Heat battery makers in the UK: how to compare them

UK shoppers will encounter several products described as heat batteries or thermal storage, but they do not all perform the same job. Some focus on compact hot water; others store heat for a whole wet central-heating system.

The short answer

Build a shortlist by system role before comparing brands. We are not publishing a “best” table until current UK availability, specifications and source documents have been verified for each maker.

Our comparison criteria

1. System role: hot water, space heating, or both.
2. Storage method: phase-change material, solid core or another medium.
3. Charge sources: direct electricity, heat pump, solar or boiler connection.
4. Useful output: capacity, power, temperature and duration under stated conditions.
5. Installation: electrical load, pipework, weight, space and controls.
6. Support: installer network, warranty route, spares and service access.

Names you may encounter

Sunamp markets phase-change thermal batteries for hot water and other heat uses. tepeo and Caldera are also associated with heat-storage products in the UK, but current domestic availability and product scope must be checked directly before we describe or compare their specifications.

That caution is deliberate. A discontinued model, pilot product or installer-only offering is not a useful recommendation to a homeowner.

Read the test boundary

“Equivalent litres”, maximum flow and storage capacity can be measured under different starting temperatures and draw profiles. Comparable numbers need comparable conditions.

Check the company behind the box

Ask who provides the warranty, who can service the unit, and what happens if the original installer stops trading. Keep copies of commissioning records and control settings.

Your next step

Send the same one-page household brief to each maker or installer. Require each answer to state the model, assumptions and source document. That makes missing evidence obvious.