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How to Reset a Boiler


One morning, you may wake up and realise that your boiler that worked flawlessly the other day won’t fire up. This means that you will end up with no hot water and central heating. However, you should not panic as this is a common issue, and a simple reset might get your boiler up and running again.

The reason why you have no heating from your boiler is most likely due to the boiler going into a lockout. A lockout is a safety shut down procedure that the boiler initiates when there is an internal fault in the system that might damage the boiler or create unsafe conditions where the boiler continues operating.

What to do if you suspect your boiler is in lockout

Of course, the first thing that comes to your mind when you suspect your boiler has gone into lockout is to move quickly and press the reset button. However, this is wrong as the first thing you should do is ascertain the cause of the boiler lockout and resolve it before attempting to reset the boiler.

This is usually easy as most modern boilers display an error or fault code when it goes into a lockout. Other boilers will flash red or green lights besides showing the fault codes. To find out the cause of the lockout, reference the displayed fault code with your manual or search it online. And once you have determined the issue with the boiler, you can proceed to resolve the issue, but if you are unsure about it, contact a heating engineer before attempting to reset the boiler.

Reasons why your boiler has gone into a lockout

Boiler lockouts are reasonably common, with one in five boilers going into lockout each year. Here are some of the common reasons behind boiler lockouts and how to resolve them.

  1. Lack of power to electronic components

Regardless of its fuel type, your boiler cannot operate without electricity to the main electronic components, such as the PCB unit. Therefore, the first thing to check before attempting to reset your boiler is whether or not there is power in your property, and in extension, your boiler.

If there is power in your home, you need to inspect the power supply to the boiler and check whether there are blown fuses or tripped electrics on the line. Once you resolve these and restore power to your boiler, you can reset it.

  1. Low or high water pressure

Combination or “combi” boilers which account for around 80% of all the boilers installed in UK households, cannot function if the water pressure in the system is too high or too low. As such, if your boiler has locked out, you should check to ensure the system pressure is around the recommended 1.5 bar.

If the pressure is low, say, below 1 bar, you need to repressurize the boiler by adding water to the system through the filling loop. On the other hand, if the boiler pressure is higher than 2.5 bars, you need to lower it by bleeding your radiators.

  1. Sludge buildup

Limescale buildup will lower the efficiency of your boiler by up to 12% by interfering with essential components such as the heat exchanger. Accumulation of limescale and sludge in your boiler’s heat exchanger might damage parts of the boiler, and to stop this from happening, the boiler will initiate a lockout. Consider clearing out your boiler system by conducting a power flush to resolve this issue.

  1. Ignition failure

If your boiler fails to ignite three times in a row, it will initiate a lockout and will not fire up until the underlying issue is resolved. Some of the common reasons behind boiler ignition failure are:

  • A faulty gas valve
  • Low fuel supply
  • Low gas pressure
  • Faulty ignition lead

How to reset a boiler

Now that you have ascertained and fixed the issue behind your boiler locking out, it is time to reset your boiler by pressing the reset button, usually located at the front or back of the boiler unit. If you can’t find this button, you should refer to your boiler manual, which will specify where it is located. The boiler manual will also outline the reset procedure for your particular boiler model.

Once you have located the reset button, you should press and hold it for somewhere between one and five seconds. If the rest is successful, the flame will ignite, and the fault code on the display panel will disappear. Additionally, the boiler will stop flashing the red or orange lights and flash a green light instead.

If the boiler reset isn’t successful, the boiler won’t ignite, and you should contact a qualified heating engineer who will locate the fault and fix it for you. Just ensure you don’t keep pressing the reset button repeatedly as it might get stuck and create additional problems.

How to reset a Worcester boiler

Worcester boilers are available in a wide range of models, each having a unique reset procedure. Here are the reset procedures for some of the leading Worcester boiler models.

CDi Classic: Press the reset button for three seconds

CDi Compact: Press and release the reset button after a few seconds

Greenstar i: Quickly press and release the reset button

Greenstar 2000: Hold the up and down buttons simultaneously until the error symbols disappear or “reset” appears on the display

Greenstar i Junior: Press and hold the reset button for 5 seconds

How to reset an Ideal boiler

The method of resetting an Ideal boiler varies depending on the boiler model you have. For an Ideal Logic boiler, you need to turn the control knob to the reset position and back to your desired setting. For an Ideal Logic+ boiler, you simply have to push the restart button, while for the Vogue series, a simple push on the small “r” button will suffice.

How to reset a Vaillant boiler

To reset a Vaillant boiler, you need to locate the rest button, which usually has a flame with a cross on it. If your boiler is an ecoTEC Plus series, you need to press and hold this button for one second. On the other hand, if it is an ecoFIT Pure, you need to press and hold the reset button for around 5 seconds before releasing it.

How to reset a Baxi boiler

Baxi boilers have three reset methods depending on the model of boiler you have on your property. If your model has a reset button, you need to press and hold this button until the red light that flashes or remains constantly lit during a lockout turns off. If the reset is successful, the burner light will switch on to show you that the boiler is up and running again.

Alternatively, if your boiler has an on/off/selector switch, you first need to open the fascia display and check whether there is an error code or a flame failure light. Next, turn the selector switch to the R (reset) position and hold it for five seconds before releasing it. If the operation is successful, the error code should disappear, or the flame failure light would go off.

For Baxi boilers that use a thermostat control knob for resting, you need to turn the temperature control knob in an anti-clockwise direction and hold it down until the red light goes out. Once done, return the thermostat knob to your normal setting, and the boiler will fire up again.

How to reset a Glow-worm boiler

To reset or reboot a Glow-worm boiler, press the reset button and hold it down for five seconds. This should be enough to clear the error code, and your boiler will spring back to life. If, however, this doesn’t work, you will need to call a certified heating engineer.

How to reset a Vokera boiler

Resetting a Vokera boiler is relatively easy as you simply have to move the mode selector switch to the OFF/RESET position. Next, push the button back to the desired position, which can either be “hot water only” or “heating and hot water”. If the procedure is successful, the flashing red light will disappear and be replaced by a green light.

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