New Boiler Installation: Combi vs System 2026

Boiler types compared

A combi boiler heats water on demand with no cylinder, saving space and suiting most small to medium homes. A system boiler works with a hot water cylinder to serve larger homes and several bathrooms at once. A regular (heat-only) boiler uses a cylinder and a cold-water tank, common in older houses. An air source heat pump is the low-carbon alternative, running the heating at lower temperatures.

New boiler cost 2026

In 2026 a straight combi swap typically costs £2,000–£3,500 installed, a system boiler £2,500–£4,000, and converting between types or relocating the boiler adds more for pipework. An air source heat pump costs roughly £8,000–£14,000 before the Boiler Upgrade Scheme grant of £7,500, which brings the net cost down significantly.

Should you consider a heat pump?

A heat pump makes most sense in a reasonably well-insulated home with room for the outdoor unit and, ideally, slightly larger radiators or underfloor heating. It cuts carbon and can qualify for the £7,500 grant, but the upfront cost is higher and running costs depend on your electricity tariff. For many homes a modern condensing boiler is still the simplest upgrade.

How to choose and compare quotes

1. Match the boiler to your home

Count your bathrooms and hot-water demand — combi for smaller homes, system for larger ones with a cylinder.

2. Use a Gas Safe engineer

Always use a Gas Safe registered engineer for a boiler, or an MCS-certified installer for a heat pump.

3. Consider efficiency and controls

A high-efficiency boiler with smart controls and thermostatic valves cuts running costs over its life.

4. Get three like-for-like quotes

Compare on the same boiler type, output and controls so you judge value, not just headline price.

FAQs

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