Combi Boiler vs System Boiler
Choosing between a combi and system boiler is one of the biggest decisions when replacing your heating system. Both have distinct advantages depending on your home size, hot water demands, and space constraints. This guide will help you make the right choice.
Combi Boiler
A combination boiler provides instant hot water on demand without the need for a separate hot water cylinder or cold water tank. It heats water directly from the mains when you turn on a tap.
Pros
- +No hot water cylinder needed - saves space
- +No cold water tank in loft
- +Instant hot water on demand
- +More energy efficient - only heats water when needed
- +Lower installation costs
- +Simpler system with fewer components
Cons
- −Struggles with multiple outlets at once
- −Not ideal for homes with 2+ bathrooms
- −Flow rate limited by mains pressure
- −No backup if boiler fails
- −Can't work with some power showers
Typical cost: £2,000 - £3,500 installed
Best for: Small to medium homes with 1-2 bathrooms and moderate hot water demand
System Boiler
A system boiler works with a hot water cylinder to store heated water, allowing it to supply multiple outlets simultaneously. The main heating components are built into the boiler, eliminating the need for a loft tank.
Pros
- +Can supply multiple bathrooms simultaneously
- +Compatible with power showers
- +Better for larger homes
- +Hot water stored and ready immediately
- +Works with solar thermal systems
- +More consistent water pressure
Cons
- −Requires space for hot water cylinder
- −Higher installation cost
- −Standing heat losses from cylinder
- −Takes time to reheat cylinder when depleted
- −More complex system
Typical cost: £3,000 - £5,500 installed
Best for: Larger homes with 2+ bathrooms, high hot water demand, or solar thermal compatibility
Side-by-Side Comparison
| Feature | Combi Boiler | System Boiler |
|---|---|---|
| Installation cost | £2,000-£3,500 | £3,000-£5,500 |
| Running costs | Lower | Slightly higher |
| Space needed | Just boiler | Boiler + cylinder |
| Hot water flow rate | Mains limited | Excellent |
| Multiple outlets | Struggles | Handles well |
| Power shower compatible | No | Yes |
| Solar compatible | Limited | Yes |
| Reliability | Good | Good |
Our Expert Recommendation
For most North London homes with 1-2 bathrooms, a quality combi boiler offers the best combination of efficiency, cost, and convenience. However, larger Victorian and Edwardian properties with multiple bathrooms will benefit from a system boiler's ability to deliver hot water to several outlets simultaneously. We assess each property individually and can advise on the best solution for your specific needs.
Choose Combi Boiler if:
Small to medium homes with 1-2 bathrooms and moderate hot water demand
Choose System Boiler if:
Larger homes with 2+ bathrooms, high hot water demand, or solar thermal compatibility
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https://www.hampsteadrenovations.co.uk/ | Email: contact@hampsteadrenovations.co.uk