Most UK homes pay between £2,200 and £5,500 for a heating system upgrade, supplied and fitted. The boiler is only part of that heating system upgrade cost. Controls, a magnetic filter, a system clean and sometimes a new hot water cylinder make up the rest, and they decide whether the system works well. This guide is about upgrading a gas heating system through our boiler and heating system upgrades service. It is not about the Boiler Upgrade Scheme, which is a grant for heat pumps.
Heating system upgrade cost by job size
Typical UK heating system upgrade costs, supplied and fitted
| Job size | What it usually covers | Typical cost |
|---|---|---|
| Small | Combi boiler swapped for a combi in the same place, new controls, magnetic filter and system clean | £2,200–£3,200 |
| Typical | Regular or system boiler replaced, existing cylinder kept, some radiators changed, new controls | £3,200–£4,200 |
| Large | Conversion to a combi, or a system boiler with a new unvented cylinder, boiler moved or pipework altered | £4,200–£5,500+ |
The top tier can run past £5,500 when the pipework changes a lot. A survey is the only way to get a firm figure, so treat the table as a way to sense-check quotes.
What a heating system upgrade includes
An upgrade is more than a boiler swap. Alongside the boiler, a good quote usually lists:
- A new boiler matched to the heat the home actually loses, not just the old boiler's size
- Modern controls, from a programmable room thermostat up to a smart one
- A magnetic filter on the return pipe to catch sludge
- A chemical clean or power flush of the circuit, then inhibitor
- A new hot water cylinder, if the home is changing from a tank-fed to a pressurised system
- Commissioning and the paperwork that goes with it
If you only want the boiler changed and nothing else, ask for that price separately. It will be lower, but the old system's sludge can shorten the new boiler's life, which is why many installers insist on a clean. Our power flushing page explains the options.
What changes heating system upgrade cost
- Boiler type. Swapping like for like is the cheapest route. Moving from a regular boiler with tanks to a combi means removing the tanks and altering pipework.
- Cylinder. A new unvented cylinder can add well over a thousand pounds, so decide early whether you need one.
- Position. Moving the boiler means a new flue, new gas pipe and often new condensate drainage.
- Radiators. Old, undersized or corroded radiators are often changed at the same time. See the radiator replacement page for those costs.
- Controls. A basic programmer costs little. A smart thermostat with a receiver costs more, and smart radiator valves in several rooms add to the bill.
- System condition. Heavy sludge means a full power flush instead of a quick chemical clean.
- Warranty. A longer manufacturer warranty usually comes with a dearer boiler and an approved installer.
Two quotes can differ by £1,000 or more because one includes a system clean, filter and controls and the other does not. Ask each engineer to itemise those, then compare like with like.
Is a heating system upgrade worth it?
A new boiler on its own may not fix cold radiators or slow heat-up, because the circuit matters just as much. If you are not sure whether the problem is the boiler or the pipework, start with central heating problems explained, and use the signs you need new central heating checklist if the system is old.
Getting a fair price
Get three written quotes, each after a visit to the property. Look each engineer up on the Gas Safe Register and ask how they will notify the work. The government's competent person schemes page explains why that matters. You can add up your own total with the heating cost calculator.
Frequently asked questions
How much does it cost to upgrade a heating system?
As a guide, most UK upgrades cost £2,200 to £5,500, supplied and fitted. A like-for-like combi swap sits at the bottom, and a conversion with a new cylinder sits at the top.
Is it worth upgrading a boiler that still works?
It can be, if the boiler is old, inefficient or costing you in repairs. If it works well and heats the house evenly, you may be better off waiting and looking after it.
Does the price include a system clean?
Often it does, but not always, so ask. Many boiler warranties expect the system to be cleaned when a new boiler is fitted.
Can I get a grant towards a gas heating upgrade?
Help for gas boilers is limited and changes often. Check the current schemes on gov.uk and your energy supplier's website before you rely on one.
Ready to talk to a boiler and heating upgrade specialist?
Get Free Quotes →