What is the tepeo ZEB heat battery boiler?

It is a heat-only boiler. The ZEB replaces the central heating side of an existing system and connects directly to existing pipework, but it does not make hot water on demand, so a separate cylinder or heat-storage solution is required⁴. tepeo states that the ZEB is not currently supported by the Boiler Upgrade Scheme, and that heat batteries are expected to be included from winter 2026 with a £2,500 grant once standards and scheme rules are in place⁶.

For a household, the appeal is straightforward: electric heating that behaves like the boiler it replaces, charged when electricity is cheapest, with no gas connection and no flue. The dependence that remains is on the electricity grid, a supplier and a suitable time-of-use tariff, plus a manufacturer whose smart charging and support sit behind the product.

A heat battery boiler: charges like a battery, heats like a boiler

The phrase tepeo uses for the ZEB is that it "charges like a battery" and "heats like a boiler"¹¹. That is a description of behaviour rather than chemistry. There is no electrochemical cell in the appliance. Instead, electricity heats a ceramic core, the heat is held in that mass, and it is released into the central heating water when the home calls for warmth¹. tepeo describes the result as a more familiar boiler-like heating experience, aimed at households that want electric heating without the changes in emitter size and flow temperature that a heat pump often requires¹².

The practical difference from a conventional storage heater is the delivery route. A storage heater releases heat into the room it stands in. The ZEB releases stored heat through a suitable wet central heating system, so the heat arrives at radiators or underfloor heating rather than from a box on the wall¹³. That is what makes it a replacement for a boiler rather than a replacement for a heater, and it is why the unit is sized and sited like a boiler rather than like a night storage unit.

For energy independence, the distinction matters. A gas boiler ties a household to the gas network and to whatever the wholesale gas price does. The ZEB ties the household to electricity, which can increasingly be bought at times of day when it is cheap and, in principle, generated at home. What it does not do is remove the connection to the grid or to a supplier. The ZEB is a load-shifting device: it moves electricity consumption to cheaper hours, and it stores the resulting heat rather than the electricity itself.

tepeo positions the ZEB as a replacement for the older GEC Nightstor range as well as for gas boilers, and the company has been promoting it to new-build and social housing markets alongside individual retrofits¹⁴. The technology is described by tepeo as UK developed and manufactured¹⁷.

How the ZEB works: ceramic core, off-peak charging, heat on demand

The ZEB uses off-peak electricity to heat a ceramic core, and the stored heat is used on demand later¹⁸. tepeo states that the unit is designed to work with smart, flexible electricity tariffs offering cheaper off-peak electricity, and that charging on a suitable time-of-use tariff can make a significant difference to running costs because more charging can take place during lower-cost periods¹⁹.

The charging decision is automated. tepeo states that the ZEB uses smart charging technology to communicate with the household's energy provider and automatically draws electricity during the tariff's cheapest overnight window, storing it as heat in the thermal core²¹. The smart charging algorithm uses information including heating requirements, the weather forecast and the electricity tariff to plan how and when it charges²². tepeo also states that the unit optimises charging daily and supports grid flexibility²³.

That combination is the core of the running-cost case. A heat battery is not more efficient than any other resistive electric heater at turning electricity into heat; what it changes is when the electricity is bought. The saving, where there is one, comes from the tariff rather than from the conversion. tepeo's own framing is that a suitable time-of-use tariff can make a significant difference to running costs²⁰.

The dependence this creates is worth stating plainly. The ZEB's economics rest on a smart meter and a tariff with a genuinely cheap off-peak window, and on the household being able to shift its heating demand into that window. A household on a single-rate tariff loses most of the advantage. A household that needs heat at times the battery has already discharged falls back on whatever the tariff charges at that moment. tepeo states that the ZEB is recognised as a Works with Octopus smart technology partner and is designed to work with Octopus Energy's smart tariffs²⁴.

What it heats: radiators only, with separate hot water options

The ZEB is a heat-only boiler. tepeo states that it works with a wet central heating system and a hot-water cylinder rather than producing instantaneous hot water, and that a household will need a separate solution for its hot water⁴. For homes upgrading from a combi boiler, which provides both heating and hot water from one unit, the ZEB replaces only the central heating side, and a dedicated hot water solution must be added²⁶.

tepeo does not manufacture hot water systems, but states that the ZEB is compatible with a variety of solutions that can be paired with it, including a traditional cylinder, a smart cylinder or a compact heat-storage solution⁵. The company has also become a distributor for Sunamp's Thermino heat batteries for hot water, which gives households a compact option where cylinder space is tight²⁸.

On the heating side, tepeo states that the ZEB can work with a wide range of existing radiators, thermostats and pipework, including microbore systems, subject to survey². The unit connects directly to an existing wet central heating system, and tepeo describes the upgrade as a seamless way to electrify heating for that reason⁵. One installer case study describes a household choosing the ZEB partly because it worked with their existing pipework²⁹.

The survey is the point at which compatibility is actually confirmed. tepeo's wording is "subject to survey", and the same applies to the wider system: radiator sizes, flow rates and controls all bear on whether the existing installation suits the appliance. A household with a combi and no cylinder space is looking at two changes rather than one, and the hot water decision is best taken at the same time as the heating decision rather than after it.

Storage capacity and specifications: over 40kWh of usable heat

The headline figure is storage. tepeo states that the ZEB holds up to 40kWh of heat, and lists 40kWh of usable storage with a 15 kW heat output². The storage medium is a high-density ceramic core²⁶. The physical size is described by tepeo as roughly that of typical white goods².

The 40kWh figure is the one that determines how long the unit can run without drawing power. A 15 kW output drawing on a 40kWh store gives a finite number of heating hours before the core is depleted, and the exact figure depends on how hard the heating system is working, the outdoor temperature and the fabric of the home. tepeo does not publish a runtime figure in the material reviewed here, so the honest position is that the store is sized to cover a charging cycle rather than a fixed number of hours.

That is the same logic as a home battery, applied to heat rather than electricity. The difference is that heat cannot be exported, sold or used for anything except warming the home and its water. A heat battery's stored energy has one destination. That makes sizing more consequential than it is for an electrical battery: too small a store and the household draws peak-rate electricity on cold evenings, too large a store and the capital cost is spent on capacity that is rarely used.

Cost, the £2,500 grant match and finance options

tepeo states that it is offering a £2,500 early grant match off every ZEB Heat Battery Boiler, so households can upgrade before government heat battery grants become available⁸. The company describes the offer as matching the proposed Boiler Upgrade Scheme grant, and states that it applies until the Boiler Upgrade Scheme opens to heat batteries². tepeo also states that it is working with government to support removal of VAT from heat batteries³.

The effect on the product price is stated by tepeo as reducing the product price to £3,500⁷. That is the product price after the early grant match, not the installed cost. tepeo does not publish an installed price in the material reviewed here, so installation is quoted by a tepeoPRO installer following a survey, and no installed range can be given.

On the scheme itself, tepeo states that the ZEB is not currently supported by the Boiler Upgrade Scheme, and that heat batteries are expected to be included from winter 2026 with a £2,500 grant once standards and scheme rules are in place⁶. Until then, the early grant match is the mechanism by which tepeo reduces the upfront cost. A household weighing the two should note that the timing of the government scheme is described by tepeo as expected rather than confirmed.

Finance is available. tepeo states that the ZEB and its installation can be paid for in manageable monthly instalments³. The company does not publish a rate, term or representative APR in the material reviewed here, so the cost of borrowing is quoted case by case and should be read from the finance agreement rather than assumed.

For energy independence, the cost picture is mixed. The ZEB removes gas standing charges and gas price exposure, and the grant match reduces the capital barrier. It does not remove the standing charge on electricity, and it does not remove the need for a tariff with a cheap overnight window to make the running costs work. The capital cost is also front-loaded in a way that gas boiler replacement is not, which is why the finance option and the grant match matter as much as the headline price.

tepeo the company: B Corp status, UK manufacturing and support

tepeo is a certified B Corporation, and states that it is recognised as an Ethical Consumer Best Buy¹². The company describes the ZEB as UK developed and manufactured, and one customer account refers to manufacturing in Britain alongside a personal, supportive experience¹⁷. tepeo states that it provides dedicated UK technical support³.

Support runs through a network of tepeoPRO installers as well as directly. tepeo publishes a customer service email address, customer.service@tepeo.com, and states that the ZEB should have an annual Health Check covering water quality, filters, wear and tear, leaks, electrical safety and system performance, including any parts needed, with a yearly reminder provided³. One customer account describes maintenance as once a year, just like an old gas or oil boiler, and notes the unit can be turned off entirely in summer¹¹.

The ZEB comes with up to a 10-year guarantee¹⁰. As with any long manufacturer warranty, the terms that matter are the ones in the document: what is covered, what voids it, and whether servicing must be carried out by an approved engineer. The annual Health Check is the obvious condition to check, since a missed service is a common reason a claim is refused. Households comparing cover across brands can read more on manufacturer warranties and on registering a warranty and keeping it valid.

The company's status is a genuine part of the buying decision for a product with a ten-year guarantee. tepeo is trading, holds B Corp certification and has distribution agreements in place, which is the position a household should verify at the point of purchase rather than assume from a page written earlier. Buyers of any emerging heating technology are exposed to the manufacturer's continued existence for the life of the warranty, and that exposure is worth weighing alongside the specification. The wider context for electric heating brands is covered in electric radiator and storage heater manufacturers, and the ownership picture behind UK energy brands in who owns which energy brand.