System Boilers
Stored hot water for larger homes. Multiple taps at once. A newer system boiler costs around £3,000 fitted (Checkatrade guide)
What is a System Boiler?
A system boiler heats water and stores it in a hot water cylinder, so you always have a ready supply of hot water for multiple taps and showers simultaneously. Unlike combi boilers, system boilers can supply several bathrooms at once without losing pressure or temperature.
System boilers have most components built-in (pump, expansion vessel, pressure gauge), making installation simpler than traditional regular boilers. They're well suited to larger homes with 2+ bathrooms and high hot water demand. How strong the flow is depends on your cylinder and water supply, which your installer will check.
System Boiler Benefits
Multiple Taps
Supply 2+ bathrooms simultaneously without pressure drop
Good Flow to Several Outlets
Stored hot water can serve more than one shower at a time
Choice of Cylinder
Works with a mains-pressure (unvented) or tank-fed (vented) cylinder - your installer will advise which suits your supply
Large Hot Water Store
Cylinder sized to how much hot water your household uses
Solar Compatible
Can work with solar thermal panels to preheat water (needs a suitable cylinder)
Efficient
Modern condensing, A-rated models available
System Boiler Costs
+ Hot Water Cylinder Cost
If you don't already have a suitable cylinder, a new one adds to the price - ask for it to be itemised in your quote
No Grant for Most Boiler Swaps
The Boiler Upgrade Scheme does not fund gas boilers. ECO4 (until 31 December 2026) can sometimes include a broken-boiler replacement where strict rules are met, but a boiler is not guaranteed. UK Energy Partnership is run by Harber Glaves Trading Ltd, not a government body.
Is a System Boiler Right for You?
✓ Perfect For:
- • Larger homes with 2+ bathrooms
- • High hot water demand (multiple showers at once)
- • Homes with power showers or large bath
- • Properties with existing hot water cylinder
- • Homes planning to add solar thermal panels
⚠ Consider Combi Boiler If:
- • Small home with 1 bathroom
- • Limited space (no room for cylinder)
- • Good mains water pressure
- • Lower upfront cost is priority
System vs Combi vs Regular
| Feature | System | Combi | Regular |
|---|---|---|---|
| Multiple taps | ✓ Excellent | △ Limited | ✓ Excellent |
| Space required | Cylinder only | ✓ Minimal | ✗ Tanks + cylinder |
| Low mains pressure | △ Depends on cylinder | ✗ Poor | ✓ Works well |
| Typical cost (like-for-like) | Around £3,000 | £2,500-£4,000 | Around £3,000 |
Supply and installation. Checkatrade new boiler cost guide (March 2026), a guide only; changing boiler type costs more.
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