitted Worcester Bosch combi typically costs from around £2,000 for a Greenstar 2000 on a simple swap to £4,000 or more for a Greenstar 8000 or a conversion.
A good chunk of what you’re paying for is the guarantee. As Worcester Bosch accredited installers, we can offer up to 12 years on selected models, as long as the boiler is serviced every year.
What we see in homes around Bristol and Bath
Housing stock makes a real difference. Plenty of terraced houses in south and east Bristol have a combi on the kitchen wall with the flue going straight out the back. Swapping one of those is usually a one-day job with no surprises.
Bigger Victorian and Georgian houses in Clifton, Redland and across Bath are more likely to have an old regular boiler, a cylinder in the airing cupboard and tanks in the loft. Converting those, or upgrading to a system boiler with a decent cylinder, is a bigger job.
Then there are back boilers. You’ll still find them behind gas fires in a lot of 1960s and 70s homes, and taking one out is a different job again from a straight swap. If you’re in a listed building, speak to the council before we move a flue, because changes to the outside can need consent.
Spreading the cost
You don’t have to find it all at once. We offer interest-free and longer-term finance through Novuna Personal Finance, subject to status and a credit check. We act as a credit broker, not a lender. The representative examples and who’s eligible are on our boiler finance page.
Should you replace it before it packs up?
If you can, yes. You choose the date, you get time to compare quotes, and you’re not shivering while you wait for a slot in January.
If your boiler’s past 12 to 15 years, keeps needing callouts or parts are getting hard to come by, get a price now. A straight swap usually takes a day. A conversion or a move can take two or three.
Frequently asked questions
Is a combi cheaper to fit than a system boiler?
On a like-for-like swap, usually, because there’s no cylinder. But if you’re converting from a system or regular boiler to a combi, the extra pipework can wipe out that saving. And if two of you shower at the same time every morning, a combi might not keep up anyway.
Will a new boiler cut my gas bill?
If you’re replacing an old non-condensing boiler, almost certainly. Modern condensing boilers send far less heat up the flue. If you’re replacing a 10-year-old condensing boiler, the saving’s smaller and you’re really paying for reliability. Good controls and a lower flow temperature make a difference too.
Do I need a survey to get a proper price?
For a fixed price, yes. We need to see where the boiler is, how the flue will run, the gas supply and what condition the system’s in. Online prices assume everything’s simple. It’s the extras found on the day that turn a cheap quote into an expensive one.
How long is the guarantee on a new boiler?
It depends on the make and model. Most guarantees need the boiler registered after it’s fitted and serviced every year to stay valid. On selected Worcester Bosch boilers we can offer up to 12 years, and we guarantee our own workmanship for 12 months on top. Keep your service paperwork somewhere you can find it.
Want a price for your home?
Ring us on 01275 400 687 or get in touch online. We’ll come and look at what you’ve got and give you a free, fixed quote with no pressure to go ahead.