An electric boiler supplies heat to a wet system when demand occurs. A heat battery stores energy beforehand. Both can use resistance electricity, but storage may move consumption into a cheaper period.
The short answer
An electric boiler avoids sizing a large energy store but exposes heating demand to the tariff at the time it occurs. A heat battery needs enough capacity and charge time, but may reduce peak-rate consumption.
Power versus energy
The boiler needs sufficient kW to meet current heat loss. The battery needs both discharge power and enough kWh to last until the next charge.
Electrical supply
Either system can be a large load. Storage may concentrate charging into a short window; an electric boiler may run through the day. Assess maximum demand with other appliances.
Controls and depleted storage
Ask what happens when the battery is empty. A direct electric top-up can turn the system into peak-rate electric heating at the least favourable time.
Heat pump alternative
A heat pump can deliver more heat per input kWh than direct resistance heating under suitable conditions. Include it as a separate system option rather than assuming every electric appliance has the same running cost.
Installation scope
Both can use wet emitters, but temperatures, flow rates, buffers and controls differ. Existing radiators still need output checks.
Your next step
Price a cold-week demand profile on the proposed tariff for both systems. Show peak-rate top-up explicitly rather than averaging it away.
Sources
Primary and independent references checked by our editorial team.
- Energy storage options explained — Energy Saving Trust Checked 10 Nov 2026
- Energy price cap unit rates and standing charges — Ofgem Checked 10 Nov 2026