Combi boiler installers · Gas Safe registered
Get a fixed-price quote for a new combi boiler online, pick your installation date and have a Gas Safe registered engineer fit it. Like-for-like combi swaps start from £1,759 fitted, and we also convert older tank-fed and system set-ups to a combi.
Replacing a combi boiler
A combi boiler heats your radiators and your hot water from one compact unit. It takes water straight from the mains and heats it the moment you turn on a tap, so there is no cylinder to wait for and no tanks in the loft. That simplicity is why combis are the most common type of boiler in UK homes.
Most combi jobs are straight replacements: an ageing combi swapped for a new, more efficient model in the same spot, usually in a single day. The rest are conversions, where we take out the hot water cylinder and loft tanks and free up the airing cupboard in the process. Either way, the price you accept online is fixed.
A combi is not right for every home. If two showers regularly run at once, or your mains flow is weak, a system boiler with a cylinder may serve you better, and we will say so before you buy. Weighing it up? Read our combi boiler pros and cons, or browse all our replacement boilers.
The cost of a new combi boiler comes down to the job, not just the boiler. A like-for-like swap in the same position is the lowest-cost option, from £1,759 fitted. Converting from a tank-fed or system boiler, moving the boiler or replacing an old back boiler adds pipework, flue and making-good work, so those jobs cost more. Every quote is fixed, so the price you accept online is the price you pay.
| Installation type | What’s involved | Price from | Time on site |
|---|---|---|---|
| Like-for-like combi swap | Replace an existing combi in the same position, with new flue, magnetic filter and controls | £1,759 | 1 day |
| Conventional or system to combi | Remove the cylinder and loft tanks, cap off redundant pipework, fit the combi and upgrade the gas supply if needed | £2,350 | 1–2 days |
| Combi boiler relocation | Move the boiler to a new room, loft or garage with new gas, flue and condensate runs | £2,250 | 1–2 days |
| Back boiler to combi | Remove the back boiler and fire, make good the fireplace and fit a combi in a new location | £2,795 | 2+ days |
Combi boiler finance: spread the cost from £23.26 a month. As an example, a £1,799 boiler over 10 years at 9.9% APR works out at £23.26 per month. Shorter terms, interest-free and buy now, pay later options are also available, subject to status. See our boiler finance options for the full details.
A combi only performs as well as the supply feeding it. These are the checks our engineers make so your new boiler delivers the hot water you expect.
A combi’s hot water depends on your mains. We check flow and pressure at the kitchen tap, so the boiler we fit can deliver a decent shower.
Combis draw a lot of gas when heating water. We check the pipe from your meter is large enough and upgrade it where it is undersized.
The flue has to meet clearance rules from windows, doors and boundaries. We reuse a compliant route or fit a new flue where the old one no longer qualifies.
Sludge in old radiators shortens a new boiler’s life. We clean the system, add inhibitor and fit a magnetic filter to protect the heat exchanger.
Condensing boilers produce water that has to drain away. We route the condensate pipe inside where we can, so it is less likely to freeze in winter.
We fit time and temperature controls and, in England, the extra energy-saving feature combis need, such as smart controls or weather compensation.
Combis suit most smaller and mid-sized homes. Here is how we decide whether one will work for yours.
With no cylinder or loft tanks, a combi fits in a kitchen cupboard and frees the airing cupboard for storage.
A combi heats water as it flows, so it works best where one shower or tap runs at a time. Two at once splits the flow between them.
Combi output sets your hot water flow rate. Around 24–30kW suits most flats and smaller houses, with 30–35kW for busier homes. We match it to yours.
Moving from a tank-fed system to a combi raises the pressure in your pipework. We check older radiators and joints can take it. See changing from a conventional boiler to a combi.
Heating only the water you use avoids the heat a stored cylinder loses, and a modern condensing combi recovers heat an old boiler sends up the flue.
Want a combi but need a little more hot water? A storage combi keeps a small built-in store for stronger flow. See the best storage combi boilers.
Fill out our simple online enquiry form. We just need a few details about your home to give you quotes for new boilers online.
Select a combi boiler that fits your specific needs. You have the option to pay up-front, or with instalments on finance.
Next you will be able to choose a convenient boiler installation date. One of our Gas Safe registered engineers will complete installation of your new boiler.
You can choose from one of our boiler servicing plans, giving you peace of mind and keeping your boiler running smoothly for years to come.
We fit combi boilers in flats, terraces and family homes across our service areas, including London, Manchester, Leeds, Birmingham and Sheffield. Off the gas grid? See oil boiler installation and LPG boiler installation. See all our service areas.
A like-for-like combi swap starts from £1,759 fitted. Converting from a conventional or system boiler starts from £2,350, because the cylinder and tanks come out and the pipework changes. Your online quote is fixed, so the price you see is the price you pay.
Most combi swaps are done in a day. Conversions, relocations and back boiler replacements usually take one to two days, sometimes longer where there is making good to do.
Usually, yes. We remove the cylinder, cap off the redundant pipework and fit the combi. We check your mains flow and hot water use first, because homes where two or more bathrooms are used at once are often better staying with a system boiler.
A combi needs reasonable mains pressure and flow to give a good shower. Your engineer measures both before fitting. If your supply is weak, we will suggest a different boiler type rather than fit one that disappoints.
It depends on how much hot water you use, not just the number of radiators. Around 24–30kW suits most flats and smaller homes, and 30–35kW suits larger homes with an en-suite. Your quote recommends a size for your home.
In most cases, yes, and it keeps the cost down. If you would like it moved, for example to free up a kitchen cupboard, we can relocate it from £2,250.
A Gas Safe registered engineer. We use subcontracted engineers, so we check each one is registered and qualified for the job. They commission the boiler, register the warranty and notify Building Control through Gas Safe Register.
Yes. Combi boiler finance starts from £23.26 a month, based on a £1,799 boiler over 10 years at 9.9% APR. Interest-free and buy now, pay later options are also available, subject to status.
Answer a few questions about your home, see fixed-price combi boilers and book the installation date that suits you – all online, in a few minutes.