Latest Boilers & Installation Prices (£££)

We provide an estimate of fitted cost based on common scenarios for combi, system, heat-only and back boiler replacements. For example, the cost of a combi to combi or a heat only to a combi or a combi to a system boiler. All of our prices include parts, labour and VAT. 

Boiler installation cost scenarios

1) Cost to install a Heat Only (regular) boiler

Regular boilers are ‘heat only’ boilers. Very simply, the boiler will provide the heating and a cylinder will provide hot water.

The two scenarios below show rough costs for 1) replacing a regular boiler in its existing location and 2) a rough cost for installing a new regular boiler in a new location. The cost of a mid-range heat only boiler in this scenario is £750.

The cost for moving the boiler will vary according to whether it will be in the same room or moved to another room. In both cases we have assumed the cylinder and all other existing equipment are left in place.

Installation of a new heat only boilerApprox cost with mid range boilerTime taken
1) Replacing an existing heat only boiler
with a new boiler, in the same location
£1,7501 day
2) Replacing an existing heat only boiler
with a new boiler, in a new location
£2,2001.5 days

2) Cost to install a Combi boiler

Combination boilers provide heating and hot water via the boiler (there is no cylinder). There are two main scenarios for combination boilers: A) The new combi boiler is replacing an existing combi boiler or B) the new combi boiler is replacing a regular boiler and hot water cylinder. The cost of a mid-range heat only boiler in this scenario is £900.

A) Replacing an existing combi boiler

The two cost scenarios below show rough costs for a new combi boiler in the same location and for installing a new combi boiler in a new location. Again the cost for moving the boiler will vary according to where it is moved to.

Installation of a new combi boilerApprox cost with mid range boilerTime taken
1) Replacing an existing combi boiler
with a new boiler, in the same location
£2,0001 day
2) Replacing an existing combi boiler
with a new boiler, in a new location
£2,6001.5 days

B) Replacing a regular boiler and hot water cylinder with a combi boiler

In this scenario, there are a lot of additional works to remove the hot water cylinder and re-direct the hot water pipes to the new combi boiler location.

Conversion to a new combi boiler systemApprox cost with mid range boilerTime taken
1) Replacing an existing regular boiler and
hot water tank with a new combi boiler
£3,2002.5 days

3) Cost to install a System boiler

System boilers provide heating and work with an unvented hot water tank to provide hot water. System boilers are very high performing and are usually fitted in larger properties with multiple bathrooms.

It is unlikely that someone would wish to swap their existing system boiler and unvented hot water tank for a combi or heat-only boiler, so we have concentrated on common scenarios and provided rough costs for 1) replacing a system boiler in its existing location 2) replacing a heat-only boiler/vented cylinder with a system boiler/unvented hot water tank, 3) replacing a combi with a system boiler/unvented hot water tank (common for those extending their properties). In all cases we have assumed the boiler goes in the same location as the existing boiler. The cost of a mid-range heat only boiler in this scenario is £850.

Type of boiler replacement – average figures.
Price will vary according to scope of works.
Approx cost with mid range boilerTime taken
1) Replacing a system boiler with a new system boiler
and retain the unvented hot water tank
£1,9501 day
2) Replacing a heat-only boiler and hot water tank
with a system boiler and unvented hot water tank
£4,2002 days
3) Replacing a combi boiler with a system boiler
​and unvented hot water tank
£4,6002.5 days

4) Cost to replace a Back boiler

It is no longer possible to replace a back boiler with another back boiler.

We have provided two approximate costs for replacing a back boiler:

1) The back boiler is removed and replaced with a heat-only boiler, but the hot water tank is retained.
2) The back boiler and hot water tank are removed and replaced with a combination boiler

Type of boiler replacement – average figures.
Price will vary according to scope of works.
Approx cost with mid range boilerTime taken
1) Replacing a back boiler with a new heat only boiler
and retaining the hot water tank
£2,7752 days
2) Replacing a back boiler and hot water tank
with a new combi boiler
£3,2002.5 days
3) Replacing existing back boiler with a new style boiler
​and decorative fireplace
It is currently not possible to install a new back boilerNA

Basis for our cost guides

We have provided some estimated installation costs for four common scenarios (below).

  • 1) Heat Only (regular) boiler installation
  • 2) Combination boiler installation
  • 3) System boiler installation
  • 4) Back boiler replacement

We have assumed a mid–range boiler cost for a three-bed house with a standard installation set up. Most companies now include a power flush at no extra cost when fitting a new boiler and our prices assume this has been included. NB there may be additional costs for example if:

  • the gas pipe is undersized and needs to be re-run
  • the system requires a condensate pipe for the first time
  • the system needs to be sealed (i.e. there are currently expansion tanks in the loft)
  • there are some building works, for example to brick up a large existing flue hole

Why do fitted boiler prices vary so much?

Why do fitted boiler prices seem to vary so much? To some extent the cost of a boiler installation has always varied depending on who you use, but new operators in the market have changed the landscape again. We guide you on the different operators and changes that affect you.

British Gas and other big companies

At one time, a British Gas boiler installation could cost 50% more than a local sole trader and for often a lessor boiler. Why? Overheads are bigger for one. British Gas has a huge back office of support staff, sales staff and a network of largely employed engineers. It is however precisely because of this facility that British Gas can for many be a reassuring company to use.

All anyone wants is to be able to get support quickly if anything goes wrong and this can be reason enough to pay the extra. That said, the popularity of British Gas boilers remains with older generations, which suggests the model may tail off over time.

Sole traders

At the other end of the spectrum are sole traders. Usually a single engineer, often with an apprentice, working out of their van. Their overheads are lower, which they can pass onto the customer by way of lower labour charges. The downside is getting a return visit fast if something goes wrong. 

Small businesses in your area

Offering prices somewhere inbetween British Gas and a sole trader, the small local business often has one or two office staff, a few teams of engineers and has invested in systems and procedures. Many of us feel strongly about supporting a local business and we are willing to pay a small premium – over that of a sole trader – to get some intermediate level reassurance from our purchase.

Online companies with sub contractor networks

Between British Gas, sole trader, local business, it is fairly easy to understand where the price differences are, but they are no longer the only operators. The last three years have seen the emergence of online companies that provide a quote for a new boiler without a home visit. In this setup, each customers’ contract is with the online company, but they use a sole trader subcontractor to fit the boiler.

In terms of prices, the online quote companies are able to offer sole trader level prices via a national platform. Firstly because they have dispensed with the need for someone to visit the property and secondly because they can purchase boilers in bulk for bigger discounts. So if you get a price online from such a company, and there are many, you know why they are cheaper despite having a national, British Gas style, presence.

Online quotes from mainstream providers

The popularity of providing quotes online has ballooned over the last 2-3 years with mainstream operators such as British Gas now providing an option to buy a combi boiler online. Even some boiler manufacturers have invested in online quote technology in order to generate work their network of accredited installers. However both still result in a boiler installation without a home visit as the engineer will not have visited the property before the work commences.

A cautionary note on online quotes without a home visit

Many in the industry have argued that low online quote prices are in fact unsustainable and are designed to harness market share. The models have not been going long enough to know either way. What is important to know is the service you are buying. This is a packaged up sole trader installation, but the engineer will not have seen the job before arriving to fit the boiler.

We still advocate a home visit and there is nothing to be lost from engaging with a local sole trader, a small local business and an online quote company to see what each specify and price. The danger of quotes without a home visit is that the system is not properly designed. Too often we find oversized boilers and incompatible controls that do not maximise the efficiencies of the boiler. Such a casual ‘one-size-fits-all’ approach to boiler installations does nothing to ensure we fit correctly sized boilers onto systems that operate efficiently.

How much does a stand-alone boiler cost?

Boiler prices vary considerably as a result of build qualities and levels of after-sales support. As a general rule, budget boilers can offer shorter life spans, shorter warranties and reduced levels of customer support. Whilst they are cheap to install they tend to be expensive to maintain and less efficient to run.

Those considering replacing their gas boiler will be presented with a wide range of boiler manufacturers with little insight as to why prices vary so much. We want to cut through the detail and provide you with the salient details. The easiest way to sum up the variations in price and quality is to undertake a specific comparison on similar models.

We have created a comparison table (below) to compare a typical 24kW combination boiler from budget, lower-range, mid-range and high end models. Not all of the specifications will apply to every boiler in that category, but most will and importantly it will give you the information to ask the right questions.

Want more specific boiler prices? We provide three incredibly comprehensive guides to boiler prices that review the prices, efficiencies, size, warranty and hot water flow rates of ALL of the boiler models from popular boiler manufacturers.

Price comparison tableEntry LevelEconomyMid RangePremium
Approx cost of boiler only£685.00£775.00£975.00£1150.00
Efficiency89% – 91%89% – 91%92% – 94%92% – 94%
Warranty2-5 years5-7 years7-8 years8-10 years
After-salescareStrict terms that must be met for the manufacturer to honour warrantyReasonable terms ​that must be met for the manufacturer to honour warrantyNo quibble guarantee to repair or replace (betters any warranty cover)No quibble guarantee to repair or replace (betters any warranty cover)
T&CsCustomer must pay for an engineer to attend. Money is refunded if all paperwork is present and genuine fault foundCustomer MAY have to pay a deposit which will be refunded if access is granted and it is a genuine manufacturer faultNo quibble call out. Customers not required to pay for a visit. Will repair without fuss. Includes programmers, filters and tanksNo quibble call out. Customers not required to pay for a visit. Will repair without fuss. Includes programmers, filters and tanks
Call centre opening hoursMon – Fri onlyMon – Fri, Sat & Sun AMMon – Sat. Sun AMMon – Sat. Sun AM
Who attendsSub contracted engineersManufacturer’s engineersManufacturer’s engineersManufacturer’s engineers

Results overview

​At the budget end the boiler is nearly half the price of an upper end boiler. However the call centre is only manned Monday – Friday and the warranty terms are strict with lots of wriggle room for the manufacturer to refuse to honour it.

At the mid – upper end of the market customers benefit from long term, no quibble guarantees, better life expectancies and long hours of opening. Many of our manufacturers offer Accredited or Approved Installer Schemes that improve your warranty terms.

The perils of over sizing boilers

It is very common to oversize boilers ‘just in case’. It is in fact extremely inefficient. Oversized boilers ‘cycle’ excessively – bringing the boiler on and off too much – and accelerate wear and tear. Moreover, as standard TRVs will not reduce the output of the boiler as individual room temperatures are met, so the boiler continues to fire at the same high rate until all the rooms are warm.

To fully understand the implications on efficiency, a quick bit of technical talk is required, but it’s very easy! Boilers output at 70 degrees C. In order for the boiler to operating in ‘condensing mode’ – which is when it is 90% efficient or more – the temperature of the water back to the boiler must be 50 degrees C or lower. In other words, 20 degrees of heat must be dissipated through the radiators as the water goes around. If the boiler is oversized, combined with really any standard or thermostatic TRV, then it will never operate in condensing mode. 

Two things can be done to ensure the return temperatures are low enough:

1) ‘Range rate’ the boiler down to meet your heat requirement. The average heat requirement for a UK home is 6-8kW degrees at peak times. Most fitted boilers are 15kW! It is possible to range rate them down so that they meet your property’s needs and check with your engineer that this has been done. To work out the heat requirement of your home the attending engineer should carry out a heat loss survey.

2) Fit Eclipse TRVs by IMI Hydronics. Now we are a fully impartial website and as such products are only actively recommended based on their merits – we receive no sponsorship. The Eclipse TRV is the only TRV currently that will shut down radiators and signal the boiler to reduce its output. Eclipse TRVs will solve overheating in the system and increase efficiencies by up 16%. As a site dedicated to reducing our gas consumption, we highly recommend this product. The cost is on par with standard TRVs.

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