Hot-water systems
Where your hot water comes from.
Your hot-water system decides how much hot water you have, at what pressure, and which showers and taps will work well.
- Mains pressure, on demand
- Combi
- Mains pressure, stored
- Unvented cylinder
- Low pressure
- Gravity-fed
- Low carbon
- Heat pump
The basics
If you're not sure which you have: no hot-water cylinder usually means a combi; a cylinder plus a cold tank in the loft usually means gravity-fed; a cylinder with no loft tank usually means unvented.
In this section 4 pages
Combi boiler
Heats water on demand from the mains, with no tank or cylinder.
System boiler and unvented cylinder
Stores hot water at mains pressure for strong flow to several outlets.
Gravity-fed system
A cold tank in the loft feeds a hot cylinder; pressure depends on the tank's height.
Heat pump
Heats a stored cylinder of hot water, so plan space for it.
Not sure what system you have?
Tell us about your room and what matters most, and we'll help you make the most of it.
Start your project briefIllustrations are concepts, not measured plans. Click any picture to enlarge it.