Cost to fit a new combi or system boilers

Replacing your old boiler with a new model has never been easier. Manufacturers are offering long warranties up to 10 year, even on cheaper models and there are plently of gas safe engineers willing to help with the installation.

Home boiler prices range from £700 to £5,000 and take from 1 to 3 days to install depending on your setup. The cheapest installation price is around £1,600 but expect to pay on average around £2,000 to £3,000 in total. 

Boiler installation hidden costs

Modern boilers are very efficient and easy to install for qualified gas safe engineers but removing your old system might create additional costs that you did not envisage. 

• Powerflushing the existing system using the old boiler to clean out corrosion debris might be a prerequisite of the heating engineer or new boiler manufacturer warranty. The existing radiators and pipes will have corrosion debris in them which needs to be cleaned out so it doesn’t clog up the highly efficient heat exchanger in your new boiler. Expect to pay between £300 to £800.
• Removing the old boiler - Your old boiler may have been bigger (new boilers are very compact), and had pipes running in different directions. So you might need to make good cabinets or walls before or after installing the new boiler. Painter & decorators or carpenters may be required.
• New location or configuration of boiler -  A boiler swap, usually a like for like combi boiler, is the easiest and cheapest installation with little pipework modifications required. For different boiler configurations the gas safe engineer will be required to adapt pipework and fit the new flue to suit the boiler. If you are changing the boiler location you may also need re-route the gas pipe that feeds it and power supply to control it. Keep cost down by choosing a boiler that is easy to swap.
• Fitting the new boiler - The engineer needs to make all the connections including, power supply, gas, mains water in, flow and return pipes, hot water out, flue, pressure relief pipe. Extras offered to customers include, corrosion debris filters, adding limescale inhibitor and system corrosion inhibitor. The boiler manufacturers warranty might depend on some of these extras.
• Replacing Gravity fed (open) system - If you replace with a combi or system boiler you will need to remove the old hot water tank and the expansion tanks in the loft. The engineer will be happy to take away the copper hot water tank and copper piping because they have value but might be more reluctant to remove the expansion tanks in the loft. If you want these removed make it clear to the engineer who will probably add it to his quote.
• Smart heating controls - Most modern boilers can be controlled by smart heating controls so it would seem a good idea to upgrade on installation. They cost between £100 and £200 and take a couple of hours to install.
• Register new boiler - The engineer should register your new boiler installation on the Gas Safe Register and also activate your manufacturers warranty with the supplier.

Extra costs to consider when getting a new boiler

How much do Combi boilers cost?

Image	Name	Cost
	Glow-Worm Compact 28kW Combi Boiler	£643.19
	Worcester Bosch Greenstar 2000 25kW Combi Gas Boiler	£881.80
	Glow-Worm Energy 30C Erp Combi Boiler	£1005.59
	Baxi 630 Combi 2 Boiler	£1036.79
	Ideal Logic2 Max C24 24kW Combination Boiler	£1166.03
	Worcester Bosch Greenstar 8000+	£1662.32
	Vaillant ecoTEC Plus 836 36kW Combi Boiler	£1754.99
	Vaillant EcoTEC Plus 840 40kW Combi Boiler	£1972.79
	Viessman Vitodens 200-W 32kw	£1988.16
	Worcester Bosch Greenstar 8000+ 45kW Combi Boiler	£2321.99

What are combi boilers?

Combi boilers (combination boilers) are compact small boilers which both heat water directly which comes out of your hot taps and also send hot central heating water to your radiators to heat your home.

How do combi boilers work?

To get your radiators hot the system water in your home's radiators and pipes is circulated using a pump through the combi boiler’s main heat exchanger which is heated by a gas burner.

When you turn on a hot water tap or shower a flow sensor tells the combi boiler’s diverter valve to redirect the heated system water internally through a second ‘plate to plate’ heat exchanger which indirectly heats up mains water and in seconds sends the now hot mains water to your hot tap or shower.

Why are combi boilers so popular?

No space needed for hot water cylinders or water tanks, low cost, range of out-puts to suit all properties, simple to install, maintain - all persuasive reasons why combi boilers are the number one choice when UK homeowners buy a new boiler.

Worcester Bosch combi boilers

• Greenstar 2000 Combi boiler (25/30kw) - Suitable for one bathroom small to medium homes, fits between standard kitchen cabinets. Quietest in range, efficient and guarantee ranging from 5 – 6 years.
• Greenstar 4000 Combi boiler (25/30kw) - Ideal for small to medium homes with one bathroom. Modern design, easy to use colour display, efficient, quiet and guarantee ranging from 7 - 8 years.
• Greenstar Si Compact Combi boiler (25/30kw) - Suitable for small to medium homes with one bathroom, fits into a standard kitchen cupboard, easy to use controls and guarantee ranging from 7 – 8 years.
• Greenstar CDi Compact combi boiler (28/32/36kw) - suitable for small, medium and large-sized properties with one or two bathrooms. Compact enough to fit into a standard kitchen cupboard but powerful enough for homes with more than one bathroom. Guarantee ranging from 7 - 8 years.
• Greenstar 8000 Life Combi boiler (30/35/40/45/50kw) - most powerful wall hung combi boiler range with a modern design, wireless connectivity and guarantee ranging from 8 – 10 years.
• Greenstar 8000 Style Combi boiler (30/35/40/45/50kw) - Top of the range, look like huge black or white wall hung iPhones, connected technology and power to comfortably heat large homes with two or more bathrooms. Guarantee ranging from 8 – 10 years.

Vaillant combi boilers

• ecoFIT pure combi (25/30/35kw) - compact to fit in a cupboard so suitable for small homes. Efficient, quiet, smart controls and guarantee ranging from 2-10 years.
• ecoTEC pro combi (24/28/30kw) - smart boiler for small to medium homes. Full range of thermostat controls (from analogue timers to ySMART app controlled) and 2-10 years guarantee.
• ecoTEC plus combi (25/32/35/38kw) - high performance, precision control and efficiency suitable for any home and 5-10 years guarantee.
• ecoTEC Green iQ combi (35/43kw) - best in range for efficiency and control, fully compatible with vSMART app, 85% recyclable and 5-10 years guarantee.

How much do system boilers cost

Image	Name	Cost
	Glow-Worm Energy 30S System Boiler	£1210.79
	Vaillant ECOTEC PLUS 630 System Boiler	£1664.50
	Worcester Bosch Greenstar 8000+ 35kW Gas System Boiler	£1791.32
	Viessmann Vitodens 200-W	£1988.16

What are system boilers and how do they work?

System boilers are a great solution for large family homes as they provide a constant supply of hot water for baths, showers and washing up. A system boiler works by filling a large, insulated storage cylinder with hot water so there is a constant supply of hot water ready to be used at any time.

Worcester Bosch system boilers

• Greenstar 4000 System boiler (12/15/18/21/24kw) - Suitable for one bathroom small to medium homes. Modern design, quiet, easy to use colour display and guarantee ranging from 7 – 8 years.
• Greenstar I System boiler (27/30kw) - Small but powerful, suitable for small, medium and large homes whilst fitting into a standard kitchen cupboard, easy to use controls and guarantee ranging from 7 – 8 years.
• Greenstar 8000 Life System boiler (30/35kw) - most powerful wall hung system boiler range with a modern design, wireless connectivity and guarantee ranging from 8 – 10 years.
• Greenstar 8000 Style System boiler (30/35kw) - Top of the range, look like huge black or white wall hung iPhones, connected technology and power to comfortably heat large homes with two or more bathrooms. Guarantee ranging from 8 – 10 years.

Vaillant system boilers

• ecoFIT pure system (12/15/18/25/30kw) - compact to fit in a cupboard so suitable for small homes. Efficient, quiet, smart controls and 2-10 years guarantee.
• ecoTEC plus system (12/15/18/24/30/37kw) - high performance, precision control and efficiency suitable for any home and 5-10 years guarantee.
• ecoTEC Green iQ system (27kw) - best in range for efficiency and control, fully compatible with vSMART app, 85% recyclable and 5-10 years guarantee.

Conventional boilers

Image	Name	Cost
	Glow-worm Easicom 3 25kW Boiler	£618.00
	Vaillant ecoFIT Pure 412 Boiler	£990.00
	VAILLANT ECOTFIT PURE REGULAR	£1192.00
	Vaillant ecoTEC Plus 424 boiler 24kW	£1381.00
	Worcester Bosch Greenstar 8000+ 35kW Boiler	£2007.00
	Keston Heat 2 55kW Boiler	£2701.00

Estimates for common heating engineer jobs;

Rates for other trades