Combi, system or regular? Each type works differently and suits different homes. Here’s a side-by-side look at how they compare, so you can see which fits your household.
Combi boilers
A combination boiler provides both heating and hot water from a single unit, heating water on demand directly from the mains. There’s no hot-water cylinder and no cold-water tank in the loft.
- Best for: flats and small-to-medium homes with one bathroom.
- Pros: compact, efficient, no stored-water heat loss, strong mains-pressure hot water, quick to install.
- Cons: flow can drop if two outlets run at once; relies on good mains pressure.
System boilers
A system boiler heats a separate hot-water cylinder. Most components are built into the boiler, so there’s no loft tank, but you do need space for the cylinder.
- Best for: family homes with two or more bathrooms and higher demand.
- Pros: supplies several outlets at once, consistent pressure, works well with renewables.
- Cons: needs cylinder space; a finite store of hot water that reheats after heavy use.
Regular (conventional) boilers
A regular boiler uses a hot-water cylinder plus a cold-water feed and expansion tank, usually in the loft. It’s the traditional setup found in many older homes.
- Best for: older properties with existing conventional systems, or homes with very high demand or low mains pressure.
- Pros: excellent for high hot-water demand; often the simplest like-for-like replacement.
- Cons: takes up the most space; more components to maintain.
Quick comparison
| Feature | Combi | System | Regular |
|---|---|---|---|
| Hot-water cylinder | No | Yes | Yes |
| Loft tank | No | No | Yes |
| Multiple bathrooms | Limited | Good | Excellent |
| Space needed | Least | Moderate | Most |
Which should you choose?
If space and efficiency matter most and you have one bathroom, a combi is usually ideal. For a busy household with several bathrooms, a system boiler keeps up with demand. If you have a traditional high-demand setup, a regular boiler may be the practical choice. We’ll help you decide, request a free quote.