Boiler guide
Three main types of gas boiler are installed in UK homes. Here's how they differ, and how to decide.
Heats water on demand directly from the mains — no hot water cylinder or loft tanks.
Flats and small-to-medium homes with one main bathroom.
Heats a stored cylinder of hot water. Key components are built in, with no loft tanks.
Larger homes with two or more bathrooms used at the same time.
Works with a cold water tank in the loft and a hot water cylinder — a traditional setup.
Older homes with existing tanks and pipework that suits gravity-fed systems.
A rough starting point only — the final recommendation should come after looking at your actual home.
| If your home has… | Combi | System | Regular |
|---|---|---|---|
| One main bathroom | Often suits | — | — |
| Two or more bathrooms used together | — | Often suits | — |
| Limited cupboard/loft space | Often suits | — | — |
| Low mains water pressure | — | — | Often suits |
| Want to keep options open for solar or heat pump | — | Often suits | — |
| Older home with existing loft tanks | — | — | Often suits |
Combi and unvented system setups rely on your mains supply. If flow is weak, performance suffers. A simple flow test during the survey tells us what your supply can handle.
Combi outputs are mostly about hot water flow rate; system and regular outputs are about heating demand. Bigger isn't automatically better.
A modern programmable or smart thermostat can help you heat your home only when you need to. We'll talk through options that suit how you live.
If you're considering a heat pump in future, keeping a hot water cylinder (system boiler) can make that transition simpler.
Still not sure? Start a quote and choose "Not sure" — we'll advise.
Answer a few questions about your home. It takes about two minutes, and there's no obligation.