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Pros and cons of a combi boiler: What they are and how they work?

The combination boiler gets its name because it is a combination of both a high-efficiency water heater and a central heating boiler system in one compact unit. Hot water is heated on demand as soon as you turn a hot water tap or shower on, so there’s no need for a storage tank as you would need with a conventional or system boiler.

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Simply answer a few multiple choice questions about your existing boiler and we’ll give you a fixed price for a new boiler including all parts and installation[28]

How does a combi boiler work?

Combi boilers usually have two independent heat exchangers; one of which carries a pipe through to the radiators, while the other carries a similar pipe through to the hot water supply. When you turn a hot tap on, your boiler fires up to heat water and a valve is opened to send the water out through a network of pipes. A combi boiler will usually need to pause from heating the central heating water for your radiators while it’s heating the hot water for your tap, because they often can’t supply enough heat to supply to both at the same time. For this reason, you might hear your boiler switching on and off when you run a hot water tap even if they’re already lit to power the central heating.

How are combi boilers fuelled?

In the UK, gas is commonly used to fuel combi boilers because most domestic properties have access to gas mains through an underground network of pipes. Therefore, you’ll find a wider choice of combi boilers fuelled by gas than any other fuel type. However, combi boilers can also be fuelled by LPG or oil if you’re in a rural area where you haven’t access to gas. LPG is supplied in bottles which will regularly need replacing. Similarly, oil is stored in a tank which will require re-filling.

Pros of combi boilers:

Cons of combi boilers:

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[28] Exclusions apply. See