Boiler problems: how to avoid a meltdown during a boiler breakdown

Boiler not working? Here are some common boiler problems and solutions to try.

27 June 2019

fire-place Boiler problem
In the home

Key steps

In the event of a boiler breakdown:

  • Check whether the boiler is receiving power.
  • Check the boiler settings and thermostat.
  • Check the pressure and re-pressurise if necessary.
  • Reset the boiler.
  • If all else fails, call a registered engineer.

Boiler not working? It’s a problem we all run into. When you’re faced with a boiler breakdown, don’t despair! Sometimes, some simple boiler troubleshooting is all you need to get the heating back on. Here are some common boiler problems and solutions.

If you don’t have your boiler manual, check the manufacturer’s website! Many boiler manufacturers have manuals for their products available online.

Boiler troubleshooting: first steps

At the first sign of problems, try these steps:

  1. Look-up the error code. Is the boiler displaying some sort of error message or code? If so, check the manual to find out what it means and how you should act.
  2. Check it’s switched on. If the boiler has a display screen, check to see if it is blank. If so, the boiler may not be receiving any power. Is the boiler switched on? Check your home’s fuse box and switch any tripped breakers back to the ‘on’ position.
  3. Make sure you’re in credit. If you have a prepaid gas meter, make sure you’ve remembered to top it up.
  4. Adjust your settings. If the boiler is producing hot water but no central heating, check your boiler settings. Your thermostat may be set too low for the heating to kick in. It’s also possible you have a timer set, meaning that the heating will only come on at certain times of day.
  5. Top up the pressure. The pressure may be shown on a digital display or a dial on your boiler. It should usually be somewhere between 1-2 bar (the ideal range for your boiler will probably be marked in some way). If the pressure is below 1 bar, the boiler may be struggling to circulate hot water properly. See our below for advice on re-pressurising your boiler.
  6. Reset it. If you can’t work out why the boiler stopped working, try resetting the boiler.
  7. Call in the experts. If all else fails, call in experts to check your boiler. Make sure they are Gas Safe registered for safety.

Boiler troubleshooting: re-pressurising the boiler

If your boiler stopped working because the pressure fell below 1 bar, you’ll probably need to re-pressurise it. Before doing this, you need to work out why the pressure dropped:

  • Check for damp spots around your radiators. Low pressure could be the result of a leak, in which case you’ll continue to lose pressure even if you re-pressurise the system. 
  • You may also have low pressure if you’ve bled the radiators recently so always check the pressure after bleeding any radiator. Check out our guide for tips on flushing your radiators correctly.

Once you’ve established why your boiler lost pressure and fixed any problems like leaks, it’s time to top it up:

  1. Switch off the boiler and leave it for a while; don’t attempt re-pressurising while it’s still hot.
  2. If the filling loop isn’t attached, you’ll need to screw it securely onto the mains cold water pipe at one end and the boiler intake at the other. You may need to unscrew caps from the connections first.
  3. Open the valves on both ends of the filling loop. These will usually be opened with a quarter turn of either a built-in handle or a flat-head screwdriver. The pressure on the gauge should start to climb, and you’ll also hear the water being transferred.
  4. If the ideal pressure range is marked on the gauge, close the valves around the middle of the ideal range.
  5. If the ideal pressure range is not marked on the gauge, close the valves around the 1.5 mark.
  6. Make sure the pressure has stopped climbing. If it’s still going up, the valves may not be closed properly.
  7. Switch the boiler back on.

If your boiler is still giving you trouble, it’s probably time to call in a qualified engineer to sort out your boiler problems. Boiler troubleshooting is one thing, but you shouldn’t attempt major boiler repairs yourself.

Check your boiler manual to see if it has specific advice for pressure problems. Most boilers will allow you to replenish the pressure by adding more water into the system via a filling loop. This is a short, flexible silver hose usually found underneath or near the boiler.