How to Reset a Boiler: Quick & Easy Guide

To reset a boiler, you will need to locate the reset button and hold it down for a few seconds to trigger a fresh start cycle. 

How to Reset a Boiler 

The location and method of the reset button varies between boiler brands and models, but the process is broadly the same across all modern central heating boilers.

1. Locate the reset button on your boiler. On most boilers, it is labelled “Reset” and may be a physical button, a dial you turn and hold, or a digital option in the menu. Common boiler brands and their reset methods include:
   • Worcester Bosch: Press and hold the reset button (flame symbol) for 3 seconds
   • Vaillant: Turn the mode dial to the reset position and hold
   • Baxi: Press and hold the reset button for approximately 10 seconds
   • Ideal Boilers: Press and hold the reset button for 3 seconds
   • Viessmann: Use the display menu to select the reset option
2. Hold the reset button for the required time (usually 3 to 10 seconds).
3. Release the button and wait. The boiler will attempt to ignite.
4. You may hear a clicking sound as the boiler tries to fire up, followed by the sound of the burner igniting. This is completely normal.
5. The display should show normal operating symbols or go back to showing the current temperature.
6. Wait two to three minutes to confirm the boiler has fully restarted and is heating correctly.
   Safety Caution: If your boiler does not restart after two reset attempts, stop. Repeatedly resetting a boiler that is not firing can cause further damage. At this point, it is time to contact a Gas Safe registered engineer.

Specific Boiler Issues That Require a Reset

It helps to know if certain issues have led to you needing to reset your boiler. You will need to identify the fault. Before you begin, it is important to have a few basic tools to hand, including your boiler’s user manual, a pressure gauge key, and a torch, and to take a few simple safety precautions to make sure the process goes smoothly.

Step 1. Tools You Will Need to Reset Your Boiler

Before starting a boiler reset, having the right tools to hand makes the whole process quicker, safer, and more effective.

Here is what you should have ready:

1. A torch or your phone’s torch function (boilers are often in dark cupboards or utility rooms)
2. A flat-head or crosshead screwdriver (some boiler panels are screwed shut)
3. A pressure gauge key or radiator bleed key (in case low pressure is the issue)
4. The boiler’s user manual (invaluable for locating the reset button and reading fault codes)
5. A jug of warm water (useful if a frozen condensate pipe is the cause of the lockout)
6. A pen and paper or your phone to note down any fault/error codes displayed on the boiler

Safety Caution: Before you touch your boiler, make sure you are working in a dry environment. Never attempt a boiler reset if you can smell gas. If you suspect a gas leak, leave the property immediately, do not use any electrical switches, and call the National Gas Emergency Service on 0800 111 999.

Step 2: Check for a Fault Code or Error Code

The next step in the reset process is to check whether your boiler is displaying a fault or error code on its digital display panel.

Modern gas boilers, whether combi, system, or conventional, are designed to tell you exactly what has gone wrong. Understanding your boiler’s fault code saves you time and prevents you from simply resetting a boiler that has a deeper underlying issue.

1. Look at your boiler’s display panel or control screen.
2. Write down any letters or numbers being displayed (e.g. E1, F22, EA 338, 0E, etc.).
3. Cross-reference the fault code with your boiler’s user manual.
4. If you do not have the manual, search for your boiler brand and model number online along with the fault code (e.g. “Worcester Bosch fault code EA 338”).
5. Common fault codes point to low pressure, ignition failure, a frozen condensate pipe, or an overheating issue.
6. Once you know the cause, you can address it before attempting the reset, which significantly increases the chance of a successful restart.
   Safety Caution: Do not ignore or dismiss fault codes. They are your boiler’s way of flagging a safety concern. If the fault code indicates a gas-related issue or carbon monoxide risk, do not attempt a reset and contact a Gas Safe registered engineer immediately.

Step 3: Check Your Boiler’s Water Pressure

Low boiler pressure is one of the most common reasons a boiler locks out and needs resetting. Checking the pressure gauge should be done before every reset attempt.

The pressure gauge is typically located on the front of the boiler, either as a physical dial or a digital reading on the display. Most boilers need to be within a specific pressure range to operate safely.

1. Locate the pressure gauge on your boiler (it is usually on the front panel or display screen).
2. The ideal boiler pressure for most central heating systems when cold is between 1 bar and 1.5 bar.
3. If the pressure reads below 1 bar, your boiler pressure is too low and will need to be topped up (re-pressurised) before the reset will work.
4. To repressure the boiler, locate the filling loop (a silver or grey braided hose usually found underneath the boiler).
5. Slowly open the valves on the filling loop until the pressure gauge reads approximately 1.2 to 1.5 bar.
6. Close the filling loop valves securely once the correct pressure is reached.
7. If the pressure reads above 3 bar, it is too high. Do not attempt a reset. In this case, you should bleed a radiator to release some pressure or contact an engineer.
   Safety Caution: Never over-pressurise your boiler. If pressure keeps dropping shortly after topping up, this indicates a leak somewhere in the heating system and you should contact a qualified engineer rather than repeatedly re-pressurising.

Step 4: Check the Thermostat and Timer Settings

Before attempting a reset, it is worth checking that the issue is not simply an incorrect thermostat or timer setting, which is a surprisingly common and easily overlooked cause.

Boiler problems are not always mechanical. A thermostat set too low or a programmer that has been accidentally changed will prevent your boiler from firing up, even if it is in perfect working order.

1. Check your room thermostat and confirm it is set above the current room temperature (try setting it to at least 21°C to test).
2. Check your boiler’s programmer or timer to confirm it is set to “heating on” and that the schedule is correct.
3. If you have a smart thermostat (such as a Hive, Nest, or Tado), check the app to confirm it is calling for heat.
4. If your thermostat or timer settings look correct, move on to the next step.
5. If adjusting the thermostat immediately causes the boiler to fire up, the boiler itself did not need resetting at all.
   Safety Caution: If you have a smart thermostat that has lost its Wi-Fi connection, it may not be communicating with the boiler correctly. Restart your router and the thermostat before assuming a boiler fault.

Step 5: Check the Condensate Pipe (Especially in Cold Weather)

During cold snaps, a frozen condensate pipe is one of the most frequent causes of boiler lockouts across the UK, particularly from October through to March.

The condensate pipe is a white plastic pipe that carries wastewater from a condensing boiler to an external drain. Because part of this pipe is outside, it can freeze in temperatures at or below 0°C, causing the boiler to shut down as a safety measure.

1. Locate the condensate pipe. It is usually a white plastic pipe (about 21mm or 32mm in diameter) that exits through an external wall or goes through the floor.
2. Look for signs of ice or frost on the pipe, especially near joints or bends.
3. To thaw a frozen condensate pipe, pour warm (not boiling) water along the pipe, starting from the outlet end and working back towards the boiler.
4. Alternatively, you can wrap a hot water bottle or a warm cloth around the frozen section of the pipe.
5. Never use boiling water or a heat gun, as this can crack the pipe.
6. Once the pipe is thawed, the boiler should accept a reset.
   Safety Caution: After thawing the condensate pipe, check for any visible cracks or splits before proceeding. A cracked condensate pipe will need to be repaired or replaced by a qualified engineer before you attempt a reset.

Step 6: Bleed Your Radiators (If Needed)

If your boiler has reset successfully but the radiators are not heating up evenly, or some are cold at the top, trapped air in the system may be the cause.

Bleeding your radiators is a simple maintenance task that removes air pockets from the central heating system, allowing hot water to circulate freely and improving efficiency.

1. Turn your heating on and allow the radiators to warm up for about 10 minutes.
2. Identify which radiators are cold at the top but warm at the bottom. This is the classic sign of trapped air.
3. Turn the heating off and let the system cool slightly before bleeding.
4. Use a radiator bleed key (or a flat-head screwdriver on some modern radiators) and insert it into the bleed valve at the top corner of the radiator.
5. Slowly turn the key anti-clockwise by about half a turn until you hear a hissing sound. This is air escaping.
6. Hold a cloth or small container under the valve to catch any water.
7. Once water starts to flow steadily (no more hissing), turn the key clockwise to close the valve.
8. Repeat this process on all affected radiators.
9. After bleeding, check the boiler pressure again and top it up if it has dropped below 1 bar.
   Safety Caution: Do not fully unscrew the bleed valve. A quarter to half a turn is all that is needed. Fully removing the valve can cause a sudden rush of hot water.

Step 7: Check the Boiler’s Pilot Light (Older Boilers)

If you have an older gas boiler rather than a modern condensing boiler, the issue may be a pilot light that has gone out.

Most boilers installed after 2005 do not have a traditional standing pilot light, but if your boiler is older, checking the pilot light is an important step in the reset process.

1. Check your boiler manual for the pilot light location and re-ignition instructions, as these vary by model.
2. If the pilot light is out, follow the manufacturer’s instructions to re-light it. This typically involves:
   • Turning the gas control valve to the pilot position
   • Pressing and holding the ignition button
   • Holding the gas control button down for around 30 seconds before releasing
3. If the pilot light will not stay lit, the thermocouple (a safety device that keeps the gas valve open) may have failed.
4. A faulty thermocouple needs to be replaced by a Gas Safe registered engineer.
5. If the pilot light relights successfully, turn the control valve to the “on” position and the boiler should restart.
   Safety Caution: Never attempt to dismantle or repair any internal gas components yourself. Gas work must always be carried out by a Gas Safe registered engineer. It is illegal and extremely dangerous for anyone without the correct registration to carry out gas work in the UK.

Step 8: Call a Gas Safe Engineer If the Problem Persists

If you have worked through all of the steps above and your boiler still will not reset or keeps locking out, the issue is likely more than a simple fix.

Some boiler problems genuinely do require the expertise of a qualified engineer. Knowing when to stop and call for professional help is just as important as knowing how to carry out a reset.

1. Do not attempt more than two reset cycles on a boiler that is not firing.
2. Contact a Gas Safe registered engineer if:
   • The boiler keeps tripping out shortly after being reset
   • You can smell gas at any point
   • The fault code indicates a gas pressure or combustion issue
   • There are visible signs of damage, corrosion, or leaks around the boiler
   • The boiler is making loud or unusual noises
3. When booking an engineer, provide them with the fault code displayed and a brief description of what you have already tried.

Safety Caution: Carbon monoxide is a silent and odourless killer. If your carbon monoxide alarm sounds at any point, leave the property immediately, leave doors open as you exit, and call the National Gas Emergency Service on 0800 111 999.

Does Resetting a Boiler Fix All Faults?

Resetting a boiler does not fix all faults, but it does successfully resolve the majority of minor, temporary lockout situations.

A reset clears the boiler’s error memory and attempts a fresh start cycle. It works best when the original cause of the lockout, such as a frozen condensate pipe, temporary low pressure, or a brief power interruption, has already been resolved. However, there are faults that a reset will never fix:

• Mechanical failures such as a broken pump, motorised valve, or diverter valve
• Electrical component failures, including printed circuit board (PCB) faults
• Gas supply problems or issues with gas pressure at the meter
• Significant limescale or sludge build-up restricting water flow
• Heat exchanger damage or corrosion

If your boiler displays the same fault code every time it locks out, that is a strong indicator that a physical repair is needed rather than a reset.

How Often Should You Reset a Boiler?

Resetting a boiler occasionally is completely normal, but you should not need to reset your boiler on a regular basis.

If your boiler is tripping out and needing a reset more than once or twice over a short period, this is a sign that something underlying is causing repeated lockouts. The boiler’s safety mechanisms are doing their job and shutting the system down to prevent damage or danger. Common reasons for frequent lockouts include:

• Persistent low pressure due to an undetected leak
• Limescale or sludge build-up inside the heat exchanger, which is common in hard water areas of the UK such as London, the South East, and the Midlands
• A faulty ignition electrode or spark igniter
• Blocked or incorrectly routed flue, preventing safe combustion gases from escaping
• An ageing boiler that is approaching the end of its working life (typically 10 to 15 years)

A regular annual boiler service is the single most effective way to prevent unnecessary lockouts. A qualified engineer will clean key components, check for early warning signs of wear, and keep your boiler running efficiently all year round. Annual maintenance for home boilers is essential for prolonging the life of your heating system. It not only ensures that everything is functioning correctly but also helps identify potential issues before they escalate into more significant problems. By scheduling regular check-ups, homeowners can enjoy peace of mind and maintain a comfortable living environment throughout the colder months. There are several types of boilers for UK homeowners, each designed to meet different needs and preferences. Understanding the advantages of combinations, system, and conventional boilers can help in making an informed decision. Consulting with a heating specialist can ensure that you choose the best option for your specific requirements.

Is Your Boiler Covered When It Breaks Down?

A boiler reset can fix a lot of minor issues, but what happens when the problem is more serious? A failed heat exchanger, a broken pump, or a faulty gas valve can leave you facing repair bills of anywhere between £300 and £2,000 or more. That is where having a boiler cover plan in place makes a real difference. A boiler replacement cost analysis can help you understand the financial implications of a new system. It is essential to consider not only the initial outlay but also the long-term savings from increased efficiency. Evaluating your options thoroughly will ensure that you make an informed decision that suits your budget and heating needs.

PlusHeat offers flexible boiler cover plans starting from just £4.99 per month, giving UK homeowners and landlords complete peace of mind that whenever a boiler problem strikes, a Gas Safe registered engineer will be on their way. Plans include a free annual boiler service (worth up to £120), priority 24/7 emergency support, and full parts and labour cover, so there are no nasty surprises on your bill.

Frequently Asked Questions

Can I reset my boiler if I have a prepayment meter and my gas has run out?

Yes, but the reset will not work until your gas supply is restored. If you have a prepayment (pay-as-you-go) gas meter and your credit has run out, the boiler will lock out because there is no gas reaching it. Top up your meter first, then follow the reset process. 

Some meters also have an emergency credit facility that can be activated through the meter itself.

Will resetting my boiler affect my hot water as well as my heating?

Yes, on a combi boiler a successful reset restores both central heating and hot water because both functions are managed by the same unit. On a system boiler with a separate hot water cylinder, a reset restores the boiler’s function but the hot water cylinder may take some time to reheat. Check the cylinder thermostat is set correctly (usually between 60°C and 65°C) if hot water is slow to return after a reset.

Is it safe to reset a boiler at night or early in the morning?

Yes, it is perfectly safe to reset your boiler at any time of day, provided you have ruled out a gas leak or any other safety concern first. The reset process itself does not carry any timing risk. 

However, if the lockout was caused by a frozen condensate pipe, it is worth waiting until daylight so you can properly inspect the external pipe before and after thawing it.

How long does a boiler reset take before the heating comes back on?

After a successful reset, most boilers will fire up within a minute and you should begin to feel warmth from radiators within 15 to 30 minutes, depending on the size of your property and the outdoor temperature. If the boiler has fired up but radiators are taking much longer than expected to heat, check for airlocks by bleeding the radiators as described in Step 6.

Can resetting a boiler too many times cause damage?

Yes, resetting a boiler repeatedly in a short period can cause damage, particularly to the ignition electrodes and the PCB (the circuit board that controls the boiler). Most modern boilers have a built-in lockout mechanism that will prevent the boiler from attempting to fire if it has failed to ignite several times in a row. 

This is a safety feature, not a fault. If your boiler has gone into a hard lockout, a Gas Safe engineer will need to attend to investigate and clear it manually.