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My ZEB is charged but my heating isn’t coming on, is this normal?

This article helps you understand when your ZEB is working normally and when there might be an issue.

This article explains:

  • Quick checks to confirm the ZEB is actually delivering heat.
  • Things you can try yourself.
  • When to contact tepeo Support or your installer.

1. Quick checks: is the ZEB actually delivering heat?

Before assuming there’s a problem, check that the ZEB is being asked to deliver heat and is actually delivering heat.

Check the tepeo app and ZEB comms box

In your tepeo app:

  • Is there an active call for heat?
  • Does the app show that the ZEB is discharging rather than idle?

On the ZEB comms box:

  • Is the discharge indicator showing that the unit is providing heat?
  • Is the fault indicator flashing indicating there is a fault preventing operation?

If there is no call for heat when you expect one, move on to checking your thermostat and heating schedule.

Check your thermostat and heating schedule

  • If you have a wireless thermostat, check the batteries, there may be an indicator to say they’re flat or the screen may be blank. Refer to the instructions supplied with your controls for guidance on replacing them if necessary.
  • Confirm your target temperature is what you really want (for example 20–21°C, not lower) and that the temperature you’re requesting is higher than the actual temperature in the room where the thermostat is located.
  • Review your heating schedule:
    • Are you heating for the times you actually need heat (e.g. mornings and evenings)?
    • Are there eco/away/holiday modes or other features limiting when heating can run?

If your thermostat is not calling for heat at the right times, adjust the schedule or mode and monitor performance for a day or two. All thermostats are different, refer to the instructions supplied with your controls as to how to set them correctly.

Check your radiators

When you know there is an active call for heat (from the app/controls):

  • Do the radiators feel consistently hot across most of their surface, or only warm at the top/bottom? Radiators can take some time to warm completely, if your room thermostat reaches the desired temperature and the demand stops, the radiator may not get completely hot.
  • Are some radiators turned down or off using TRVs (thermostatic radiator valves)?
    • Rooms with radiators turned down or off will naturally be cooler.

If the ZEB is not discharging when you expect it to, or radiators stay cold despite a clear call for heat, you may need a separate troubleshooting guide such as “No heat from ZEB / not responding to call for heat”.

2. Understanding what “normal” can look like

A ZEB stores a fixed amount of energy each time it charges. How long that charge lasts depends on:

  • Outside temperature – colder weather means more heat loss.
  • Property heat loss – insulation levels, windows, draughts, and overall size of your home.
  • Radiator system – number, size and balance of radiators.
  • Setpoint and usage – the temperatures and hours you’re trying to maintain.

Example patterns

  • On a mild day, one full charge may comfortably cover both a morning and evening heating period.
  • On a cold day, the same charge may:
    • Only comfortably cover a longer morning or evening session, or
    • Require a Boost to maintain comfort later in the day.

What is usually normal

It’s usually normal for:

  • The charge percentage to drop faster when:
    • It’s very cold outside, or
    • You are heating the whole home to a high temperature for many hours.
  • You may need to adjust schedules or Boost more often in colder weather.

This doesn’t always mean there’s a fault with the ZEB.

3. Things you can try yourself

If your ZEB appears to be working, but the home still doesn’t feel as warm as you’d like, try the following.

Adjust your heating schedule

  • Concentrate heating into the times you most need it.
    • For example, 06:30–08:30 and 16:30–21:00.
  • Avoid trying to maintain high temperatures all day on a single charge, especially in very cold weather.
  • Trial a lower but more consistent target temperature, keeping temperature variations within the home to within a few degrees, creating a more stable environment 

If you’re using a custom charging schedule, you may also want to review how your charge timing lines up with your heating periods and tariff.

Review your target temperature

  • If you usually set 21°C, try 20°C and see if comfort is still acceptable.
  • Every degree higher requires more energy. A slightly lower setpoint can help your charge last longer.

Reduce the load on the system (if possible)

  • Turn down radiators in rooms you rarely use.

This focuses the available energy on your main living areas, which can improve comfort where it matters most.

Look for obvious system issues

  • Radiators that are warm at the bottom but cold at the top may have air trapped and need bleeding.
  • Radiators that stay cold when others are hot may have:
    • Closed valves or TRVs, or
    • A stuck valve.

Only bleed radiators or adjust valves if you feel confident and it is safe to do so. Never bleed radiators when the system is hot or there is a demand for heat. If in doubt, contact your installer or heating engineer.

4. When it might not be normal

Even with the above in mind, some patterns can point to an underlying problem:

  • The ZEB consistently runs out of charge very quickly even on milder days.
  • Parts of the home remain cold even though radiators are hot and the system is heating normally..
  • You have:
    • Reasonable heating schedules (focused on the times you need heat),
    • Reasonable target temperatures (e.g. around 18–21°C)
    • Some radiators turned down in unused rooms,
      but you still need to Boost frequently to reach basic comfort.

Possible causes include:

  • System design issues (e.g. undersized or decorative radiators, very high heat loss, system balancing problems).
  • Controls issues (e.g. thermostat placement or configuration).
  • A fault with the ZEB or with the wider heating system.

In these scenarios, it’s best to get support.

5. When to contact tepeo Support or your installer

You should contact tepeo Support or your installer if:

  • You cannot maintain a comfortable temperature even after:
    • Adjusting heating schedules,
    • Setting realistic target temperatures
    • Reducing heating in low‑use rooms.
  • Radiators don’t get properly hot, or some don’t heat at all.
  • You notice unusual behaviour, such as:
    • Odd noises from the ZEB or system,
    • Rapid cycling on/off,
    • Very rapid charge depletion that doesn’t match outside conditions.

Information to include when you contact us

Sharing the details below helps us quickly understand whether what you’re seeing is expected for your home, or whether further investigation is needed:

  • A description of:
    • Your current heating schedule (times and setpoints).
    • Typical indoor temperatures and how quickly they change.
    • Any relevant screenshots of the app or thermostat/clock
  • Any recent changes:
    • To your home (e.g. new insulation, windows, draught‑proofing).
    • To your controls or tariff (e.g. new thermostat, new time‑of‑use tariff).

Safety notes

  • Never bleed radiators or work on valves when the system is hot or there is a demand for heat.
  • Do not open the ZEB casing or attempt any internal repairs yourself.
  • If you notice burning smells, smoke, or persistent unusual noises, turn the system off if it is safe to do so and contact tepeo Support or your installer immediately.