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Combi vs System Boiler: Which Is Right for Your Home?
Two very different ways to heat your home and hot water. Here is how to choose between a combi and a system boiler — without the jargon.
James Carter
Senior Heating Engineer24 Jun 2026Updated: 24 Jun 20265 min read
Key takeaways
Reading time — 5 min
Expert reviewed — Practical guidance from our heating team
When your old boiler reaches the end of its life, the first question is not which brand to buy — it is which type of boiler suits your home. For most households the real choice is between a combi and a system boiler.
Choose a combi if…
- Space is tight — no cylinder or tanks means a tidy, compact install.
- You have one bathroom and want excellent pressure on demand.
- You want the lowest upfront cost with fewer parts and less pipework.
Choose a system boiler if…
- You have two or more bathrooms that may run at once.
- Your mains pressure is modest and stored hot water suits you better.
- You are planning solar or a heat pump that a cylinder integrates with.
The five-minute decision
Count your bathrooms, check your mains pressure, and picture where a cylinder would live. One bathroom plus good pressure points at a combi; two or more bathrooms points at a system boiler. A free survey settles it precisely.