Replace your boiler in a day. Cut your heating bill overnight.

Name: Hestora Thermal Energy Store
Brand: Hestora

How it works

Three things happen. You just enjoy the savings.

Hestora manages everything in the background. All you notice is the same warm home and a lower bill.

Charges overnight

From midnight, Hestora fills up on cheap off-peak electricity, automatically finding the cheapest window so you don't have to.

Water is heated to up to 175°C inside a pressurised vessel rated to PD 5500:2024+A2 (Category 2), independently tested to 17.86 bar by British Engineering Services, over double its 8 bar operating pressure. Round-trip efficiency ~90% measured; standing loss ~4 kWh/day, largely recovered as useful space heat.

Delivers on demand

Stored heat flows to your radiators and hot water taps when you need it, just like a boiler, but the energy was bought overnight when it was cheap.

Heat exchangers deliver mains-pressure domestic hot water and feed a conventional wet central-heating circuit. No emitter upgrades, no new pipework, no outdoor unit. The vessel arrives light and is filled with water on-site, installed in a single day.

Earns on the grid

From cheap overnight power to surges in daytime solar and wind, Hestora charges whenever energy is cheapest or greenest.

NESO's Demand Flexibility Service pays controllable demand assets to absorb surplus renewable electricity. Each Hestora unit can absorb 40 kWh on instruction.

Why Hestora

A different bill. The same warm home.

A simple boiler replacement that cuts your bills, fits your existing home, and shrinks your carbon footprint.

Lower bills

Smart charging automatically uses low-cost, off-peak electricity. Optimised heating and high-grade insulation cut losses and deliver savings.

Simple retrofit

Replace your gas boiler with Hestora. Done. No major fabric upgrades. It is designed for the home you already have and the same high flow temperatures.

Lower carbon

Zero emissions in your home, and it supports a decarbonised grid by shifting demand away from peak times, powered by renewables.

Specification

Rigorously tested. Engineered to British standards.

UKCA certified & pressure-tested.Independently tested to 17.86 bar (2× operating pressure) by a leading UK engineering body.

High-performance insulationBuilt to retain heat with a measured 90% round-trip efficiency

High-capacity heat storage.Stores up to 40 kWh of thermal energy to cover your peak heating and hot water needs.

Boiler-level flow temperatures.Delivers the same high temperatures your radiators expect.

Stage 1 of 5

The pressure vessel

A welded steel vessel certified to PD 5500:2024+A2 (Category 2), independently tested to 17.86 bar: more than double its 8 bar operating pressure.

Energy capacity	40 kWh
Heat output	30 kW
Operating temperature	50–175°C
Operating pressure	0–8 bar g
Vessel certification	PD 5500:2024+A2 Category 2 · tested to 17.86 bar g by British Engineering Services
Round-trip efficiency	~90% measured
Design life	>30 years
Storage medium	Water: non-toxic, non-degrading, no cycling degradation
Installation	Light dry weight · filled on-site · one-day swap in existing boiler/cylinder footprint
Hot water	Mains-pressure DHW via heat exchanger
Space heating	Conventional wet central-heating circuit · no emitter upgrades required
Grid integration	Smart time-of-use tariff optimisation

Common questions

Things people always ask.

Hestora has a compact 660 mm × 660 mm footprint—similar to a typical white good or hot water cylinder. It arrives lightweight and is filled with water on-site, making it easy to move through hallways and up stairs. It is suitable for houses, bungalows and maisonettes with a wet central heating system.

It’s built to strict UK engineering standards and independently tested by British Engineering Services. They tested the pressure tank at more than double its maximum daily working pressure, so you can be completely confident in its safety and build quality.

Commercial sales are planned to begin in 2027. The final customer cost will depend on available funding, including the £2,500 Boiler Upgrade Grant and approximately £1,000 in carbon-offset funding. A monitored pilot involving more than 20 homes will begin in November 2026. Register your interest below to be among the first in the queue.

Heat pumps are excellent for homes that suit them. Hestora is designed for homes where heat pumps are impractical: no outdoor space, existing radiators, tight access, or a tighter budget. Both reduce gas use; they suit different homes.

No. Hestora connects to your existing wet central heating system: same radiators, same pipework, delivering the same high flow temperatures your boiler used to.

I'm an installer — how do I get involved?

We’d love to work with you! Simply leave your details below, and a member of our team will reach out for a chat about joining our installer network.

No. Hestora works with whatever heat emitters you already have: radiators or underfloor heating. If your home has underfloor heating, Hestora delivers heat at the lower flow temperatures that system needs, just as it does for radiators. You don't need to install underfloor heating to benefit from Hestora, and you don't need to remove it if you already have it.

The Boiler Upgrade Scheme (BUS) grant is expected to apply to all qualifying thermal energy stores, including Hestora. The relevant BSI performance standard and MCS design and installation standard are currently progressing through approval, which we hope will be completed by October 2026. We will keep everyone who registers updated as further details are confirmed.

Initially, Hestora will charge during the fixed off-peak window offered by major energy suppliers, so you will need a suitable off-peak electricity tariff. Developments planned for 2027 will introduce smart, grid-responsive charging, enabling Hestora to charge when electricity is abundant and potentially earn rewards through NESO’s Demand Flexibility Service, including demand turn-up events.

Our initial focus is on houses, bungalows, and maisonettes with individual heating systems. We’re actively planning for flats and properties with shared heating systems in upcoming product phases—register your interest below, and we’ll be sure to reach out as soon as we expand!

Yes, Hestora requires a hot water cylinder to run. It connects straight into your current system to heat both your radiators and your water. If your home currently has a combi setup without a cylinder, a new one will be added during installation.

I don't own my home.

Absolutely! We know renting can make upgrade decisions tricky, but we’re here to help. Get in touch with us and we can reach out to your landlord directly on your behalf, or we can send you some info to share with them yourself.

Backed by

Working with the people who know this best.

Tap or hover any logo to see how each partner works with Hestora.

Imperial College LondonClimate Innovation Platform accelerator partner. Technical mentorship, lab access and route-to-market support.

University of BirminghamAcademic partner on the Climate Innovation Platform, contributing materials science and thermal storage research.

Energy Systems CatapultProviding guidance through their business accelerator, the Climate Innovation Platform which is run jointly with the University of Birmingham.

Climate Innovation PlatformA business accelerator program transforming the West Midlands into a powerhouse of energy technology innovation. Hestora is a member of the 5th cohort.

Royal InstitutionCo-lead institution delivering Undaunted's business accelerator ecosystem for climate innovators.

UndauntedUndaunted powers exciting early-stage climate innovation across London, the UK and beyond. Hestora is a member of the Greenhouse's 10th cohort.

ElmaticElectrical and controls engineering partner, supporting the design of Hestora's control electronics and switchgear.

LTI MetaltechPrecision metal fabrication partner for the pressure vessel and structural components of the Hestora unit.

SWEPTemperature engineering partner, supplying precision heating elements used in the Hestora thermal core.

BigBear Plastic ProductsManufacturing partner supplying moulded plastic components for the Hestora unit housing and fittings.

All Valves OnlineValve and flow-control component supplier, providing certified hardware for Hestora's plumbing and safety systems.

AVA ActuatorsSmart actuator technology partner, supplying the precision actuators that control charge and discharge flow.

Etex GroupInsulation materials partner, supplying the high-performance insulation that keeps standing losses low.

Industrial Trading SolutionsIndustrial supply and distribution partner, sourcing certified components and fittings for the Hestora unit from UK manufacturers.