Why Is My Heating Not Coming On? Common Causes & How to Fix Them

When the temperature drops, the last thing you need is your heating refusing to turn on. Whether you have an oil boiler or a gas boiler, there are a number of simple checks you can make before calling an engineer. In this guide, we’ll walk you through the most common reasons your heating might not be working – and when it’s time to call in the professionals.

At Total Energy Services, our fully qualified, insured and DBS-checked engineers work across Dorset, Wiltshire, Hampshire and Somerset, helping households stay warm all year round.

1. Check Your Thermostat Settings

It might sound obvious, but thermostat issues are one of the most common causes of heating problems.

✔️ Things to check:

• Is the thermostat set to heating instead of cooling or off?

• Is the temperature set higher than the current room temperature?

• If it’s a wireless thermostat, are the batteries still working?

• Is the thermostat communicating properly with the boiler?

If the thermostat has lost connection, your heating won’t turn on at all.

2. Your Boiler Pressure Is Too Low

Most boilers need pressure between 1 and 1.5 bar.
Low pressure can prevent your heating from firing.

✔️ Signs of low pressure:

• A flashing error light

• A pressure gauge below 1 bar

• No hot water as well as no heating

You may be able to top this up yourself, but if it keeps dropping, you should get it checked by a qualified engineer.

3. A Tripped Fuse or Power Issue

If your boiler has no electricity, it won’t work.

✔️ Check:

• Your fuse box (has a circuit tripped?)

• Boiler display (is it blank?)

• Spur switch near the boiler (is it turned ON?)

• Timers/clocks after a power cut

A quick power reset can often fix the issue.

4. Problems With the Programmer or Timer

Older timers can drift or malfunction, especially after a power cut.

✔️ Check:

• Has the clock reset?

• Are the heating “on” times correct?

• Is it set to once, twice, or on all day?

If your timer is particularly old, upgrading to a smart controller could save money and prevent future issues.

5. Frozen Condensate Pipe (Very Common in Winter)

Condensate pipes often run outside and can freeze, causing your boiler to lock out.

✔️ Signs of a frozen pipe:

• Gurgling sounds from the boiler

• Fault codes related to drainage

• Heating shutting down on cold mornings

Gently pouring warm (not boiling) water over the pipe can defrost it, but prevention — such as insulation — is key.

6. Airlocks in Radiators or Pipework

If some radiators heat up while others stay cold, you may have an airlock.

✔️ Solution:

Bleed your radiators to release trapped air.
If the entire system isn’t heating, the airlock may be in the pipework and will require a heating engineer.

7. Oil Boiler Specific Issues

For homes with oil heating:

✔️ Check:

• Do you have enough oil in the tank? (It’s more common to run out than you think!)

• Is the oil line filter blocked?

• Has the boiler locked out and needs a reset?

If you’ve recently had an oil delivery, sludge disturbance can sometimes block filters.

8. Gas Boiler Specific Issues

Gas boilers may fail to ignite due to:

• Faulty ignition

• Blocked flue

• Fan issues

• Frozen pipes

• Safety lockouts

These issues require a Gas Safe registered engineer to diagnose safely.

9. A Faulty Pump

If your boiler fires but no heat reaches the radiators, the problem may be the circulation pump.

Signs include:

• Boiler overheating and shutting down

• Radiators staying cold

• Strange humming or grinding noises

10. Time to Call an Engineer

If you’ve checked everything above and your heating still won’t come on, it’s time for a professional diagnosis.

At Total Energy Services, we fix and service all types of boilers including:

• Oil boilers (Grant & Worcester Bosch accredited installers)

• Gas boilers (Vaillant & Glow-worm accredited installers)

• Combi, regular and system boilers

We work in homes, schools, hotels, medical centres, holiday parks, pubs, restaurants, and more.

Need Help Getting Your Heating Working?

Our friendly local engineers can diagnose and repair heating issues quickly.

📞 Call us: 01258 472132
🌐 Book online: totalenergy.co.uk
🏡 Covering Dorset, Wiltshire, Hampshire & Somerset

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