PLANNING GUIDES
New central heating system: The complete planning guide
Updated 08/26
By: Imogen Beech
Reviewed: Kim Staples
Installing a central heating system for the first time? Or think your existing central heating needs an upgrade? Here’s all you need to know.
Whether you actually need a full system replacement
Which boiler type suits your home
What to consider when choosing a boiler and radiators
How much a new system typically costs
How to find a qualified installer
Investing in a new central heating system can reduce your monthly heating costs, improve your home’s energy efficiency, and give you greater control over the way you heat your home.
But if you’re hoping to install a new central heating system, it can be tricky to know where to start.
Don’t worry. Here, we’ll go through everything step-by-step so you can plan your central heating installation without a hitch.
What is a central heating system?
A central heating system consists of pipework and radiators (or underfloor heating) that are connected to a boiler. The boiler heats up water, which moves through the pipework to your radiators.
In this way, it’s able to warm up the various rooms of your property, before travelling back to the boiler for reheating.
Often – but not always – the same boiler will also provide hot water to the taps in your home.
If you’re renovating a period property that doesn’t yet have central heating, this is likely one of the first jobs you’ll want to plan for. After all, central heating is key to providing you with warmth and comfort in your home.
But this isn’t the only scenario in which you may need a new central heating system. Rather, replacing your existing central heating could help you improve your home’s energy efficiency, lower your energy bills, and reduce your carbon footprint. This brings us onto…
Signs it's time to replace your central heating system
There’s no exact timeline for when to replace your central heating system - but the following signs may be a hint that it’s time to make a change:
Your heating bills are going up
You’re always forking out on repairs
You’re constantly adjusting the thermostat
Your home is being heated unevenly
Your heating is running for short, frequent cycles
The boiler makes strange noises
You feel uncomfortable at home
Your boiler is getting old
As a general guide, you should consider a boiler upgrade roughly every 10 to 15 years, even if your boiler is working okay. This is because newer boilers are typically much more efficient and environmentally friendly than their older counterparts.
Meanwhile, you’ll need to replace your radiators around every 15 to 20 years.
You don't have to replace the boiler and radiators together, but doing a full system upgrade at once is often more cost-effective than tackling each part separately, and it means less disruption overall.
If you're planning other renovation work - a loft conversion or extension, for example - it's far easier and cheaper to sort your heating before flooring and decorating go in.
Key parts of a central heating system to plan for
There are lots of different elements to your central heating system. Sometimes, it can be hard to know which parts you need to replace when you’re embarking on an upgrade.
Here are the different options you’ll need to consider.
1. Boiler
Your boiler is the central unit that provides heat – so, it’s key to a good central heating system. You’ll need to choose one that’s suited to your property’s needs.
Efficiency
While a more efficient boiler will cost more, it will also save you on energy costs in the long run – as well as being better for the environment.
New boilers today have to be A-rated, with a minimum of 92% ErP efficiency (ErP, which stands for ‘Energy-related Products', is a European rating system for boilers and other heating appliances).
Type
Replacing your boiler like-for-like will cost less than converting it to a different type. But if you’re not happy with the type of boiler you have currently, now could be the perfect time to change it.
Nowadays, there are three main types of domestic boilers:
Combi boilers don’t need a storage tank and are able to heat water straight from the mains
System boilers use hot water cylinders but don’t have cold water tanks
Conventional boilers rely on a storage cistern with two feeds: one for hot water and one for cold
Combi boilers are the most popular gas boiler type used across the UK today. They’re economical, and don’t take up much space, thanks to the fact that they don’t need cold water tanks or hot water cylinders.
Plus, a combi boiler will give you unlimited hot water whenever you want. This is in contrast to system and conventional boilers, which only hold a certain amount of water that has to be heated in advance.
Head over to our guide on the best boilers for central heating to learn more.
Position
Again, moving your boiler to a new location will cost more than installing your new boiler in the same place as your old one, because the installation will be more complex and take longer to complete.
However, if your boiler is currently taking up valuable space, moving it to a new location – for instance, your loft – could be a great solution.
2. Radiators
Modern radiators can be up to 50% more efficient than old ones and can channel water more efficiently too, meaning lower energy bills.
Size
It’s important to make sure you choose the correct size radiator to heat each room of your house efficiently.
To calculate the right size, you can use a BTU (British Thermal Unit) calculator.
Material
Radiators come in a range of different materials, some of which are better conductors than others.
Aluminium is arguably the best radiator material. As a superconductor, aluminium radiators can heat up rooms quickly.
They also tend to use less water than other kinds, so less energy is needed to heat the water and pump it around your heating system.
Head over to our guide on the most efficient radiators to learn more.
Location
Replacing your radiators without changing their location will be the most cost-effective option.
But sometimes, moving the position of your radiators can open up more design options – or even help to heat a room more efficiently.
Radiators are usually installed beneath windows to combat heat loss through the window. That said, placing your radiators adjacent to the window can also be effective for heat control – especially if your windows reach to the floor.
Aesthetics
Radiators come in all shapes, sizes, colours, and materials. In fact, instead of being purely functional, modern radiators can often form the focal point of a room.
While a cast iron column radiator can look beautiful in a period property, a modern extension might benefit from a slick, space-saving vertical radiator.
Check out our radiator ideas for some inspiration.
3. Smart thermostatic radiator valves (TRVs)
It can be a good idea to install smart thermostatic radiator valves along with your new radiators – or even on your existing ones.
Thermostatic radiator valves have a dial that allows you to control the temperature of each individual radiator in your home.
Meanwhile, smart thermostatic radiator valves actively monitor your activity in each room and use this information to heat your rooms accordingly.
They also let you program your radiators from your smartphone, so it's easier for you to control your home’s level of heating to suit your needs – and save energy.
4. Thermostat and controls
Every new boiler has to be installed with a thermostat, and it's generally worth replacing an old one at the same time rather than keeping it.
New boiler controls need to be Boiler Plus compliant to meet Building Regulations Part L - which older thermostats usually aren't.
Doing this alongside your boiler installation also works out cheaper than a separate job later.
And again, you could use this opportunity to upgrade to a smart thermostat system like Hive or Tado, to stay in control of your heating from your smartphone.
Head over to our guide on the cost of a smart thermostat to find out more.
5. System filters
Over time, sludge can build up in your radiators and stop them from heating to full capacity.
Sludge is essentially rust that’s released from the metal pipes and radiators in your central heating system, and collected by the water running through it.
To prevent this from happening, you can fit system filters to the return pipes on your boiler, which use powerful magnets to collect sludge.
6. Pipework
Replacing the pipework can be a costly, messy job. So, you’ll be pleased to hear that there’s usually no need!
That said, there are a few scenarios where you might want to consider it.
Kettling
If your boiler is kettling (where it makes a noise similar to a kettle), this could be down to a fault with your pipework. For instance, a leak or a build-up of sludge.
In this case, it’s worth getting your pipework checked by a heating engineer before installing a new boiler, to make sure it’s not the culprit.
Uneven heat
Have you found that your pipework is very hot coming out of the boiler, but the radiator temperature isn’t as hot?
This could indicate an issue with your pipework such as corrosion or a pinhole leak - and may mean it's worth considering replacing your pipework.
Stainless steel
Nowadays, central heating systems use copper pipes. But some older houses might still have stainless steel pipes – although this is quite rare.
If you find that your central heating system uses steel pipes, it could be a good idea to get them replaced. Stainless steel is more susceptible to corrosion, which can lead to both kettling and a build-up of sludge – neither of which you want!
7. Making good
Whatever options you choose, the chances are you’ll need to invest in at least some ‘making good'.
Essentially, even if you only replace your boiler, you’ll likely be left with internal or external holes from where the old boiler or pipework was removed.
While your installer may make good by filling the holes, they won’t typically plaster or decorate.
Remedial work needed might include:
Talk to your central heating engineer before they start so you can get a better idea of the remedial work needed after your new central heating system has been installed.
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How much does a new central heating system cost?
The cost of a new central heating system will depend on several factors, including the:
Size of your property
Number of bedrooms
Type of fuel (gas, electric, or oil)
Distribution pipework
Number of heaters or radiators needed
That said, you can expect to pay around £5,000to install central heating in a four-bedroom, two-storey house, plus around£1,300–£2,000for anew boiler and installation.
For a house this size, you'd need around ten radiators, which would cost you around £1,500 to install (including parts).
You'd also need your pipework, which costs around£1,000 for supply and installation.
And you should expect to pay around £220 for the water tank.
Get itemised quotes from a few different engineers so you can compare exactly what's included - whether that's the boiler, radiators, pipework, controls, and removal of the old system.
Just bear in mind that these figures don’t include any remedial work such as plastering and painting. It’s also wise to budget a little extra for any additional parts that are needed, or other work that your engineer comes across on the job.
Hire a tradesperson to install your new central heating system
Although you may be able to carry out small jobs on your central heating system yourself – like replacing the radiators – installing a full central heating system isn’t a job that you should consider completing on a DIY basis.
It’s complex, extensive, and technically challenging work that you don’t want to risk getting wrong. Plus, there are parts of the job that you won’t legally be able to complete yourself – such as boiler installation.
For this, it’s vital that you hire a competent fitter who’s properly registered and follows building regulations at all times.
Luckily, you're in the right place to start finding the right engineer with Checkatrade!
Simply enter your postcode into the search box to get started.
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All our tradespeople have to pass up to 12 checks and adhere to our standards to get listed on our directory. Plus, we check all the reviews on Checkatrade are from real people, so you know you can trust what you read.
Need reassurance? All tradespeople pass up to 12 checks before joining, and we keep checking after.
In fact, we’re so confident in the quality of the trades on Checkatrade that if you book through us, we guarantee their work up to £1,000 (T&Cs apply).
FAQs
A straightforward installation in a smaller property typically takes around 2-3 days, while larger or more complex jobs - especially those needing extensive pipework - can take longer.
No, installing central heating doesn't usually require planning permission, though building regulations apply to the work itself, and it must be signed off by a registered engineer.
No. Small jobs like swapping a radiator are sometimes DIY-friendly, but a full installation isn't. Boiler work legally requires a Gas Safe registered engineer for gas systems, or an OFTEC-registered engineer for oil.
You don't have to, but doing both together usually costs less overall and causes less disruption than replacing them separately over time.
A combi boiler heats water on demand with no tank; a system boiler uses a hot water cylinder but no cold tank; a conventional boiler uses a storage cistern with separate hot and cold feeds. Combi boilers are the most common choice in UK homes today.
Not usually. It's only worth considering if you notice kettling, uneven heat between the boiler and radiators, or if your home still has older steel pipework.
Often, yes - even a boiler swap can leave holes to fill. More extensive work, like new pipework, may require plastering, decorating or new flooring afterwards.
Look for Gas Safe (or OFTEC, for oil) registration, itemised written quotes, and reviews you can trust. Checkatrade checks every tradesperson on the platform and verifies their identity.
Need any help planning your central heating? From costs and maintenance tips to user guides and tips for being economical, we know you want a job done right.
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