If you’ve noticed that your boiler keeps turning on and off or fires up for no reason, there could be something wrong with it. Here’s why your boiler keeps turning off, what to do about it, and how to keep it working properly in the future.

How often should my boiler turn on and off?

Boiler manufacturers recommend that the boiler run for 3-4 hours and then turn off for an hour. This is to allow the system to cool down before turning on again, which will extend its lifespan. The average British home uses around 8kW of power per hour. So if you have a 7kW boiler and it’s running for three hours, that amounts to 21kWh of energy used per day.

Why does my boiler fire up and then cut out?

Experiencing a boiler that fires up only to quickly cut out can be a frustrating issue. If you’re facing this problem, it’s essential to understand that several factors could be contributing to this behavior.

  • Thermostat Issues: A malfunctioning thermostat is often at the heart of erratic boiler behavior. If your thermostat is sending incorrect temperature signals to your boiler, it might cause the unit to cycle on and off abruptly.
  • Water Pressure Problems: Boilers rely on adequate water pressure to function correctly. If your boiler’s water pressure is too low, it might struggle to maintain a steady operation, causing it to fire up and then shut down.
  • Airlocks and Blockages: Airlocks or blockages within the heating system can disrupt the flow of water, leading to irregular heating cycles.
  • Faulty Sensors: Modern boilers are equipped with safety sensors that monitor various parameters. If any of these sensors are malfunctioning or sending incorrect signals. Your boiler might shut down as a protective measure.
  • Lack of Fuel or Gas Supply Issues: For gas-powered boilers, a lack of fuel supply or gas-related issues can cause the unit to fire up and then shut down.
  • Limescale Buildup: Limescale accumulation on the heat exchanger can insulate it and cause overheating, triggering the boiler to cut out.
  • Electrical Problems: Faulty wiring, corroded connections, or electrical component issues can lead to erratic boiler behavior.

What to do if the boiler keeps cutting out?

If your boiler keeps cutting out, there are a few things that you can check.

  • Check the level of water in the tank. If it is too low, refill it and then turn it on again.
  • Check the pressure gauge on top of your boiler. If it shows too high or low pressure, adjust accordingly and then restart your heating system again after making sure everything else is working correctly (see below).
  • Check if there’s anything blocking airflow to or from inside your system–this could lead to overheating problems as well as shutting down unexpectedly when trying to operate at full capacity during extreme temperatures outside or when using certain other types of equipment inside such as stoves or ovens which produce large amounts of heat themselves!

Why does my boiler keep turning on and off?

Dealing with a boiler that constantly turns on and off can be frustrating. Here are some possible reasons why your boiler keeps turning on and off.

Thermostat Malfunction

A malfunctioning thermostat can lead to erratic boiler behavior. If your thermostat is sending incorrect temperature signals to the boiler, it might cause it to cycle on and off frequently. This issue could stem from a wiring problem, aging components, or even dust accumulation affecting its accuracy.

Short Cycling Due to Overheating

Boilers are equipped with safety mechanisms to prevent overheating. If any of these safety features, such as the high-limit switch or the pressure relief valve, are faulty or misconfigured. They might trigger the boiler to shut off prematurely as safety assurance, causing short cycling.

Airlock or Circulation Problems

Airlocks in the system’s pipes or an insufficient water flow due to circulation problems can lead to the boiler shutting off to prevent damage. Airlocks can hinder the movement of water, causing the boiler to overheat quickly and cycle off.

Blocked or Dirty Components

Dirt, debris, or mineral deposits can accumulate in various components of your boiler, including the burners and heat exchangers. This buildup restricts proper heat transfer and can cause the boiler to shut down frequently.

Incorrect Boiler Sizing

If your boiler is oversized for your home’s heating needs, it might heat up the space rapidly and shut off, only to restart shortly after. This can create a cycle of frequent on-off behavior, affecting energy efficiency and the longevity of the system.

Electrical Problems

Electrical issues, such as faulty wiring, loose connections, or a malfunctioning control board, can lead to intermittent cycling. Electrical glitches can disrupt the communication between various boiler components. Causing the unit to shut down unexpectedly edgy.

Water Pressure Fluctuations

Low water pressure or fluctuations in the water supply can trigger the boiler’s safety mechanisms, causing it to turn off.

How do I keep my boiler running?

  1. Make sure the flue is clear. If it’s blocked, your boiler will turn off.
  2. Set your temperature correctly. Boilers need to be set at a certain temperature in order to run properly and efficiently.
  3. Check that there’s enough water in your tank for heating purposes. If there isn’t enough, the boiler shuts down temporarily until more water has been added. You should also check whether any pipes leading from the tank are leaking!
  4. The last thing to check is that the pressure valve is working correctly. If this part isn’t functioning properly. It will cause too much pressure in your system and lead to overheating.


In short, a boiler that keeps turning off is a serious problem. It can lead to more serious issues if left unattended, like frozen pipes and potential flooding. If you notice your boiler is turning off at random times or not working at all, contact a professional immediately!

About the author

About the author

Yunchong Shang

Yunchong is a seasoned boiler expert with over five years of hands-on experience in the boiler industry. He has expertise in various types of boilers, including fire-tube, water-tube, and steam boilers, while also staying up-to-date with the latest technological boiler.

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