Cost to buy and install new combi or system boilers

See the trade cost for combi & system boilers and how much local heating companies near you will charge for installing your new boiler (whether it is a like for like combi swap or installing a system boiler in a new location).

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.

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.

How much do Worcester Bosch combi boilers cost?

• 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.

How much do Worcester Bosch system boilers cost?

• 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.

How much do Vaillant combi boilers cost?

• 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 Vaillant system boilers cost?

• 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.

Boiler installation steps

There is more to getting a new boiler than choosing a brand, boiler type and then getting a gas safe registered engineer to fit your new boiler to the wall.

• Powerflush existing system using old boiler to clean out corrosion debris. 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 low water content (ie very small holes) heat exchanger in your new boiler
• Remove old boiler – say goodbye to your old faithful boiler (hanky handy for tears). Your old boiler may have been bigger, had pipes running in different directions and so some making good of cabinets or walls may be required.
• New location or configuration will require adapting pipes, flue to suit new boiler. Different boilers have pipes coming and going from different positions and so some local alignment of pipes and flue may be required.
• Fit new boiler. The big event….up goes the new shiny white box onto the frame and make all the connections (power supply, gas, mains water in, flow and return pipes, hot water out, flue, pressure relief pipe….anything else?).
• Recommend extras to customer; corrosion debris filter, limescale inhibitor, smart controls, system corrosion inhibitor, bleed radiators, top up system pressure
• Commission whole central heating system, explain to customer how to top up pressure, bleed radiators, set timer/thermostat/controls
• Register new boiler for Gas Safe Register and manufacturer warranty

Extra costs to consider when getting a new boiler