When a boiler needs replacing, the first question is usually which type. Most homes in the UK have one of three: a combi, a system boiler or a regular boiler. Each one suits a different kind of home.
Here is how each works, who it suits and what Gary looks at before recommending one.
Combi boilers
A combi, short for combination boiler, heats water for your taps on demand and runs the central heating, all from one unit. The Energy Saving Trust explains that combi boilers do not use a hot water cylinder. All the heat and hot water comes from the boiler itself.
Good for: flats and smaller homes, households with one bathroom, and anyone short on space. There is no cylinder to find room for and no tanks in the loft.
Less suited to: homes with several bathrooms or more than one shower used at the same time, and homes with low mains water pressure. The Energy Saving Trust notes that combis suit smaller households better for this reason.
System boilers
A system boiler heats the central heating directly and stores hot water in a separate cylinder. The Energy Saving Trust says system boilers suit larger households, because the stored hot water can serve several taps at once.
The cylinder can be a vented one fed from a tank, or an unvented one that runs at mains pressure. An unvented cylinder gives you strong showers without a pump or a tank in the loft. Unvented cylinder work has to be done by someone holding the G3 qualification, which Gary has. Read more about unvented cylinders and hot water.
Good for: family homes with two or more bathrooms, and homes where several people want hot water at the same time.
Less suited to: homes with no space for a cylinder.
Regular boilers
Regular boilers, also called conventional or heat-only boilers, work in a similar way to system boilers but need a cold water storage tank and a feed and expansion tank, usually in the loft. The Energy Saving Trust says they can suit larger properties or homes with low water pressure, but they need more space and are unlikely to suit a flat.
Good for: older homes already set up with tanks and a cylinder, where changing the whole system would mean a lot of extra work.
Less suited to: homes where loft or cupboard space is needed for other things.
What decides it
There is no one best boiler type. The right answer depends on the house and the people in it. Gary looks at:
- Hot water demand. How many bathrooms, how many people, and whether showers run at the same time
- Mains water pressure and flow. A combi and an unvented cylinder both depend on a good mains supply
- Space. Whether there is room for a cylinder, and whether you want the airing cupboard or loft back
- The existing system. The radiators, pipework and gas supply, and whether changing type is worth the extra work
- Budget. Keeping the same type is usually simpler than switching
Thinking of switching?
Switching from a regular boiler to a combi is common when a household gets smaller or wants the space back. It means removing the loft tanks and cylinder, and checking the mains supply can cope. Going the other way, from a combi to a system boiler with a cylinder, is common when a family grows or adds a second bathroom.
Either change is more work than a like-for-like swap, so it is worth getting it right first time. If you are weighing up whether your current boiler is worth keeping at all, our guide on repairing or replacing an old boiler may help.
Get honest advice
Gary will look at what you have and talk through what suits your home, rather than pushing whatever is easiest to fit. See boiler installations and replacements for what is included.
He covers Gloucester, Stroud, Cheltenham and nearby. Quotes are free. Call 07454 117678 or get in touch.