It's a freezing February morning in Farnham, you stumble downstairs for a warm shower, and… nothing. Stone cold water. Your boiler's packed it in again.
We've seen it all over the years working across Farnham, Farnborough, and Guildford. Boilers are brilliant when they work, absolute nightmares when they don't. The good news? Most boiler problems have pretty straightforward causes, and some you can actually fix yourself before calling us out.
This post outlines the 10 most common reasons your boiler stops working and what you can do about them. Some are quick DIY fixes, others need a Gas Safe engineer (that's where we come in). Let's get your heating sorted.
1. Your Boiler Has Lost Pressure
This is the number one culprit we see. If your pressure gauge is reading below 1 bar, your boiler won't fire up properly. It's a safety feature, really – low pressure means there isn't enough water circulating through the system.
The Fix: Most modern boilers have a filling loop underneath. Turn both valves slowly until the pressure gauge reads between 1 and 1.5 bar, then close them again. Dead simple. If the pressure keeps dropping, you've got a leak somewhere and that needs professional attention.
2. The Thermostat Is Playing Up
Sometimes the problem isn't the boiler at all. If your thermostat is set too low, has dead batteries, or is positioned in a sunny spot or near a radiator, it'll tell your boiler everything's fine when your house is actually freezing.
The Fix: Check your thermostat batteries first. Make sure it's set above the current room temperature. Try turning it up a few degrees and listen for the boiler firing up. If nothing happens, the thermostat might need replacing – we can sort that during a service visit.
3. Frozen Condensate Pipe
This is a big one during Farnham winters. Modern condensing boilers have a pipe that carries wastewater outside, and when temperatures drop below freezing, that pipe can freeze solid. Your boiler will shut down to protect itself.
The Fix: You can carefully pour warm (not boiling) water over the external pipe to thaw it. Wrap an old towel around it first. Once it's thawed, your boiler should reset. If this keeps happening, give us a call – we can insulate the pipe or reroute it to prevent future freezing.
4. No Gas Supply
Sounds obvious, but it happens more than you'd think. If you've got other gas appliances that aren't working either, check if your gas meter has been turned off accidentally or if there's an area supply issue.
The Fix: Make sure your gas meter is turned on. If you smell gas at all, don't mess about – turn off the supply, open windows, and call the National Gas Emergency Service on 0800 111 999 immediately. Once it's safe, we can come out and check everything's working properly.
5. Pilot Light Has Gone Out (Older Boilers)
If you've got an older boiler with a pilot light, it can blow out occasionally. No pilot light means no ignition, which means no heat.
The Fix: Check your boiler manual for relighting instructions – it's usually pretty straightforward. If it won't stay lit or you're not comfortable doing it, call a Gas Safe engineer. Sometimes the thermocouple needs replacing, which is a job for professionals like us.
6. Blocked or Dirty Burner
Over time, dust and debris can build up on your burner, preventing proper ignition. This leads to flame failure or the boiler shutting down randomly.
The Fix: This isn't really a DIY job. Gas burners need to be cleaned by a registered engineer during an annual service. If you can't remember the last time your boiler was serviced, that's probably part of your problem right there. Regular maintenance prevents most of these issues – we offer service plans across Farnham that keep everything running smoothly.
7. Airlocks in the System
Air trapped in your heating system can cause all sorts of chaos. Radiators that won't heat up properly, strange gurgling noises, or the boiler cutting out are all signs of airlocks.
The Fix: Bleeding your radiators releases trapped air. Start with the radiators furthest from the boiler, using a radiator key to open the valve slightly until water (not air) comes out. Do this with the heating on. If that doesn't solve it, you might need the whole system power-flushed, which is definitely one for the professionals.
8. Faulty Pump or Diverter Valve
The pump circulates hot water around your system. If it's seized up or failing, your boiler might fire up but the heat won't go anywhere. Same with the diverter valve – if it's stuck, you might get heating but no hot water, or vice versa.
The Fix: You'll hear strange noises if the pump is struggling. Sometimes you can free a stuck pump by gently tapping it (weird but true), but usually these components need replacing. We carry most common pump models on our vans, so we can usually fix this in one visit.
9. Electrical Issues or Tripped Circuit Breaker
Modern boilers are basically computers with a flame attached. If there's a power cut or the circuit breaker trips, your boiler won't work. Sometimes the boiler's internal PCB (printed circuit board) develops a fault too.
The Fix: Check your fuse box first – reset any tripped switches. Make sure the boiler itself is switched on at the spur. If everything looks fine but the boiler's dead, the PCB might have failed. These are expensive but necessary components that need professional replacement.
10. Limescale Build-Up (Especially in Guildford and Farnham)
We've got pretty hard water around here, which means limescale. Over time it builds up in your heat exchanger, reducing efficiency and eventually causing blockages. Your boiler has to work harder, costs more to run, and might start shutting down.
The Fix: Prevention is better than cure – consider installing a magnetic filter or chemical inhibitor during your service. If the damage is done, a power flush can clear the system. In severe cases, the heat exchanger needs replacing. We've done hundreds of these across Surrey – it makes a massive difference to your heating performance.
When to Call Heat Eco Building Services
Look, we're all for DIY when it's safe and sensible. Checking pressure, bleeding radiators, replacing thermostat batteries – go for it. But anything involving gas, electrical work, or taking the boiler apart? That's when you need a Gas Safe registered engineer.
We cover Farnham, Farnborough, Guildford, and the surrounding areas. Most emergency boiler repairs can be sorted same day, and we always explain what's wrong before we start work. No surprises, no jargon.
If your boiler is more than 10-15 years old and constantly breaking down, it might be time to think about boiler installation instead. Modern boilers are so much more efficient – you'll probably save enough on energy bills to offset the cost within a few years.
Keep Your Boiler Happy
The best way to avoid most of these problems? Annual servicing. It's like an MOT for your boiler – we catch small issues before they become expensive emergencies. Plus, it's usually a requirement to keep your warranty valid.
We're based right here in Surrey, we know the local properties, the water quality issues, and we've probably worked on your type of boiler a hundred times before. Give us a ring if your heating's acting up – we'll talk you through what might be wrong and book you in if needed.
Nobody wants to be without heating in February, that's for sure. But at least now you know what might be going on and whether it's something you can tackle yourself or if you need backup.
Stay warm, Farnham.
Having boiler trouble? Call Heat Eco Building Services on [your number] or visit Heat Eco to book your repair or service.