Boiler Types

Choosing a boiler

Before you begin the process of researching and possibly purchasing a new boiler it is vital that you fully understand the different types of boilers which are available and which are right for your needs. Our rundown of boiler types will point you in the right direction – but don’t forget that your installer will be able to give you the full details of the model you choose.

Combi Boilers

A combination boiler is by far the most popular type of boiler used in the UK and will provide heating and hot water without the need of a hot water tank. This is a great space saving option as you can remove your cylinder and storage tank. The hot water is unlimited as it is heated as it enters the house.

One drawback is the fact that the water pressure may become reduced if you are using more than one hot water tap at once. The amount of water supplied is between 9 and 18 litres per minute when heated to around 35 degrees Celsius. If you want the water hotter, the water pressure will be lower. For this reason they are best for homes which have only one or two bathrooms or for smaller families.

If you want to have a powerful shower, but also want the smaller combi-boiler, you can run your shower via the bath taps as this will offer better pressure. Electric showers may also be a good option. However if your boiler breaks down, there is no immersion heater, so you have no hot water back up.

System Boilers

These are also known as sealed system boilers and uses a storage cylinder, but no hot water tank. This means you can avoid having a large hot water tank in your loft, but you will need a smaller cylinder in your airing cupboard. Because of this storage facility, you have more hot water on hand for use at the same time without pressure issues.

You may find that you can run out of hot water and will need to wait for it to heat up again and the space taken up by the cylinder can be significant. However it is perfect for a larger home where you have multiple bathrooms. Be careful to ensure you hot water tank is well insulated so that you do not use up energy reheating the water.

This type of boiler can often be more easily installed and is very common, especially in older homes.

Open Vent Boilers

Also known as a conventional boiler, this type have both a hot water tank and a cylinder, allowing you to use plenty of hot water all over the house. Perfect for high pressure showers and where high numbers of people are using the system at the same time. These systems are usually gravity fed although you may be able to use a pump for your shower.

It is still possible for the hot water to run out and you will need to wait for it to reheat and this type of system takes up plenty of space, both in the loft and in your home.

Condensing Boilers

This is more of a sub-type of boiler, as combi boilers and conventional boilers can also be condensing. In fact all new boilers installed in UK homes have to be condensing as they are by far the most efficient type.

A condensing boiler will capture some of the heat which is usually vented to the outside and will reuse it. This makes them around 90% efficient, giving you more for your money. In fact it is estimated that you can save around £300 a year by installing a condensing boiler instead of a conventional one.

Oil Boilers

While there are fewer people who use an oil boiler these days, for those who live in parts of the country where gas is not available, they are an essential item. In some cases these boilers are located outside of the home and are often supplied as a condensing type boiler which offer more energy saving features.

These units are often large and floor-standing and use kerosene or LPG. They are also more expensive to run than a gas boiler. The oil is stored in a tank outside of your home and pumped in as required.

These boilers are available as heat only and combi boilers and work in the same way as gas boilers in terms of water storage.

Back boilers

Back boilers are ideal if you generate most of your heat via a wood stove or fireplace. They are also perfect for homes which do not have access to gas mains. It can supply both hot water and radiator heating.

The back boiler is located behind the source of heat (the fireplace or the stove) and works via a heat exchanger which has a cold water feed at the bottom. The water passes through the heat exchanger and exits as hot water where it feeds to your central heating system.

Clearly this only works in the winter months when the stove or fireplace is being used.

Biomass boilers

This works in a very similar way to a back boiler, however the biomass boiler is usually located separately from the home and is designed to be used all year round. Biomass boilers usually run on wood pellets although any fuel can be burned. You need to have the space to store this fuel as well as somewhere for the boiler itself.

They do require a certain amount of maintenance and need to be cleaned regularly, however they are considered to be very efficient and are thought to be carbon neutral.