How to Reset a Boiler – Step by Step Guide

Boilers have an in-built safety mechanism to ‘lockout’ should there be a fault within the system for the safety of both the property and for the protection of the parts inside the boiler.

This article will pinpoint common issues that cause a boiler to lockout and the best approach to get the boiler back up and running again.

Watch: How to Reset a Boiler:

When to Reset a Boiler

Boilers will lockout when they sense a problem, however, this can occur for an array of reasons. Common factors are either a fault within the system or an unsafe operating condition such as a gas supply issue.

Modern boilers can provide an error code which will be displayed within the boiler window, aiding diagnosis behind the reason of why a boiler was shut down.

The error codes and the relevant description of the matter can usually be found either within the manufacturer’s manual or on their website.

Other common reasons that a boiler may need resetting could be a power failure or gas supply issue. Always check the property’s fuse box hasn’t tripped before attempting to reset the boiler.

If you need to reset your boiler too often, it may be a sign of a more significant fault, such as a faulty PCB, a boiler leak or a central heating pump problem, and if your boiler isn’t igniting, it may be time to consider getting a new boiler quote.

How to Reset a Boiler

The process to reset a boiler will vary depending on the make and model of the boiler unit itself. Therefore it is always best practice to refer to the manufacturer’s manual when needed to reset the boiler.

The majority of boilers have a rest button.

This is the typical procedure for resetting a boiler:

  • Push the reset button
  • Wait for the boiler to re-ignite

Once the boiler reset process has taken place, leave the boiler for a few minutes to reignite and re-pressurise.

Why Has the Boiler Locked out?

As already mentioned, there are a number of reasons why a boiler can lockout. Some of the most common reasons are as follows:

Water Pressure Issues

Should the water pressure be too low or too high, the boiler will lockout, however, continual usage of the heating system during water pressure issues can cause damage to the boiler’s internal parts.

An operating boiler will typically have a pressure reading of between 1 and 2 bars of pressure.

If your boiler is showing a pressure below 1, you can attempt to add pressure to the system by the use of the taps, which are usually located underneath the boiler.

Always check the boiler’s manufacturer boiler manual to locate the taps and to clarify the process before making any pressure adjustments.

However, if the pressure reading is above 2, other issues or faults could be at play and therefore it is time to seek assistance from a specialist engineer to review the system and advise the next steps.

Failure to Ignite

Most boilers will attempt to ignite three times before locking out. There can be many causes of an ignition failure; from a blocked gas valve or burner to a faulty fan or electrode and ignition lead.

All of these issues mentioned above will require the assistance from a Gas Safe registered engineer to confirm a diagnosis and resolve the matter safely.

A Blocked Heat Exchanger

A heat exchanger is a part within a boiler unit which can become blocked due to debris or limescale within the system.

In some cases, the heat exchanger can be cleared of the blockage, however more frequently the limescale build-up can cause damage to the part itself resulting in the part needing to be replaced.

A qualified heating engineer will be best placed to check out the heat exchanger and provide the best cause of action.

In addition, regular boiler servicing can monitor the build-up of limescale and debris within a boiler system. Also, an engineer can make the recommendation at an appropriate time to undertake a system flush to remove the build-up.

Issues with the fan or flue

The fan and flue work in conjunction to keep the boiler and the property safe from harmful gasses. The fan inside the boiler should create a draught to push the gases produced by the boiler into the flue and then out of the property via the flue.

However, when a boiler detects that the fan is not working properly, the safety mechanism will shut down the boiler limiting the danger of possible additional gasses.

Should it be suspected that the fan is faulty, or the flue is blocked, a specialised engineer will be required to confirm the diagnosis and resolve the matter.

Due to the expense of replacing a fan, always consider the age of the boiler and whether it would be deemed more cost-effective to invest in a new boiler.

Is your boiler losing power? Or is your boiler pressure too high? If your boiler is old, past its warranty, it may be time for a new boiler replacement.

The Boiler won’t turn back on after Resetting

Should the boiler not turn on after resetting or require regular resetting, it could be a sign of a faulty part. Common part faults could include pump faults, leaks within the system or intermittent issues with electrical parts.

An engineer would need to be called to provide a thorough diagnosis of the underlying matter and make suitable recommendations.

In this scenario, it is always worth considering the age of the boiler in situ before embarking on a long list of repairs.

A replacement boiler, although a large expense, can be more economical over the longer period, providing a more reliable service and energy efficiencies.

How to Reset a Boiler Summary

There are a number of reasons that can result in a boiler not firing up. It may be prudent to attempt some simple troubleshooting steps and perhaps two resets in-house to see if the matter can be resolved.

However, if the lockouts continue or there is any doubt regarding the cause of the matter, it would be best to seek the assistance of a qualified heating engineer.

Also, remember that ageing boilers will begin to breakdown more frequently and will therefore soon rack up call out charges and repair costs.

Pressure issues are also an inevitable factor of an ageing boiler due to limescale build-up and wear and tear on the internal parts, and therefore consideration should be taken to the timing of a boiler replacement.

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