Before you call anyone, there are a few things worth checking. They are safe, they take five minutes, and they solve a surprising number of the no-heat calls we get. If you smell gas, do not do any of this: leave the light switches alone, open the windows, get everyone outside and call the National Gas Emergency number on 0800 111 999. Then call us.
1. Is the boiler getting power?
Look at the display. If it is blank, check the switched fused spur next to the boiler is on, check the consumer unit for a tripped switch or RCD, and check that a plug-in timer or smart control has not lost power. If a switch has tripped, reset it once. If it trips again, leave it off and call us, because something on the boiler circuit has a fault.
2. Is the thermostat calling for heat?
Turn the room thermostat up above the current room temperature and listen for the boiler starting. Replace the batteries in a wireless thermostat even if it looks fine: low batteries are the single most common cause of a boiler that will not come on. Check the programmer or app is set to on rather than off or holiday mode, and check that a smart thermostat is connected to the internet if it needs to be.
3. What does the pressure gauge say?
Most modern boilers need the pressure to be between 1 and 1.5 bar when cold. If the needle or display shows under 0.5 bar the boiler will not run. Top up using the filling loop (usually a small braided hose or a lever under the boiler) until the gauge reads about 1.2 bar, then close the loop fully. If you have to do this more than a couple of times a year the system is losing water, and that needs looking at.
4. In freezing weather, check the condensate pipe
A condensing boiler drains a small flow of water through a plastic pipe, and if that pipe runs outside it can freeze in a cold snap. The boiler then blocks and shows an ignition or flame fault. Pour warm (not boiling) water along the outside pipe, or hold a hot water bottle against it, until the ice clears, then reset the boiler. If it freezes every winter we can re-route or insulate the pipe.
5. Is gas getting to the boiler?
Try the gas hob. If it does not light, the problem is the gas supply rather than the boiler. Check the emergency control lever at the meter is on (in line with the pipe), check a prepayment meter has credit and has not run out of emergency credit, and ask a neighbour whether the supply in the area is off.
6. Reset the boiler once
Every boiler has a reset button or a reset position on the dial. Press it once and give the boiler a minute. If it fires and stays running, keep an eye on it. If it locks out again, do not keep resetting. Repeated resets can hide a fault and, on some boilers, lock it out completely. Note the fault code on the display and call us.
7. Look up the fault code
Modern boilers tell you what is wrong. Baxi codes start with E (E133, E119, E110), Worcester Bosch use letters and numbers (EA, E9, CE 207), Vaillant and Glow-worm use F codes (F.22, F.28, F.75) and Ideal use F and L codes (F1, L2). Our boiler fault code library on this site explains each code, what you can safely check and whether it needs an engineer.
What not to do
Do not remove the boiler case, touch the gas valve, fan, flue, PCB or heat exchanger, or attempt to clear a flue. All of these are Gas Safe jobs and it is illegal, as well as dangerous, for anyone who is not registered to work on them. Do not keep topping up a boiler that keeps losing pressure, and do not run a boiler that is leaking water onto electrical parts.
Then call us
Essex Heating Engineers repairs all makes of gas boiler across Basildon and south Essex, with a 24-hour emergency line on 01268 855605. Tell us the make, the fault code and what you have already checked, and we will bring the likely parts with us.
Questions
My boiler gives hot water but no heating. What is wrong?
Check the thermostat batteries and the programmer first. If those are fine, the usual causes are a stuck diverter valve inside a combi, or a failed motorised valve or pump on a system with a cylinder. These are engineer jobs.
How many times can I reset the boiler?
Once. If it locks out again there is a fault that a reset will not fix, and repeated resets can make some faults worse. Note the code and call us.
Should I switch the boiler off if it is leaking?
Yes. Switch it off at the fused spur, particularly if water is dripping near electrical parts, make sure the filling loop is closed, put a bowl under the leak and call us.
Does it help if I tell you the fault code?
Very much. The code tells us where to look and which parts to bring, so we can usually fix the boiler on the first visit.
Written by Essex Heating Engineers Ltd, Gas Safe registered 925538, Basildon. Prices quoted are our own published starting prices and are checked when this page is updated.
