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How much does a new boiler cost?

You can live without a microwave, a barbeque, even your television. But try going without a boiler. No hot water. No central heating. Just wrapped up in a blanket with a hot water bottle – thanks to the kettle. Yes, they’re not cheap, what can you do if you need a new boiler?

How much they cost depends on what you know and who you speak to, as we explain here.

Engineer installing a new boiler


Replacing a boiler – what are the signs to look out for?

Before we get ahead of ourselves, it makes sense to consider what can be done to mitigate matters. Rather than wait until your boiler packs in, there’s no logic in turning a blind eye to tell-tale signs that it’s ailing.

Taking action means you might be able to correct any problem, or at least buy some time to save and research how best to proceed. With this in mind, here’s a breakdown – no pun intended – of some of the key warning signs to watch out for:

Your boiler lets you down a lot

If your boiler lets you down once or twice, you could put that down to strong winds or bad luck. But if it keeps happening, and you’re spending a small fortune on call-out charges, it might be worth going all out and getting a new boiler. After all, the point of a service is to ensure your boiler will tick along for the next 12 months without any problems.

Your energy bills are spiking

If you have a relatively old boiler the odds are it’s not energy efficient. Boilers are rated from A to G, and yours should have a label slapped on it that reveals it’s ranking.

Modern A-rated boilers are considered to operate at more than 90% efficiency, whereas a G-rated boiler will likely chug along at 70% efficiency.

Given the rising cost of fuel bills, your boiler’s efficiency rating can make a huge difference to your annual budget.

Your boiler is angry

If your boiler kicks off, rattling away and weeping water from it’s joints you might have a problem. Yes, central heating systems aren't silent, but you’ll soon tell the difference between the odd click or gurgle and a full-on audio assault.

Tapping sounds suggest a sludge build-up, which can be fixed with a shop-bought solution. But you need expert advice for more sinister sounding problems. If you regularly hear banging sounds, or sense a vibrating motion this could indicate a boiler breakdown issue.

Your boiler smells bad

Foul smells from a boiler can only be bad news. The internal organs of a boiler consist of metals and plastics. If either overheat they can let off gases, which can be dangerous.

Likewise, if you smell something similar to rotten eggs, be wary as this could point to a gas leak. In this case, shut off your boiler and call the gas emergency line on 0800 111 999 [LINK].

Your boiler is leaking

Boilers shouldn’t leak. Everything in them should be well contained and running smoothly. If you see even a drip, or vertical stain indicating one, this is a sign that all’s not right with the seals, valves or washers. You should get it seen to before it worsens.

Your radiators are struggling

Typically, you shouldn't notice this problem until the winter months, But, if you spot your radiators are cooler than they should be, even after bleeding them, then you may have a bigger problem that should be investigated.

Your thermostat is dying

Before throwing up your hands in defeat, check your thermostat isn’t the cause of the problem. If this device is malfunctioning, even the best boiler won’t deliver. Just bear this in mind when things go wrong. While a thermostat can be pricy its cost pales compared to that of a new boiler.


How much do new boilers cost?

The cost of a boiler depends on several factors. These include:

  • How easy it is to install
  • Whether the ideal placement is in line with the latest regulation (you must have an outside flue, for example),
  • The size of your property
  • Whether you live in a flat or a house
  • If you live in a flat, how many storeys up you are
  • What type of boiler you want or are willing to pay
  • Competition among qualified installers in your area

All things considered, the average cost of a new system boiler is up to £2,500 for a system boiler or a heat-only boiler. Combi boilers are a little cheaper at £2,000, according to Heatable.co.uk, but these prices don’t include labour, which can more than double the cost.

As ever, shop around, and if you’re planning on going low-carbon see whether you’re eligible for a low-carbon boiler grant.


Types of boilers

There are 3 main types of household boilers:

Heat-only boiler

A heat-only boiler provides central heating via a cylinder. Typically, the cylinder draws water from an ‘open-vent’ system comprising a ‘feed and expansion’ tank located in the loft areas. But they can also work off a ‘sealed’ system, which allows water to heat within a pressurised expansion container. As water cools it’s forced back into the system.


  • Easier to hook into an existing central heating system as it works well with incumbent radiators
  • Heat-only boilers tend to be cheaper to buy than the alternatives


  • Only the boiler will be covered by a guarantee or warrantee
  • All the other components, including the hot water tank, pumps and valves, which are vulnerable, aren't covered automatically

System boiler

System boilers also use a hot water cylinder, but in this case they’re not open vented, meaning no loft tank. Instead, all the components are housed within the boiler, which is typically found alongside an unvented hot water cylinder.


  • Can cope with high demand for hot water, making them a good choice if you have a larger family
  • Typically come with a robust manufacturer’s guarantee or warranty, which covers the many components that make up the boiler


  • Feeds off the mains (if this is lower in pressure the system might struggle)
  • Takes up more room than a combi boiler, which means they can be awkward to house

Combi boiler

A combi boiler does away with the need for a hot water cylinder in an airing cupboard. As the name suggests, it combines central heating and hot water supplies via a single unit, which is typically wall-hung.

This option saves space as it heats cold water via an integral heat exchanger direct from the mains supply.


  • Uses less space
  • Lower maintenance costs, as parts are covered by the provider’s warranty or guarantee
  • Heats water quickly


  • Less effective if you have low mains water pressure
  • Less effective if you have a larger property or if different appliances, such as if your shower and sink, are being used simultaneously
  • Can prove expensive if daily usage is high – making it better suited to smaller properties

What type of boiler do I need?

The type of boiler you need next will be dictated by your current circumstances. Here are the main points to consider:

  • If money’s tight you might want to consider replacing your current model with one that slots into the same space. It’s worth noting that regulations might not allow this if your flue, for example, doesn’t comply. This can be a real issue if you’re a landlord.
  • Likewise, if you want to keep costs down, a combi-boiler of the same dimensions, fitted in the same place could be a sound bet.
  • It makes sense to keep with an open-vented, heat-only boiler if your old pipework is buried in screed, unless you plan to re-plaster the room.
  • If you have a big family or house share it may make sense to opt for a system boiler that works off an unvented hot water tank. You need a plumber to assess what tank you have and whether your water pressure is adequate.

Home insurance with boiler cover

Home insurance is essential, but don’t kid yourself into thinking it covers every eventuality.

Many insurers exclude boiler repairs and replacement from their standard policies. Instead, they’re offered as an optional extra, typically under home emergency cover.

This gives you access to emergency repairs if you're suddenly left without central heating after a boiler breakdown.

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