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Combi Boiler: Pro’s & Con’s

What is a combi boiler?

Combi boilers are the UK’s most popular type of boiler, mainly because they provide hot water and central heating combined in one unit – hence the name. Hot water is offered on-demand and heating is typically energy-efficient, so they are generally seen as convenient and energy-saving.

Combination boilers are also manufactured to be compact as there’s no need for a water tank or cylinder. In many cases, your combi boilercould be fitted into a kitchen cupboard, so they could be ideal for homes with limited space.

How does a combi boiler work?

When you turn the hot-water tap on in your home, the combi boiler will kick into action. On its way from the mains to your tap, the water will pass over a sensor which tells the boiler to burn fuel (gas or oil). A heat exchanger, inside the combi boiler, then gets hot so that when the water flows over it, it gets hot before it reaches the tap.

The boiler’s heating function works in a similar way, providing your radiators with hot-water.


Combi boilers – pros and cons

Combi boilers are becoming increasingly common in homes around the UK; this is likely to be a result of the many advantages that they typically provide. These boilers may not be appropriate for every home nevertheless, so it’s usually best to seek the advice of a qualified Gas Safe registered engineer. Here’s a list detailing what we believe to be the pros and cons of combi boilers:


Advantages of a combi boiler

Designed to be compact in size - Combi boilers are good for smaller properties, especially where there is no loft or very little space in the loft. Consequently, there is no concern about freezing loft pipework. You could even put the combi boiler in an existing cupboard – neat and out of the way.

A potentially cost-effective option - As there is less pipework to put in, installation could be cheaper. Also, because the combi boiler only heats the water you need, less energy could be wasted which could lead to lower energy bills*.

Typically convenient - Hot-water is delivered on-demand with combi boilers, which could be very convenient if you want to jump in the shower. In addition, because the hot-water comes out at mains pressure, there is no need for an additional pump.

Designed to improve energy-efficiency - As stated previously, combi boilers are typically highly energy-efficient. This is increased when paired with additional energy-saving tools such as a smart thermostat. When your central heating is paired with such technology, your control over the heating in your home could be enhanced and you could even gain the ability to control your home heating whilst on the go!


Disadvantages of a combi boiler

Not particularly well suited to homes with high hot-water demands - Because combi boilers provide hot water on demand, you might find that they don’t work well if more than one hot tap is turned on at once. If you have a family who all want to shower in the morning, for example, you might find that a combi boiler might not deal well with this. There are alternatives, though, such as having an electric shower, or even a mains booster or accumulator tank.

No Immersion Heater - Immersion heaters are often fitted with conventional boilers to provide a back-up in case your boiler breaks down. Unfortunately, combi boilers cannot be fitted with these back-up water heaters, so in the event of a breakdown you may be left without heating and hot-water until your repair appointment.

Which combi boiler?

If you’re unsure about which combi boiler could be a suitable choice for your home, our free online quote tool could provide you with the information you need. Simply answer a few questions about you home and central heating demands and within a few moments you could receive your free quote.

If you're having problems, HomeServe do a range of one off repairs including plumbing, gas, boiler or electrical. HomeServe have experienced engineers who are Gas Safe registered.


* Source: Saving calculated when replacing G rated with A rated boiler in a semi-detached house.

Information and other materials on this website are not intended to constitute professional advice and should not be relied upon. Please see our Terms of Use for further details.

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