A combi boiler suits most homes with one bathroom and good mains water pressure: it heats water on demand, so there is no hot water cylinder or tank. A system boiler with an unvented cylinder suits homes with two or more bathrooms used at the same time. A regular (heat-only) boiler is mainly for older homes with tanks in the loft, where a change would mean big alterations.
Combi boilers
Heats hot water straight from the mains when you turn on a tap. Compact, frees up the airing cupboard and there’s no waiting for a tank to heat. The downside: running two showers at once can drop the flow, and it relies on decent mains pressure.
System boilers
Heats a stored cylinder of hot water, usually an unvented cylinder fed from the mains. Good for busier homes with more than one bathroom, as several taps can run at once. You need space for the cylinder.
Regular (heat-only) boilers
Work with a cold water tank in the loft and a hot water cylinder. Common in older homes. They suit homes with low mains pressure, but take up the most space.
How to choose
- One bathroom, decent mains pressure? A combi is usually best.
- Two or more bathrooms, used at the same time? A system boiler with a cylinder.
- Old tanks in the loft and low pressure? Sometimes a regular boiler is still the right answer.
We check your water pressure and flow, and talk through how your household uses hot water, before recommending one. Read when to replace a boiler too.
Covering Faversham, Canterbury, Whitstable, Herne Bay, Thanet, Sandwich, Deal and Dover: see areas we cover.
Get it sorted
Call or WhatsApp Addisons Plumbing & Heating with a quick description or a photo, and we’ll tell you what it looks like and arrange a visit. Free, no-obligation quotes across East Kent. If you ever smell gas, call the National Gas Emergency number on 0800 111 999.
Quick questions
Can I switch from a cylinder to a combi?
Often, yes. It is one of our most common jobs. We will check the mains pressure and flow first, because a combi depends on it.
Which boiler is most efficient?
All new gas boilers are condensing and highly efficient. The best choice is the one that matches your home, so it isn’t oversized or struggling.
How big a boiler do I need?
It depends on the size of the home, the number of radiators and bathrooms, and the type of boiler. We size it properly rather than guessing.
