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Updated: June 25, 2024

If a combi boiler meets your home’s hot water and heating needs, transitioning from a conventional boiler to a combi unit is a smart move. Combi boilers offer space-saving advantages with their compact design.

In essence, upgrading from an old boiler to a new one, irrespective of type, enhances heating system efficiency and potentially reduces energy costs. Furthermore, this upgrade enables you to shrink your carbon footprint.

If your home’s hot water and heating needs can be met by a combi boiler, transitioning from a conventional boiler to a combi model is a viable option. Combi boilers offer space-saving advantages thanks to their compact design.

In general, replacing an old boiler with a new one, regardless of type, can enhance heating system efficiency and potentially lower energy bills. Another noteworthy benefit is the opportunity to reduce your carbon footprint.

How much does it cost to replace a regular boiler with a combi boiler?

A new combi boiler typically ranges between £500 and £2,000, with installation costs excluded. The final price hinges on factors such as model, size (output rating), brand, special features, efficiency, and warranty length.

Installation expenses vary based on complexity. Replacing a regular boiler with a combi entails several tasks, making it one of the costliest and most intricate replacements. This process involves removing the cold water feed tank, hot water cylinder, and reconfiguring pipework setup.

Why replace your regular boiler with a combi boiler?

  • To improve the efficiency of your home by 30%
  • To reduce your energy bills. A combi boiler is very efficient
  • To improve safety and prevent gas leak. 
  • To reduce your carbon footprint 
  • To increase the value of your property 

New condensing boilers are more fuel-efficient compared to old boilers, leading to reduced energy bills and cost savings. Additionally, replacing a regular boiler with a combi offers space-saving benefits and instant hot water.

Combi boilers, renowned for their compact size, can fit inside a standard kitchen cupboard. They draw water directly from the mains, heating it on demand and eliminating the need for a cold water feed tank and hot water cylinder.

Unlike conventional boilers, which require waiting for the hot water cylinder to refill, combi boilers instantly heat water from the mains, supplying it to showers and taps.

While combi boilers are ideal for homes with one bathroom, they may struggle to supply hot water to multiple showers simultaneously. However, certain combi boiler types can handle high hot water demand for two bathrooms.

For homes with multiple bathrooms, a storage combi boiler is a viable option. Operating similarly to a combi boiler but with a hot water cylinder for storage, these boilers offer a blend of combi and system boiler features.

Read about: Common Boiler Issues and How to Fix Them

What are the advantages of combi boilers?

Advantages of Combi Boilers:

Hot Water on Demand: Combi boilers excel in providing instant hot water, unlike system boilers which need to heat and store water beforehand.

Efficiency: Combi boilers boast high efficiency rates, typically over 92%. This translates to lower energy bills and a reduced carbon footprint.

Compact Size: Ideal for space-constrained homes, combi boilers are compact and can be conveniently installed even in kitchen cupboards.

Easy Installation: Installation is straightforward as combi boilers eliminate the need for a cold water tank or hot water cylinder, saving both time and money.

Read about:

System Boiler Replacement

Replacing a regular boiler with a combi boiler 

Find the Best Boiler for your home 

Best combi boilers & boiler brands

Signs of an Old Boiler:

Slow Heating: Radiators taking longer to heat up than usual could indicate an aging boiler, which may struggle to efficiently heat your home.

Increased Energy Bills: Decreased efficiency in older boilers can lead to higher energy costs over time.

Strange Smells: A sulphurous or eggy smell from the boiler might signal a gas leak or combustion issue, requiring immediate attention.

Unusual Noises: Humming, banging, or vibrating sounds from radiators or the boiler itself could suggest internal damage or blocked pipes.

Changes in Pilot Light Color: A yellow instead of blue pilot light or dark stains on the boiler may indicate a potential carbon monoxide leak, posing serious safety risks.

Difficulty Finding Replacement Parts: Obsolescence of parts indicates the boiler is outdated, making repairs and maintenance challenging.

Persistent Leaks: Constant leaks are another indication of an aging boiler in need of replacement or repair.

Read more about:

best boilers in uk

Step by step guide to boiler installation

Viessmann Boilers Review


Are combi boilers cheaper to run than conventional boilers?

The running cost of a boiler depends on its output rating and efficiency rather than the type of boiler in question. In short, the higher the efficiency of your boiler is, the cheaper to run it is. 

Is a combi boiler very efficient?

Combi boilers are very efficient. They can show 92%-98% efficiency.

Do combi boilers use gas or oil?

Combi boilers can use different types of fuel. They can run on gas, oil, LPG (Liquified Petroleum Gas), and electricity.

Can I change from a regular boiler to a combi boiler?

Yes, it is possible to change your regular boiler with another type. You would just need to know your home’s heating and hot water demand in order to choose the right boiler.