How to reset your boiler: A step-by-step guide

Boilers are essential to any home's heating system, providing hot water and keeping your living space warm. 

However, sometimes boilers encounter issues that cause them to lock out or stop working properly. Resetting your boiler can often resolve these issues and get your heating system back up and running.

In this handy guide from the experts at JustFix, we'll explain how to reset a boiler, provide top tips for maintaining it, and tell you when to call a heating and gas engineer.

What is a boiler lockout?

A boiler lockout occurs when a boiler detects a problem and automatically shuts down as a safety feature.

This can happen for various reasons, including low pressure, a faulty pump, a blocked heat exchanger, or ignition failure. When a lockout occurs, your boiler typically displays an error code or a flashing light to indicate the issue.

It's important to refer to your boiler's manual to understand the specific fault code and follow the reset instructions carefully.

If you're still unsure after checking the manual, contact a local heating and gas engineer.

Top tips for maintaining your boiler

• Regularly check boiler pressure: Maintain the pressure within the recommended range to ensure efficient operation.
• Bleed radiators: Trapped air in radiators can affect your boiler’s performance. Bleed your radiators regularly to keep your heating system running smoothly.
• Annual servicing: Have your boiler serviced annually by a gas-safe registered engineer to ensure it is in good working condition and to catch any potential issues early.
• Monitor for leaks: Regularly check for any signs of leaks around your boiler and heating system. Leaks can lead to pressure drops and other problems.
• Keep the boiler clean: Ensure the area around your boiler is clean and free from dust and debris, which can affect its performance.

Step-by-step guide to resetting your boiler

Essential tools and materials

Before you begin the reset process, make sure you have the following:

• Boiler manual (for specific reset instructions)
• Flathead screwdriver (if needed for accessing the reset button)
• Protective gloves (optional)

Without further ado, let’s reset your boiler.

1. Identify the issue

First, determine why your boiler has gone into lockout mode. Look at the display screen or control panel for any error codes or flashing lights. Refer to your boiler manual to understand what the fault code means. 

Common issues include low water pressure, ignition failure, or a blocked plate heat exchanger. A gas-safe registered engineer can help you to identify these. 

2. Check the boiler pressure

Boiler pressure is crucial for the proper functioning of your heating system. Most modern boilers require a pressure range of 1.0 to 1.5 bar. Locate the pressure gauge on your boiler and check if the pressure is within the normal range. 

If the pressure is too low, you may need to top it up by adding water to the system. Follow the instructions in your boiler manual on how to do this safely.

3. Check the gas supply

Ensure that the gas supply to your boiler is on. Check that the gas valve is open and that there are no issues with the gas supply in your home. 

If you think there might be a problem with the gas supply, contact a Gas Safe registered JustFix engineer and report the issue to the National Gas Emergency Service on 0800 111 999.

Gas leaks are an emergency and must be dealt with immediately.

4. Find the reset button

Locate the reset button on your boiler. The reset button is usually found on the control panel, but its location can vary depending on the make and model of your boiler. 

For example, Vaillant boilers have a dedicated reset button, while Worcester and Baxi boilers may have slightly different reset instructions. 

Refer to your boiler manual for the exact location of the reset button.

5. Press the reset button

Press and hold the reset button for about 10 seconds. If the button is recessed, you may need to use a flathead screwdriver. 

Release the button and wait for the boiler to go through its reset sequence. 

You should hear the boiler start up again, and the display screen should show a normal operating status.

6. Observe the boiler

After resetting, observe the boiler for a few minutes to ensure it is working properly. 

Check that the boiler light is green (indicating normal operation) and that no fault codes are displayed. 

Listen for any unusual noises that might indicate ongoing issues.

When to contact a JustFix heating and gas engineer

While resetting your boiler can often resolve minor issues, sometimes it’s best to leave it in the hands of those who know best. 

If your boiler continues to lock out frequently, displays persistent error codes, or if you notice any unusual noises or leaks, it’s important to get professional help. 

At JustFix, our network of engineers can help you with any problem you have around the home. Our prices are fair, and our work is completed correctly the first time. It’s that simple.

Whether you have a combi, system or standard boiler, our engineers can help you with boilers from most major manufacturers, including:

• Baxi boilers
• Ideal boilers
• Worcester Bosch boilers
• Heatline boilers
• Viessmann boilers
• Vaillant boilers
• Navien boilers

The cost of a heating and gas engineers

If your boiler needs immediate attention, a fully qualified JustFix heating and gas engineer costs only £110 + VAT per hour.

Some providers charge more based on location, boiler type, and demand, but this isn’t how we work at JustFix. 

When you book a heating and gas engineer with us, you know exactly what you’ll be paying in advance, so there are no surprises or hidden costs to worry about.

FAQs about how to reset a boiler

Can I reset my boiler myself?

Yes, you can reset your boiler yourself, and it is often a simple process. 

Most modern boilers come equipped with a reset button that you can press to restart the system. Before attempting to reset, it’s essential to identify the reason for the lockout by checking the error code displayed on the control panel. Consult your boiler manual for specific reset instructions for your model. 

For most models, you will need to press and hold the reset button for about 10 seconds. If the boiler continues to lock out or display fault codes, it’s advisable to call a gas-safe registered engineer to investigate further.

How do I restore the pressure on my boiler?

Restoring the pressure on your boiler involves adding water to the system to bring the pressure within the normal range, usually between 1.0 and 1.5 bar. 

First, locate the pressure gauge on your boiler to check the current pressure. If the pressure is low, you will need to find the filling loop, which is typically a flexible silver hose with two valves. Open both valves to allow water into the system, and monitor the pressure gauge. Once the pressure reaches the desired level, close the valves tightly. 

Always refer to your boiler manual for specific instructions on how to safely restore pressure to your particular model.

Why is my boiler not firing up fully?

If your boiler is not firing up fully, several issues could be causing the problem. Common reasons include low water pressure, a faulty ignition lead, a blocked heat exchanger, or a problem with the gas supply. 

First, check the boiler pressure and ensure it is within the normal range. If the pressure is correct, inspect the display screen for any error codes and refer to your boiler manual for troubleshooting tips. If there are no visible issues, the problem could be due to a faulty pump or a blocked plate heat exchanger, which will require the expertise of a gas-safe registered engineer to diagnose and repair.