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Last updated: 14th May, 2024


Should You Convert to a Combi Boiler?

Should You Convert to a Combi Boiler?

If your boiler is over 15 years old or in need of a replacement, you should consider replacing it with a combi boiler. Combi boilers are a brilliant replacement for when you want to increase efficiency and space in your home.

Keep reading to discover what a combi boiler is and why our expert team at iHeat would recommend making the change. 

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Your Current Boiler-

First, let’s look at your current boiler. A ‘conventional system’ refers to a heat-only boiler with two cold-water tanks in the loft space and a hot water tank usually found in the airing cupboard. 

New system boilers are very similar to heat-only boilers. However, they don’t require the feed and expansion cold-water tanks in the loft. 

What Is A Combi Boiler And What Are Their Benefits?

Combi (combination) boilers link a home’s central heating system and water heating into a single unit, with all components integrated within the boiler. 

The combi signals a sensor upon hot water demand, then takes water directly from the mains, and the heat exchanger heats it for distribution to water outlets. This means there's no accompanying cylinder or hot water tank. This allows a compact boiler which could fit into a standard kitchen cupboard or be wall mounted, to thoroughly heat a home without stealing lots of space. Combi systems are also easier to service or for boiler replacement due to their popularity, meaning greater availability.

Another great benefit of a combi boiler is its efficiency. By heating water on demand instead of constantly heating stored water, you can save energy and cut fuel bills. A new combi boiler should be around 90% efficient, so replacing your old boiler could save you up to £380 according to The Energy Saving Trust.

Age of Boiler

Efficiency Percentage

Efficiency Rating (ErP)

0+ Years

90% +


10+ Years

85% +


15+ Years

80% +


20+ Years

70% +


25+ Years

60% +


The direct correlation between a boiler's age and efficiency is clear in the newer systems’ ErP. 

Should I Swap to a Combi Boiler?

A combi boiler is a great solution if you have a smaller home and are tight for space. Although a system conversion costs extra on top of your boiler installation costs, it is worth considering how much you may save in the long run on your heating bills and how a smaller boiler can benefit your home space. 

On the other hand, if you are on a tight budget or live in a larger house with a high demand for hot water at any one time, then a combi boiler conversion may not be the right option for you.

When Should I Have My Boiler Replaced? 

You can, of course, change your heating system at any time; however, to avoid disruption and upheaval in your home, especially where there are carpets, the ideal time to have your system changed is during a refurbishment, particularly if you currently have a system or heat-only boiler with tanks.

Can My Conventional Boiler Be Converted To A Combi?

Yes, having your conventional boiler converted into a more efficient combi heating system is possible by a qualified engineer.

But first, some due diligence needs to be carried out, combi runs off the mains water supply, so you must first ensure the pressure from your cold tap is sufficient. The specific reason the cold tap is crucial is that often system and heat only boilers have pumps on the showers to increase pressure. If a conventional boiler is converted to a combi boiler, these pumps will be removed along with the hot water tanks many conventional boilers use.

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How Much Does A New Combi Boiler Cost?

As with any appliance, new boiler and installation prices can vary due to several contributing factors including brand, model, merchant and engineer rates. 

In general, the average price for a new combi boiler heating system in 2022 (including installation rates) is in the region of £1975. A good price bracket considering the potential for long-term savings and the high spec and functionality of modern combi boilers.

Getting A New Combi Boiler With iHeat

Here at iHeat we stock a range of sleek, modern combi boilers that are efficient in terms of their performance and ability to free up valuable space in your property.

For a fixed quote on a new combi boiler click here.

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Get a quote in 60 seconds, fitted as fast as next day!
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Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.