new combi boiler installation cost

New Combi Boiler Installation Cost

What is the usual new combi boiler installation cost?

The simple answer is it depends on your needs.  This article will give you detailed information on how much different types of combi boiler installations will cost.

If you’re new to the combi boiler world, it’d probably help to read about what is a combi boiler, and how a combi boiler works.

If you see a website advertising a new combi boiler installation cost, for ex. “£1695 inc. VAT for a new combi boiler on your wall!” that is possibly for the easiest new combi boiler installation cost, for ex. simply swapping your old combi boiler with a new one.  In many cases low prices may also be down to a cheaper, lower efficiency boiler with substandard parts.  So, if you’ve gotten quotes from several companies or plumbers, it’d probably be a good idea to do your research on the boiler brand, look at their reviews, and see what type of internal components they have, combi boiler efficiency, UK Best Buy rating etc.

Before we explain new combi boiler installation cost, it’d be a good idea to understand what type of boilers are usually converted to combi.  Below is an explanation of all types of combi boiler installations with their average cost range.

Convert Open Vent to New Combi Boiler Installation Cost

new combi boiler installation cost


With higher capacity combi boilers and storage combi boilers available now, this is soon becoming very common.  A decade or so ago we didn’t have powerful combi boilers, so the only option was to either get rid of attic tanks and convert to a system boiler, or replace the old open vent boiler with a new one.  But now we have larger capacity combi boilers (from 35kw to 38kW) and storage combi boilers for larger properties with 2 bathrooms and higher demand for simultaneous hot water demands.

If you do choose to convert your open vent boiler setup to a combi, a gas safe registered engineer will follow these steps:

  1. Draining of the existing heating & hot water system.
  2. Removal of the existing open vent boiler, hot water cylinder and attic tanks.
  3. Controls will be upgraded to ones suitable for a combi boiler.
  4. Or existing smart controls like Nest can be configured to work with the new combi boiler.
  5. All scrap will be carted away from site and recycled.
  6. The central heating system will be converted to combi.
  7. Gas run will be upgraded to 22mm pipes for modern, condensing combi boilers.

Once all that is done, the following will be installed:

  • Brand New, Modern Condensing Combination Boiler
  • Horizontal or Vertical Flue
  • Microbubble Deaerator [If the Client Wants it]
  • Magnetic Filter
  • Limescale Filter
  • Boiler Plus Compliant Programmable Thermostat
  • OR Internet Enabled Learning Thermostat
  • North Facing Weather Compensation
  • Chemical Flush & Add an Approved Inhibitor
  • Associated Pipe Work to Complete Installation
  • Registration of Extended 7-10 Years Warranties
  • Commission & Test to MFI & Complete Benchmark
  • Building Regulation Notification with Certification including Landlord Certificates
  • Hand Over & Induction on Boiler, Controls & Best Usage

Average Open Vent to New Combi Boiler Installation Cost:

£1,800 to £3,800* inc. VAT

*Depending on the options you choose.

Convert Sealed System Boiler to New Combi Boiler Installation Cost

new combi boiler installation cost

Pictured above is a Viessmann 100-W Sealed System Boiler and an Unvented Cylinder


Sealed System boilers don’t need to store cold water in expansion tanks in the attic/loft.  They only need the hot water cylinder for domestic hot water storage.  So to convert System  to Combi, the following steps need to be followed:

  1. Draining of the existing heating & hot water system.
  2. Removal of the existing System boiler and hot water cylinder.
  3. Controls will be upgraded to ones suitable for a combi boiler.
  4. Or existing smart controls like Nest can be configured to work with the new combi boiler.
  5. All scrap will be carted away from site and recycled.
  6. The central heating setup will be converted to combi.
  7. Gas upgrade to 22mm pipes for modern, condensing combi boilers.

Once all that is done, the following will be installed:

  • Brand New, Modern Condensing Combination Boiler
  • Horizontal or Vertical Flue
  • Magnetic Filter
  • Microbubble Deaerator [If the Client Wants it]
  • Limescale Filter
  • Boiler Plus Compliant Programmable Thermostat
  • OR Internet Enabled Learning Thermostat
  • North Facing Weather Compensation
  • Chemical Flush & Add an Approved Inhibitor
  • Associated Pipe Work to Complete Installation
  • Registration of Extended 7-10 Years Warranties
  • Commission & Test to MFI & Complete Benchmark
  • Building Regulation Notification with Certification including Landlord Certificates
  • Hand Over & Induction on Boiler, Controls & Best Usage

Average System to New Combi Boiler Installation Cost:

£1,800 to £3,800* inc. VAT

*Depending on the options you choose.

Swap Old Combi with New Combi Boiler Installation Cost

 

new combi boiler installation cost


This is possibly the easiest and quickest form of combi boiler installation.  Because your central heating is already working around a combi setup, all the installer needs to do is take out the old combi boiler, and install the new one.  In some cases the gas run will have to be upgraded to 22mm for modern condensing combi boilers.

  1. Draining of the existing heating & hot water system.
  2. Removal of existing Combi Boiler.
  3. If you choose to replace the controls, they will be removed too.
  4. Or existing controls can be configured to work with the new boiler.
  5. All scrap will be carted away from site and recycled.
  6. Gas upgrade to 22mm pipes for modern, condensing combi boilers. [If Required]

Once all that is done, the following will be installed:

  • Brand New, Modern Condensing Combination Boiler
  • Horizontal or Vertical Flue
  • Magnetic Filter
  • Microbubble Deaerator [If the Client Wants it]
  • Limescale Filter
  • Boiler Plus Compliant Programmable Thermostat
  • OR Internet Enabled Learning Thermostat
  • North Facing Weather Compensation
  • Chemical Flush & Add an Approved Inhibitor
  • Associated Pipe Work to Complete Installation
  • Registration of Extended 7-10 Years Warranties
  • Commission & Test to MFI & Complete Benchmark
  • Building Regulation Notification with Certification including Landlord Certificates
  • Hand Over & Induction on Boiler, Controls & Best Usage

Average Old Combi to New Combi Boiler Installation Cost:

£1,600 to £3,500* inc. VAT

*Depending on the options you choose.

Convert Back Boiler to New Combi Boiler Installation Cost

new combi boiler installation cost


This may be the most complicated combi boiler installation because there is a lot of work involved.  The old back boiler needs to be decommissioned and either left in place or removed if you want it.  Removal may require a lot of make-good work.  This installation in most cases also connects to a vertical flue instead of the commonly used horizontal flue, which adds to the cost.  Below are the steps involved with a Back Boiler to Combi Conversion:

  1. Draining of the existing heating & hot water system.
  2. Back boiler is decommissioned and left in place.
  3. Removing the back boiler can be a lot of work.
  4. Controls will have to be upgraded.
  5. All scrap will be carted away from site and recycled.
  6. Gas upgrade to 22mm pipes for modern, condensing combi boilers.

Once all that is done, the following will be installed:

  • Brand New, Modern Condensing Combination Boiler
  • Horizontal or Vertical Flue
  • Magnetic Filter
  • Microbubble Deaerator [If the Client Wants it]
  • Limescale Filter
  • Boiler Plus Compliant Programmable Thermostat
  • OR Internet Enabled Learning Thermostat
  • North Facing Weather Compensation
  • Chemical Flush & Add an Approved Inhibitor
  • Associated Pipe Work to Complete Installation
  • Registration of Extended 7-10 Years Warranties
  • Commission & Test to MFI & Complete Benchmark
  • Building Regulation Notification with Certification including Landlord Certificates
  • Hand Over & Induction on Boiler, Controls & Best Usage

Average Back Boiler to New Combi Boiler Installation Cost:

£2,200 to £4,500 inc. VAT

*Depending on the options you choose.

Full Central Heating with a New Combi Boiler Installation Cost

new combi boiler installation cost


If you’re installing a brand new central heating system around a combi boiler, the cost can be significantly higher compared to a simple combi boiler replacement.  A new central heating system installation includes radiators and TRVs (Thermostatic Radiator Valves) and Lock-Shield Valves.  Because it’s a brand new installation, installers don’t need to drain the existing system or remove anything.  They install the following:

  • Brand new Condensing Combi Boiler
  • Horizontal or Vertical Flue
  • Magnetic Filter
  • Microbubble Deaerator [If the Client Wants it]
  • Limescale Filter [If Required]
  • Boiler Plus Wireless Digital Programmable Thermostat
  • OR Internet Enabled Learning Thermostat
  • North Facing Weather Compensation [If Feasible]
  • New Gas Run from meter to Boiler
  • Radiators
  • TRV (Thermostatic Radiator Valves)
  • Lock-Shield Radiator Valves
  • Chemical Flush & Approved Inhibitor
  • All Associated Pipe Work to Complete Installation
  • Registration of Extended 7-10 Year Warranties
  • Commission & Test to MFI & Completion of Benchmark
  • Building Regulation Notification with Certification including Landlord Certificates
  • Hand Over & Induction on Boiler, Controls & Best Usage

Average Central Heating New Combi Boiler Installation Cost:

£4,000 to £6,000 inc. VAT

*Depending on the options you choose. Includes radiators, pipe runs, gas upgrades etc.

Which Boiler Brand and Installer Should You Consider?

Unbiased Recommendation for the Boiler Brand:

Viessmann.  Why? 

new combi boiler installation cost

  • UK Best Buy Status for 2nd Year Running 2017-2018
  • High Efficiency, Reliability and Durability
  • Patented Inox-Radial Stainless Steel Heat Exchanger (Unique in the UK)
  • Extended 7-10 Year Warranties (If installed by Boilerhut)
  • Most of the rivals (including Worcester Bosch) have Aluminium Heat Exchangers
  • Highest Energy Efficiency in the UK (94% to 98%)
  • Widest Range of Domestic Gas Boilers in the UK
  • Combined PRV (Pressure Release Valve) and Condensate
  • In-Built Shock Arresters

Biased Recommendation for the Boiler Installation Company

Boilerhut (Did you really think we’d recommend anybody else?) 😀

Why?

new combi boiler installation cost

  • Don’t take our word for it. Read our 5-Star Reviews.
  • Intelligent Quoting Tool gives you a Free, No Obligation Quote within Minutes.
  • Great, Fair Price. Boilers on Finance available.
  • Quote Finalized Same day. Installation can be done in days, not weeks.
  • Only the Most Experienced, Highest Quality Gas Safe Engineers.
  • PAS 2030 Accredited Company with Quality Management Best Practices
  • Helpful Articles, Boiler Reviews and Comparisons. Free Advice on Central Heating.
  • Extended 7-10 Year Warranties.
  • Excellent After-Sales Customer Support
  • Boiler Care Plans to Preserve Manufacturer’s Warranty


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