PRACTICAL GUIDE · UPDATED 2026-10-30
Choosing your heating: combi, system, regular or heat pump?
Compare hot-water arrangements, space and the questions a proper home survey should answer.
| Option | Hot water & space | Ask the installer |
|---|---|---|
| Combi boiler | On-demand tap water; normally no separate cylinder. | Will mains flow and boiler output support our simultaneous use? |
| System boiler | Stored hot water in a separate cylinder. | How much usable hot water and what reheating time? |
| Regular / heat-only boiler | Cylinder; traditional systems may also have loft tanks. | What existing tanks and pipework would remain or change? |
| Air-to-water heat pump | Outdoor unit and usually a compatible cylinder. | What heat loss, radiator changes, seasonal performance and siting checks? |
Start with the home: how many people use hot water together, where equipment could go, and what needs improving? Ask the installer to explain the existing system before suggesting a replacement. Keep your comfort, carbon goals and full budget in the same brief.
A combi heats tap water on demand. System and regular boilers usually use a hot-water cylinder; traditional regular systems can also have loft tanks. Air-to-water heat pumps normally use a suitable cylinder for hot water. Cylinder space, incoming water supply and simultaneous showers all need assessment.
Compare complete installed options, including controls, radiators, cylinder, pipework, electrical work, removal and commissioning. Ask for room-by-room heat-loss calculations, the proposed design temperatures and a written running-cost comparison using your tariffs. A heat pump can reduce operational emissions, but its bills depend on seasonal performance and electricity prices. No system label alone guarantees savings.
Your checklist
- Compare two designs against the same household needs.
- Ask why this type and size suit the property.
- Check the named engineer’s relevant Gas Safe categories for gas work.
- Keep commissioning, controls training and servicing in the written scope.
Sources & further reading
- Energy Saving Trust: Boiler types ↗
- Energy Saving Trust: Air source heat pumps ↗
- HSE: Check a Gas Safe engineer ↗
General information, not a property assessment, booking or assurance about a listed business. Dates indicate content updates; they are not invented publication dates.