We’ve compiled a list of our most frequently asked questions. If you can’t find the answer to your query please send us an email at customer.service@tepeo.com and we’ll get back to you.


What is the storage medium made of?

  • Proprietary mix of high-density, inert, non-toxic and low impact materials

How much energy does it store?

  • 40kWh of usable thermal energy

How much power can it output?

  • 15kW maximum

What temperature water can it supply?

  • Just like a fossil fuel boiler the ZEB can supply any water temperature up to 80°C in a suitably sized home as set out here. Your current boiler won’t be higher than this so you won’t notice a difference.

How efficient is the Zero Emission Boiler?

  • Installation within the heated envelope of the home rates a ZEB at 100% efficient at converting fuel into heat, as the ZEB converts 100% of its electricity consumption into heat (classified as 100% efficient for EPC purposes); installation in garages or unheated spaces is not optimal and may result in increased standing losses and reduced capacity.

  • We are working on improving this performance, such as advising our customers to use immersion heaters with a timer for hot water heating, rather than using the ZEB for water heating, particularly in the summer months.

  • It’s worth noting that when the ZEB is charging, it becomes a little bit warm itself – the surface temperature is cooler than a radiator but there are heat losses, which will heat the area where the ZEB is located.

How long does it take to charge?

  • 4-5 hours from empty. It can deliver heating after half an hour (from cold).

What are the dimensions of the ZEB?

  • 98cm (height) x 60cm (width) x 66cm (depth) – but it needs clearance of 7cm above and 5cm on all sides.

How heavy is it?

  • 375kg.

How does it work?

  • The Zero Emission Boiler (ZEB®) is an innovative low carbon alternative to a fossil fuel boiler. Using a Smart Charging algorithm, the ZEB ‘charges up’ with off-peak electricity and stores this as heat inside its core, producing heating and hot water on demand to keep costs low.

How long will it last?

  • We’ve designed the core of the ZEB so it doesn’t degrade over time, in fact there’s a good chance it will outlast the home it’s installed in! However, the ZEB still needs to be maintained, like all boilers, and so we provide two options to support this – a standalone annual ZEB Health Check or our tepeo Care Plan here.

How often should the ZEB need servicing?

  • The ZEB should have an Health Check (typically costing £149), which involves a tepeo trusted engineer checking the water quality in your heating system, clearing filters, visually inspecting parts for wear and tear, including cleaning where necessary, checking for leaks, carrying out an electrical safety test and generally ensuring the ZEB is running smoothly.

  • Unlike an annual service for a traditional heating system, a ZEB Health Check from tepeo includes all of the parts that may be needed – without any hidden costs.

  • For comparison an annual heat pump service typically costs around £200-£250 and a standard boiler service costs up to £120-£130.

  • You’ll automatically receive a yearly reminder of when your Health Check is due once your ZEB is installed.

Where does tepeo deliver to?

  • To see if we cover your area for delivery, please click here.

Do I need to register my ZEB?

  • Your ZEB will be automatically registered during installation so there’s no need for you to do anything. The 10-year guarantee will be activated from installation.

    Terms and conditions apply.


How do I report security concerns about the ZEB or tepeo App?

  • Please contact the customer service team if you have concerns about security of the ZEB or tepeo App (see the Contact Us page for details).

How long will tepeo provide security updates for the ZEB (under the PSTI regulations)?

  • We will provide security updates for a minimum of 5 years from date of purchase.

How much does the Zero Emission Boiler cost?

  • A ZEB costs £6,000 to purchase, which includes VAT and delivery. Currently, the ZEB isn’t zero-rated for VAT purposes (20% VAT applies) and doesn’t receive any subsidies (but we’re working on it).

  • Installation costs vary and depends on your home, heating system requirements and local installer rates – we can put you in touch with a tepeoPRO installer in your area to get a quote specific to your home.

  • We can also provide a tepeo Care Plan subscription to help maintain your 10-year guarantee. Find out more here.

What tariff do you recommend?

  • Any time of use tariff can be used. Octopus, OVO, EDF, Scottish Power and others offer these, often marketed for EV drivers. Which one will be the cheapest for you will depend on your other consumption needs.

  • You should also explore what are the best boiler settings for you to save money.

Does it work with Octopus Agile?

  • Octopus Agile is a fully dynamic tariff which has a different price for every half hour of the day. The ZEB can automatically optimise charging for this tariff.

Does it qualify for the Boiler Upgrade Scheme or other grant funding?

  • As this is a new technology, it does not yet qualify for any grant or subsidy support. We hope to be able to change this in future and to get tepeo’s ZEB on some of the numerous government incentives to reduce carbon emissions.

Will my heating costs go up?

  • This depends on your tariff & heating demand. You can check out our new boiler savings calculator which will help you figure out your potential energy savings and carbon savings.

Where should I put my Zero Emission Boiler?

Can it go in my loft?

Electrical and Plumbing Installation

Can my plumber/electrician install it?

  • All installations must be installed and commissioned by tepeo or a competent and qualified installer who is registered with tepeo. All installations must also be in accordance with the manufacturer’s instructions, applicable legal requirements, regulations and industry standards. They can find out how to become registered here.


What electrical connections are required?

  • Power via isolator, directly from the consumer unit (50A breaker/RCD, 10mm2 min cable size).
  • Power/Databus from ZEB to Comms Box (and on to third party heating controls).
  • Heating system power output 3A fused spur (non switched) to wiring centre/10 way junction box.
  • Thermostat heat demand (230v or Volt Free).
  • External pump (controlled directly by ZEB pump overrun).

What plumbing connections are required?

  • Central Heating – Flow/Return 22mm copper – solder or compression/press fit.

Anything else required?

  • Isolation valves – on both flow and return so the ZEB can quickly be isolated from the heating system for maintenance without draining the system.
  • Automatic bypass valve – to ensure minimum flow through ZEB even when the heating system valves have closed.
  • Pressure relief valve – to ensure the system pressure stays within limits.
  • Magnetic System Filter – to help ensure the ZEB heat exchanger stays free from contamination (which would reduce performance).

Anything else to bear in mind?

  • You can simply retain the existing thermostat and timer. There’s no need to adjust any settings, just use the ZEB as if you were using your fossil fuel boiler.
  • In fact a ZEB works with any thermostat and heating type including radiators, underfloor heating, microbore systems, mixed circuits and combinations thereof. It can be set to supply 35-80ºC flow temperature – as required by the system.
Power Supply, Smart Charging & Algorithms

Do I need a smart meter?

  • No – the ZEB will still be able to optimise charging so it minimises your carbon footprint. However, to access lower-cost electricity tariffs too, you will need a smart meter and a smart tariff from your energy supplier.

Can ZEB draw electricity at the same time as my EV charger?

  • Yes, a typical charger will draw 30A, the ZEB 40A, so together 70A – less than the typical 100A household limit.

My heating demand is high – could I get two units and charge both overnight?

  • This is theoretically possible, as each ZEB draws 40A so in combination they would draw 80A vs. a household limit of 100A.
  • We hope to support parallel running soon, but cannot install ZEBs in this setup today.


What happens in a power cut?

  • Just as with a conventional boiler, the circulation pump will not work if there is no power supply, so heat will not be provided. The stored heat will remain in the core for several days but will slowly be lost.


What happens if I demand heat at a faster rate than it can be replaced in the ZEB?

  • The ZEB discharges in the range 0-15kW but charges at 9kW – the ZEB charge will deplete faster than it can be replaced if the discharge rate exceeds this.


I have solar PV, can I use the excess to charge the ZEB?

  • This feature is currently under development.


How does Smart Charging Work?

  • Our Smart Charging algorithm charges the ZEB at the cheapest and greenest times of the day, ready for when you need it.
  • This factors in:
  • Local weather.
  • How much heat your home uses.
  • The carbon intensity of electricity and the pricing of your energy tariff.
  • Like many smart electric boilers, the ZEB works best with “time of use” or “flexible” tariffs where the price you pay for electricity changes throughout the day.
Carbon savings

Ready to find out more?

A tepeo ZEB in a two-bed home

I’m a homeowner

The next step is to find out if a ZEB is the right low carbon heating solution for you. Just sign-up using the form below, we’ll check some details and let you know if the ZEB is a good fit for your home.

I’m an installer

We’re building a network of motivated, experienced heating and electrical engineers to help us install our Zero Emission Boilers across the UK.