How it works
- How heat pumps workThe refrigerant cycle, one step at a time
- Types of heat pumpAir, ground, water, air-to-air and hybrid
- Air source vs ground sourceThe two main choices side by side
- Hybrid systemsA heat pump sharing with a boiler
- Flow temperatureThe setting that decides efficiency
- Hot waterCylinders, reheat and the hygiene cycle
Efficiency
Costs and your home
What these guides leave out
This site explains how heat pumps work and how to think about them. It does not walk through an installation, check installers, go deep into grant eligibility or cover particular towns; other sources do those jobs better. Where a guide touches a grant, it says only what changes how a system is chosen, with a link to GOV.UK for the rules.
Every figure in the guides comes from a named source, listed at the foot of each page and gathered on the sources page. If a figure has changed since the page was checked, the source is the one to trust.
Three ways through the guides
- "How does it work?" How heat pumps work, then the types, then cold weather.
- "Will it cost more than gas?" COP, SCOP and SPF, then flow temperature, then the cost per kWh of heat calculator and the tariffs guide.
- "Would it suit my home?" Is my home suitable, then hot water, then noise, then hybrids if a full system looks like too much work.
How the guides are written
Each guide answers one question, starts with the answer in a line, defines its terms in the side panel and ends with its sources. Figures are given with the date they were read, and calculations are shown so they can be repeated with other numbers.