Facebook pixel
new boiler

Get a new boiler

Fixed price boilers, next day

See boiler prices
new air conditioning

Air Conditioning

Get a quote
new heat pump

Heat Pumps

Coming soon

new ev charger

EV Chargers

Get a quote
boiler servicing

Boiler Servicing

Get a quote

Last updated: 7th May, 2024


Why Won't My Boiler Turn On?

Why Won't My Boiler Turn On?

Key takeaways

  • A non-functioning boiler can be caused by various issues, from simple power supply interruptions to more complex mechanical faults.
  • Initial troubleshooting includes checking the boiler's power supply, gas valve, and fan, as these are common points of failure.
  • Regular maintenance and seeking professional advice are essential to ensure your boiler operates reliably and to prevent future breakdowns.

Boilers are complex systems, and pinpointing the exact reason for failure can sometimes be a challenging task that may require professional intervention. Regular maintenance and keen observation of your boiler's performance are essential in preventing unexpected malfunctions.

Experiencing a boiler breakdown can be a significant inconvenience, leaving one without central heating and hot water, especially during times of cold weather. 

A boiler not firing up is a common domestic issue that many encounter, and understanding the potential causes is the first step towards resolution. From power supply issues to a faulty gas valve, there could be myriad reasons for a boiler's failure to turn on, each requiring a different approach to troubleshoot effectively.

Need a new boiler?

Get a quote in 60 seconds, fitted as fast as next day!
0% APR finance available.

Get a quote

Boilers are complex systems, and pinpointing the exact reason for failure can sometimes be a challenging task that may require professional intervention. Regular maintenance and keen observation of your boiler's performance are essential in preventing unexpected malfunctions. 

Aspects such as checking the power supply, assessing the functionality of the boiler fan, and monitoring the gas pressure can provide early indications of potential problems.

Common Causes of Boiler Failures-

Identifying the root cause of a boiler failure can be challenging due to the complexity of the system. Issues may range from electrical problems to complications within the water system.

Electrical Issues

In many cases, power supply problems impact a boiler's ability to function properly. A power cut or a tripped fuse can prevent a boiler from igniting, rendering it inoperable. It is important to check the fuse box and ensure that all fuses relevant to the boiler are switched on. Additionally, damaged wired connections can affect electricity flow, so inspecting these is also a step worth considering.

Gas Supply Problems

A boiler that won't ignite might be experiencing gas supply issues. A faulty gas valve or no gas supply at all can halt operations. The gas meter and other gas appliances should be inspected for consistency in supply. If the boiler's gas valve is not functioning correctly, despite an adequate gas supply, it may not allow gas into the boiler, which is required for combustion.

Pressure Related Issues

Water pressure fluctuations have a significant impact on boiler operations. A boiler may display an error code relating to pressure gauge readings; if the pressure is too low, it may need to be repressurised. Loss of pressure, potentially from a leak or because the system was not repressurised properly after bleeding radiators, can lead to failure.

Water System Complications

Finally, the boiler's own water system can be a source of trouble. Corrosion and blockages in pipes can prevent adequate water flow. Regularly checking for signs of corrosion or leaks can pre-empt these problems. If the pressure gauge indicates high pressure, it might be a sign of a blockage or other complications within the water system.

Assessing Boiler Components

Timely maintenance and regular boiler services are essential for the ongoing functionality of a boiler's components. When a boiler fails to ignite, a systematic evaluation of crucial parts can identify the cause of ignition failure.

Pilot Light and Burner Evaluation

The pilot light, if present in older boilers, is a small flame that ignites the burner. If the pilot light has extinguished, it may need relighting according to the manufacturer's instructions. Conversely, in modern condensing boilers, electronic ignition systems have replaced pilot lights. For these, securing a professional boiler service may be necessary to resolve more complex ignition issues.

Thermostat Checks

A faulty thermostat could lead to the boiler not activating the central heating system. Ensure the thermostat settings are correct and that it signals the boiler to initiate heating. If it appears unresponsive or inaccurate, recalibration or replacement by a certified technician may be required.

Examining the Heating System

Radiators lacking warmth can indicate circulation problems within the central heating system. Checking individual radiator valves for proper operation is imperative, and bleeding the radiators may release trapped air, which can restore efficient heating. If the issue persists, a deeper inspection of the boiler's internal components may be in order.

Fan and Flue Inspection

The fan in a boiler aids in expelling combustion gases through the flue. A malfunctioning fan could prevent the boiler from igniting, acting as a safety measure to avoid hazardous gas build-ups. Conduct an auditory examination for any unusual sounds from the fan, as these might signal a fault. The flue, too, requires a clear path for gas to escape; a visual inspection can confirm if blockages are present.

Weather Implications on Boiler Performance

Weather can have a profound impact on the operation and efficiency of boilers. Cold weather conditions, in particular, bring unique challenges that affect both the functionality of the heating system and the integrity of the pipes.

Impact of Low Temperature

Low temperatures can influence a boiler's ability to function correctly, primarily due to the risk of frozen condensate pipes. These pipes are crucial as they carry condensation away from the boiler to a drain outside the house. During severe cold snaps, the water in these pipes can freeze, leading to blockages that can cause the boiler to shut down as a safety precaution. Thawing a frozen condensate pipe generally involves applying a gentle heat source, such as warm cloths or a hot water bottle, to the affected area until normal function resumes.

Effect of Cold Weather on Pipes

The effect of cold weather on boiler pipes extends beyond the condensate pipe. Cold snaps can cause water within pipes to freeze, potentially leading to cracks or bursts. This situation not only disrupts heating but can also cause significant property damage. It is therefore critical to ensure that all pipes are properly insulated, particularly those that are exposed to external conditions. Maintaining a consistent indoor temperature can also help prevent freezing, allowing for uninterrupted heating performance even during the coldest months.

Troubleshooting & Resetting Your Boiler

If your boiler fails to activate, it's prudent to inspect the basics before proceeding with more complex steps. Initially, verify the power supply, checking your consumer unit for any tripped fuses. Ensure all fuses are switched on, and the isolation switch adjacent to the boiler is active.

Subsequent to power verification, one should examine the boiler's pressure levels and ascertain they're within the recommended range. Low pressure may impede the boiler's functionality. If the boiler exhibits an error code, refer to the manual for specific guidance as these codes can pinpoint the exact issue.

Resetting the Boiler:

  1. Locate the Reset Button: This is typically situated near the boiler's display screen. On some boilers, you might find a reset dial instead.

  2. Perform a Reset: For many models, a quick press suffices. Others might necessitate holding the button for several seconds.

Dealing with Boiler Lockout:

Occasionally, a boiler will enter 'lockout' mode as a safety measure when a fault is detected. In such cases, attempting a reset is the first step. If the boiler resumes operations but subsequently locks out again, further investigation is warranted.

Note: Persistent lockout episodes signal the need for professional assessment. They should peruse the system thoroughly, possibly uncovering underlying issues that a basic reset cannot remedy.

In instances where the boiler doesn't respond to a reset, or the issue is beyond the user's comprehension, soliciting the expertise of a qualified engineer is imperative. They are equipped to diagnose and remedy faults beyond the scope of standard troubleshooting measures.

Professional Intervention

When a boiler fails to ignite, it is prudent to seek the expertise of a professional without delay. Addressing boiler issues promptly helps prevent potential accidents and ensures that heating systems operate efficiently and safely.

When to Call a Gas Engineer

If homeowners encounter symptoms such as leaks, strange noises, or a complete lack of heating and hot water, it becomes essential to call in a Gas Safe registered engineer. Here are key scenarios where professional intervention is critical:

  • Gas Leaks: The unmistakable smell of gas or a hissing sound near the boiler could indicate a leak. In such cases, evacuating the premises immediately and contacting an emergency gas engineer is crucial.

  • Carbon Monoxide Alerts: Should a carbon monoxide detector signal high levels of the gas, it is a clear sign to cease using the boiler and get a professional evaluation.

  • Persistent Issues: Recurring problems, despite attempts at troubleshooting, often require the diagnosis and specialised tools of a Gas Safe heating engineer.

  • Safety Inspections: It is advisable to have routine safety inspections conducted by a Gas Safe registered engineer to mitigate the risk of carbon monoxide poisoning and ensure the boiler’s regulatory compliance.

  • No Heat or Hot Water: If basic checks, like verifying the power supply or pressure gauge, do not resolve the issue, the complexity of the system merits a professional's attention.

It is paramount that any engineer working on a boiler is Gas Safe registered, as this certification proves their qualifications to work safely and legally on gas appliances. Homeowners can verify an engineer's Gas Safe credentials to ensure that the individual has the requisite expertise to handle the intricacies of a boiler system.

Maintenance and Prevention

Ensuring your boiler operates efficiently requires dedicated maintenance and preventative measures. Regular checks can avoid many common issues that lead to a boiler not igniting.

Advantages of Regular Boiler Service

Consistency of Performance: A boiler maintained through a scheduled service programme typically exhibits a steady level of performance. Regular cleaning and examination of components like the heat exchanger, burners, and ignition system keep the boiler running smoothly, which can prevent ignition problems before they arise.

  • Safety: During service appointments, engineers check for leaks or damage that could lead to carbon monoxide release or other hazards. This cleaning and inspection routine contributes to the overall safety of one's home.

  • Increased Efficiency: Accumulated dirt and debris can hamper a boiler's effectiveness. Regular cleaning ensures optimal gas combustion, which, in turn, helps to maintain fuel efficiency.

  • Extended Boiler Lifespan: Components within a boiler may wear out less quickly when they are regularly serviced and kept in clean, working order, potentially elongating the boiler's operational life.

  • Cost Savings: Although there's an upfront cost for maintenance, this can lead to savings over time. A well-maintained boiler can preclude the expense of emergency call-outs and the higher costs associated with significant repairs or premature replacement.

Through adherence to a thorough maintenance schedule, one ultimately secures a reliable boiler system, with lowered risks of unexpected failures that could result in a boiler's inability to ignite.

New Boiler Costs

Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.

Effectively, new boiler cost can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer. 

Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.

Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).

Installation Type

Price (inc VAT)

Combi to combi swap


Get a quote

System to combi conversion


Get a quote

New boiler install


Get a quote

Back boiler to a combi


Get a quote

System to system


Get a quote

Frequently Asked Questions

Why is my boiler not turned on?

The failure of a boiler to turn on could be due to issues ranging from no power supply, such as a tripped fuse or circuit breaker, to incorrect thermostat settings. Checking these elements is the first step in troubleshooting.

Why is my boiler not kicking on?

If a boiler isn't kicking on, it could be due to several reasons including interrupted power or gas supply, or a fault with the boiler's internal components like the ignition system. It's essential to confirm that there is active supply and the settings are correct.

How do I fix my boiler not firing up?

To fix a boiler that isn't firing up, check for common problems such as low water pressure, a frozen condensate pipe, or a faulty thermostat. Resolving these issues often requires resetting the boiler or thawing the condensate pipe.

How do you manually ignite a boiler?

Manually igniting a boiler is typically done by pressing the boiler's ignition button, following the manufacturer's instructions. Always exercise caution and if unsure, consult with a registered heating engineer.

Is boiler not working an emergency?

A non-working boiler can be considered an emergency, especially during cold weather, as it affects heating and hot water supply. Vulnerable persons affected by lack of heating should treat boiler issues as urgent and seek professional assistance promptly.

How do I get my boiler to fire up?

To get your boiler to fire up, first ensure that the electrical and gas supplies are functioning. Next, verify that the thermostat and pressure levels are within the recommended range. If the problem persists, resetting the boiler might be necessary.

How do you reset the ignition button on a boiler?

Resetting the ignition button on a boiler involves locating the reset button, often found on the boiler's front panel, and pressing it according to the manufacturer's guidelines. Wait for the boiler to go through its reset process, which may include a delay before it attempts to reignite.

Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.