Why is my boiler not working & how to fix it

inside boiler

If your boiler isn’t working then don’t panic just yet. You may be able to fix it yourself. You may also need a Gas Safe registered heating engineer. The most common reason for a boiler not to work is low pressure or a frozen condensate pipe in winter.

Need a new boiler? Get a quote here in seconds!

Other common problems are no gas or electricity to the boiler, faulty thermostats or controls or if your boiler is old may be breaking down. Even the best combi boilers have an off day, so let’s see if we can help!

Boiler not working – Problems you can fix yourself and how to do it

Here are some of the most common boiler problems that you can fix yourself. These quick fixes could save you money on call-out charges to a gas engineer when it is not needed.

If you are totally unsure, then it may be worth paying. But hopefully, the reason your boiler is not working is one of the following reasons and you can mend it yourself. If your boiler is old you need a new one, you can find out how much a new boiler cost online now.

Check that your boiler is switched on at the mains

plug socket

Before doing anything, ensure that your boiler has power to it. This may be by accidentally switching it off, a fuse blowing, or a power cut. If there is no electricity to your boiler then it won’t work at all.

If this is the case, you may have just found your problem, but if not, and assuming your boiler is switched on and has gas running to it then the following fixes can work right away.

Ensure your gas and utility bills are up to date, or prepayment meter is topped up

If for whatever reason you aren’t up to date with your gas and electricity payments, then suppliers can cut off your supply.

This is a worst-case scenario, so you should be aware that this is happening, if your not you must get in contact with our supplier right away. You have the right to have heating in your home at all times, so hopefully, this is just a quick fix for you.

Quick boiler fixes for common reasons why your boiler won’t work 

These are some of the easiest things to do to get your broken boiler back up and running before calling a heating engineer.

All of these tips should get your boiler back working if it is the reason it is not firing up. If these fixes don’t work, you will need to speak to a plumber and check out the other reasons why further down the page.

inside fixing boiler

Boiler Pressure too low

This is the most ideal problem to have in terms of a quick fix for a boiler not working. All you have to do is top up your low boiler pressure and your boiler will start working again. Once the boiler is at least in the correct range, it will start up again if this is the issue.

How to top up boiler pressure

To top up the boiler pressure you need to find the filing loop underneath your boiler. These will have two valves very close to each other, which you need to open at the same time.

You also need to be able to see your pressure gauge so that when you get to 1.5bar or within the green area on some boilers, you can close the valves. If your boiler has turned off, switch it back on or reset it and it should start to fire up properly. 

If the pressure starts to drop again repeatedly, then you have a leak somewhere in the system and you will need to call an engineer. 

Frozen condensate pipe

frozen condensate pipe

A frozen condensate pipe is a massive reason why people’s boilers don’t work in winter. The excess water that your boiler is producing is freezing when it is getting outside and stopping any more water from escaping, causing your boiler to shut down. 

Fixing a frozen condensate pipe

Hot water poured over the condensate pipe outside your home will fix this problem for you instantly. Do not call out an engineer and waste money before checking this issue if it is freezing outside. It is literally a 2-minute job. 

Boiler thermostat and controls not connected 

Assuming that your boiler is switched on but central heating not coming on, then you may need a new thermostat, or the batteries may need changing.

This is a quick and simple fix you can do yourself. If you change the batteries and it doesn’t work then your thermostat may be broken or the connection at your boiler is faulty. You should see a green light on the receiver at your boiler if it is connecting. If it is, then it is unlikely to be your thermostat. Smart thermostats will tell you if they are not connected too.

Reasons your boiler may not be working that required and heating engineer

These are the situations where your boiler can be fixed but only by a Gas Safe registered heating engineer. All the following will mean that the heating engineer has to open up the boiler to investigate and check the boiler over. It may also mean parts need changing or fixing which are more technical than just topping pressure up.

Boiler leaking water and not turning on

inside combi boiler

If there is water leaking from your boiler fast or slow, then it is likely that you are going to need to call a plumber to fix it. Your boiler may stop working during this time, it may turn itself off or it may be on, but not providing heating or hot water.

There are numerous reasons this could be, such as corrosion, broken seals, or broken heat exchangers.

If you want to know more about water leaks, check out our boiler leaking water guide. Problems like this can cost between £100 and £500, so it may be worth considering a new boiler.  

Boiler won’t turn on and electricity is switched on

If you are confident that your electricity supply is working and your gas is flowing then, you may have a serious internal problem with the electronic parts inside such as a broken circuit board or fuse that has blown internally. If this is the case, expect costs of around £200 to fix at least.

If your boiler is really old, it may be worth thinking about getting a new boiler. Find out how much a new boiler costs here.   

Boiler switched on but no how water

If your boiler is switched on and showing a green light to say that your thermostat is connected, and when you turn your taps on there is no hot water, you likely have a faulty diverter valve stopping hot water from being delivered to your taps.

This is a job for a heating engineer and will require your old diverter valve to be taken out and replaced with a new diverter valve. Again, if you have an old boiler, you need to decide whether it is worth replacing or worth getting a new combi boiler. 

Radiators not getting hot but boiler working

If your boiler is on, getting warm, and providing hot water to your taps, but your radiators are still cold, then you may have a blockage in your radiators.

The best thing to do is check the radiators that get hot water from your boiler first. If they are warm but the ones in other rooms aren’t then you have a blockage and will need either a chemical system flush or a power flush. These do not require a new boiler, but the blockage needs removing so that it doesn’t get in your boiler. 

Boiler not working error codes – what do they mean?

If your boiler is not working then you may be getting an error code. Here are some of the most common boiler error codes for boilers in the UK so you can diagnose the problem quickly and easily. 

viessmann logo error codes

Viessmann Error Codes

These error codes relate to the Vitodens 050, Vitodens 100 and Vitodens 111-w boilers, and more.

Frozen condensate pipeF4 EE
Burner blockageF1
Low PressureCheck Gauge
worcester logo error codes

Worcester Bosch error codes

Error codes for Worcester Bosch boilers you may come across for their Greenstar range such as the Worcester 4000, Worcester 8000, and Worcester 2000 boilers

Frozen condensate pipeD5 EA
Heat Exchanger IssueA1, CE 207, H07, 224V, 1017W, 2970B
Pilot light not firing upEA, F7, FA, EA227, F7 228, FA306
Heat Exchanger error2963 B, 2964 B, 2966 B, 2967 B
Internal Fan FaultC6, T2, C6 215, C7 214, C1 264
vaillant logo error codes

Vaillant Error Codes 

These error codes relate to Vaillant and the Vaillant ecoTEC boiler range

Frozen condensate pipeF28 and F29
Pressure too low/highF.24, F.12, F.22, F.73
ideal logo error codes

Ideal Error Codes

Ideal error code relating to the Ideal Logic boiler range

Frozen condensateLF,F2,L2
Fan not workingF3
Low water pressureF1
PCB (circuit board) errorF9, L9, F8, L8
baxi logo error codes

Baxi Error Codes

Baxi error codes including the Baxi 600 range

Frozen condensate pipee133 e28
CB (circuit board) errorE100, E167, E168, H.02 – 02, 4-5 Green Flashes
Pressure too high/lowE28, E119, 117, 118, 119
Pilot light errorE128, E129, E384

Boiler not working do I need a new boiler?

If you have fixed your boiler or you have called an engineer out, then great. But if you think your boiler may be on the blink or breaking down then you may want to get a quote for a new boiler just to see how much a new boiler costs including installation just in case.

It may save you money in the long run and it may cost less than you think or save your money on repeat call-outs.

Get a Quote in 20 SecondsClick here >