System boilers explained

photo of a system gas boilerA system boiler directly heats your central heating system as well as hot water for a storage cylinder. They are heat only and work like a regular (conventional) boiler on the principle of stored hot water, however system boilers do have some distinct advantages and disadvantages.

Advantages of system boilers

Easier installation

Installation of a system boiler can be easier, quicker and neater than the installation of other boiler types. This is due to many of the individual components of the heating and hot water system being built into a system boiler. By building in components, the unit is more compact and in many homeowners eyes more attractive.

Great for high hot water demand

A system boiler uses a large tank of stored water meaning you can use multiple taps at one time without a reduction in pressure. This makes it ideal for busy or large households.

Fast and economical

System boilers include a pump, which means it responds quickly and has more economic running costs.

No need for a cold water feed tank

System boilers don’t require a feed and expansion tank, or a cold water feed tank as they can be used with pressurised cylinders. This can save space and still gives you the option of having a system boiler even if you don’t have a loft.

Disadvantages and considerations for system boilers

System boilers can take up more space

Although there is no need for a cold water feed tank, system boilers actually take up more space than combi boilers. This is due to the need for a hot water tank.

The tank needs to be well insulated

The hot water cylinder or tank needs to be well insulated to reduce the amount of heat lost (and energy wasted). This is really more of a consideration than a disadvantage as insulating a hot water tank is cheap and straightforward in most cases.

Hot water tank size

The amount of hot water you can use will be dictated by the size of your tank or cylinder as you will need to wait for more water to be heated once you have used it all.

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