If your boiler isn’t firing up, it’s essential to find out why. There could be several different reasons, some of which you may be able to fix yourself.

However, if the problem persists, it may be time to call in the professionals. Your boiler is the heart of your home, and keeping it in tip-top condition is important, so it is essential to take quick action at the first sign of a problem.

In this guide, we’ll go over some of the most common reasons your boiler might not be firing up, as well as some tips on how to fix them. Keep reading to learn more!

A Blocked Burner

If your boiler’s burner is blocked, it won’t be able to fire up. This could be due to several factors, including dirt or soot buildup in your burner chamber and fuel pipework. To fix this problem, you can take the following steps:

  1. Start by turning off the power to your boiler and removing the front panel.
  2. Use a brush or vacuum to remove debris from the burner.
  3. Once the burner is precise, reassemble your boiler and turn the power back on. If your boiler still doesn’t fire up, another problem may occur.

In this case, you should call a professional to come and fix your problem for you. Never take chances with your boiler; you could end up with a faulty unit that could cost a lot of money to repair in the long run.

A Defective Fan

Your boiler needs a fan to circulate air and help the combustion process. If the fan is not working correctly, it could prevent your boiler from firing. To test whether or not the fan is working, hold a piece of paper up to the exhaust pipe while the power is on. If the paper flutters, the fan is working, and you likely have another problem with your boiler. If the paper does not flutter, the fan is not working, and you’ll need to replace it.

To replace the fan yourself:

  • First, turn off the power to your boiler and remove the front panel.
  • Next, disconnect the fan wires from the terminal block on the circuit board. Remove the screws securing the terminal block to the circuit board, and remove the terminal block completely.
  • Finally, replace the fan with the one that comes with your new replacement fan kit. Then reconnect the wires to the terminal block and secure the terminal block to the circuit board with the screws you removed earlier.

Turn the power off and reassemble your boiler. If your new fan works as the old one did, you’re good to go! If not, you may need to call a professional to replace the fan.

You Have a Faulty Gas Valve

If you have a natural gas boiler, it won’t be able to fire up if the gas valve is turned off or set too low. To check if this is the problem, look at the gas valve and ensure it’s in the “on” position. You should also check that the knob is in the correct position for your gas type (natural or propane).

If both things are in order and your boiler won’t fire up, another issue may be at play. If you are unsure, you should call a professional to come and inspect your system. Again, never take chances with your safety.

Your Pipes Are Frozen

If your pipes are frozen, that can prevent water from flowing into your boiler; without water, your boiler can’t operate. To thaw frozen pipes:

  1. Start by turning off your water supply and opening all of the faucets in your home (this will release any pressure buildup in the pipes).
  2. Apply heat to the frozen section of the pipe using a hair dryer, space heater, or heated towel rail.
  3. Once thawed, turn your water supply back on and check for leaks. If everything looks good, try firing up your boiler again.

If it still doesn’t work, you may need to call a professional to fix it. Frozen pipes can be very dangerous, so make sure you’re aware of the warning signs of frozen pipes and what to do if you notice any!

The Pilot Light Has Disappeared

If you have an older model of a gas boiler with a pilot light, that light must be lit for the boiler to operate. If it’s gone out, relight it following the instructions in your boiler’s manual. Once relit, try firing up your boiler again. If it still doesn’t work, the problem may be more serious, and you may need to call in a professional to fix whatever is causing the pilot light to go out in the first place.

With any luck, you’ll be able to get your heater up and running in no time!

Poor Boiler Pressure

Poor boiler pressure refers to how much water is flowing through your system, and if that pressure is too low, it can prevent your boiler from firing up.

To check your system’s pressure, look for a pressure gauge on your boiler (it will likely be located near where the piping comes into contact with the unit). The needle on this gauge should fall between 1 and 2 bars when working correctly. If it falls below 1 bar or above 2 bars when you’re checking it, you have low or high pressure, respectively, and will need to adjust accordingly. To do so, follow the instructions in your manual for adding or releasing water from your system until the needle falls within that normal range (1-2 bars).

Once you’ve done that, try firing up your system to see if it works properly. If it doesn’t, you may need to get your system checked further by a professional to make sure everything is working properly.

Trapped Air Is Blocking Your Heating System

If your boiler is not firing up, it could be due to trapped air in the system. To fix this problem, you’ll need to bleed your radiators. This can be done by turning on your heating and finding the bleed screw on each radiator.

When you locate the bleed screw, crank it counterclockwise until water drips if you notice water dripping, tighten the screw by turning it counterclockwise. For each radiator in your home, you might need to repeat this procedure. Once the bleed screws are tight, turn off your heating and check for leaks. If nothing appears to be leaking, switch on your heating and check to see if it functions as intended.

If it doesn’t, you may need to call in a professional to look at your system to ensure there aren’t any other issues that may be causing your problems.

There’s an Electrical Fault

If there is an electrical fault with your boiler, it will usually display an error code on the control panel. If you see an error code, you should turn off your boiler and contact a Gas Safe-registered engineer for assistance.

If you have an older boiler, you might not have the luxury of having an error displayed on a panel; in that case, you will need to check your instruction manual to try and find out what might be wrong with your model. Once you’ve found the error, you should contact an engineer to come out and repair the faulty component as soon as possible.

Never attempt to repair an electrical fault yourself; it could put you in danger or cause further damage to components already damaged. Always play it safe and take the advice of a professional!

Your Thermostat Is Too Low

If your boiler is not firing up, it could be because your thermostat is set too low. To fix this problem, turn up the thermostat and wait for the boiler to kick in. The heating may take several minutes to kick in, so be patient!

Once the heating has kicked in, reset the thermostat to its original setting and try turning it on and off again to see if the error persists. If it does, you’ll need to contact a Gas Safe-registered engineer to investigate further. Don’t try to fiddle around with the thermostat yourself; that’s a job best left to the experts!

Your Fuse box Has Tripped

If your fuse box has tripped, it will usually be due to a power surge. To fix this problem, reset the switch on your fuse box. If the problem persists, contact a qualified electrician for assistance.

If you attempt to fix the fuse yourself without the proper knowledge, you could damage the fuse or create another fault, which could further damage your home. A professional should be able to run some tests and tell you exactly what’s wrong with your system in no time!


Finally, if the preceding steps do not resolve your problem, you should have your system inspected by a qualified, Gas Safe-registered engineer. It is highly advised that you call a professional to help fix whatever may be causing the issue, as an amateur repair job could cause further damage to your home or even put you and your family in danger!

If you’re experiencing any of the mentioned issues, don’t panic! We’re here to help. All you need to do is contact us, and one of our experts will be more than happy to assist you in diagnosing and fixing the problem with your boiler. Thanks for reading, and have a great day!