Boiler Not Firing Up in Redruth - Common Causes and How to Fix Them

Published August 2026 | Boiler Repair

This guide walks you through the most common reasons a boiler stops firing up, and what you can check yourself before calling in a Gas Safe registered engineer. If you're a homeowner in Redruth or anywhere across Cornwall dealing with a cold radiator and a boiler that refuses to start, read on.

Before You Start - Safety First

Working near a gas boiler always carries risk. Before you touch anything, there are a few non-negotiable rules to follow.

First, never attempt to open the boiler casing, interfere with the gas supply pipework, or try to relight a pilot light manually on a modern sealed boiler. These tasks are legally restricted to Gas Safe registered engineers in the UK. If you smell gas at any point, stop immediately, open windows, leave the property, and call the National Gas Emergency Service on 0800 111 999. Do not use any electrical switches or light sources until you are well clear of the building.

The checks covered in this guide are all external and safe for any homeowner to carry out. None of them involve removing panels or accessing internal components.

What You Will Need

The good news is that diagnosing a boiler that won't fire up typically doesn't require any specialist tools. Here's what you might want to hand:

• A small flat-head screwdriver (for the pressure filling loop valve, if your model has one)
• Your boiler's instruction manual (usually available as a PDF from the manufacturer's website if you don't have a paper copy)
• A smartphone to run the Voltrade GoFIX diagnostic tool if you want guided fault-finding
• A notepad to record any fault codes displayed on the boiler

Time estimate: most of these checks take between 15 and 30 minutes in total. If none of them resolve the issue, you'll know fairly quickly that a professional visit is needed.

Step-by-Step Instructions

Step 1 - Check the Power Supply

It sounds obvious, but a surprising number of call-outs our engineers attend in Redruth turn out to be a tripped circuit breaker or a boiler that has simply been switched off at the fused spur. Check your consumer unit (fuse board) and confirm the boiler's dedicated circuit hasn't tripped. Also check the fused spur switch on the wall near the boiler - it should have a red or orange indicator light showing it's live.

If the boiler's display is completely blank and there's no power reaching it at all, reset the circuit breaker and try again. If it trips immediately, you have an electrical fault that needs a qualified electrician or Gas Safe engineer.

Step 2 - Check the Thermostat Settings

Your boiler won't fire if the thermostat isn't asking it to. Make sure your room thermostat or smart thermostat is set above the current room temperature. If you're using a programmable thermostat, check that the schedule is set correctly - it's common for clocks to drift or for programmes to get accidentally changed.

Also check the boiler's own temperature dial. If it's been turned right down (sometimes this happens when someone brushes past it), the boiler may run but produce little or no heat. Set the flow temperature to at least 60 degrees Celsius for heating.

Step 3 - Check the Boiler Pressure

Low system pressure is one of the most common reasons a modern combi boiler won't fire. The pressure gauge on the front of the boiler should sit between 1 and 1.5 bar when the system is cold. If it's reading below 0.8 bar, the boiler's built-in pressure sensor will often prevent it from igniting as a safety measure.

To repressurise, locate the filling loop - this is typically a small braided hose or a built-in valve underneath the boiler. Open the valve slowly until the pressure gauge rises to around 1.2 bar, then close it and attempt to restart the boiler. Common boiler brands like Worcester Bosch, Vaillant, and Ideal each have slightly different filling loop arrangements, so check your manual for the exact method.

Step 4 - Check for a Frozen Condensate Pipe

Cornwall winters are generally mild, but we do get cold snaps - and in Redruth especially, older properties with external condensate pipes can suffer from freezing during prolonged cold weather. The condensate pipe carries acidic wastewater from the boiler to a drain, and when it freezes, the boiler locks out as a safety precaution.

The pipe is usually a white plastic pipe, around 21 to 22mm in diameter, that exits through an external wall. If it's frozen, you'll typically see ice around the pipe end or the boiler will display a specific fault code (check your manual - on many Baxi and Worcester Bosch models it's an EA fault). To thaw it, pour warm (not boiling) water over the pipe, working from the boiler end towards the drain. Once thawed, reset the boiler.

Step 5 - Check the Gas Supply

If your boiler has power and adequate pressure but still won't light, the next thing to check is whether other gas appliances in the home are working. Try your gas hob if you have one. If that's also not igniting, the issue is with your gas supply rather than the boiler itself.

Contact your gas supplier if you suspect a supply interruption. In some parts of Cornwall, particularly in rural areas around Redruth, properties use LPG rather than mains gas - if that's the case, check your LPG tank level and call your supplier if it's running low.

Step 6 - Look for a Fault Code and Reset

Modern boilers display fault codes on a digital screen when something goes wrong. These codes vary by manufacturer - an F1 on an Ideal boiler means something different to an F1 on a Glow-worm. Write down the code and either look it up in your manual or use the Voltrade GoFIX diagnostic tool to get a plain-English explanation of what it means.

Many fault codes can be cleared by pressing the reset button (usually marked with a flame symbol or the word "reset"). Hold it for around 3 to 5 seconds. If the boiler fires up, runs for a few minutes, and then locks out again displaying the same code, that's a sign there's an underlying fault that needs a professional to diagnose.

Step 7 - Check the Flue Is Clear

The flue is the pipe that takes exhaust gases out of the building, typically through an external wall or roof. If it's blocked - by a bird's nest, debris, or ice in rare cases - the boiler will shut down on safety grounds.

Have a look at the visible end of the flue from outside. If you can see an obvious obstruction, you may be able to clear it safely from ground level. Do not attempt to reach or climb to access a flue at height. If the flue outlet is blocked and you can't clear it safely from the ground, call an engineer.

What to Do If This Does Not Fix It

If you've worked through all seven steps and the boiler still won't fire, you're likely dealing with a component-level fault that needs an engineer. The most common internal faults our engineers find when attending non-firing boilers include:

• Faulty ignition leads or electrodes - these are the components that create the spark to light the burner. They wear over time and can crack or corrode.
• A failed gas valve - if the valve isn't opening, no gas reaches the burner and the boiler can't light.
• A faulty printed circuit board (PCB) - this is the boiler's control unit. When it fails, the boiler may have power but won't respond correctly.
• A blocked or failed heat exchanger - more common in older boilers or those that haven't been serviced regularly.

At this stage, the next step is booking a diagnostic visit. Engineers in the Redruth area typically charge between 60 and 100 pounds for a call-out and diagnosis. Repair costs vary depending on the part - a new ignition electrode commonly costs between 80 and 150 pounds fitted, while a PCB replacement can run from 250 to 500 pounds or more depending on the boiler model.

When to Stop and Call a Professional

There are certain situations where you should stop and call a Gas Safe registered engineer immediately, without attempting any further checks yourself:

• You can smell gas at any point
• The boiler is making unusual banging, clicking, or hissing noises
• There is any sign of water leaking from the boiler
• The boiler is displaying a fault code relating to carbon monoxide, combustion, or a heat exchanger fault
• Your carbon monoxide alarm has activated
• You've reset the boiler more than twice and it keeps locking out

It is a legal requirement in the UK that all gas work - including boiler repairs - is carried out by a Gas Safe registered engineer. You can verify an engineer's registration on the Gas Safe Register website by entering their licence number. Never hire someone who can't provide a valid Gas Safe ID card. This applies equally whether you're in Redruth, Truro, or anywhere else in Cornwall.

If your boiler is over 10 to 12 years old and repair costs are looking significant, it may also be worth getting a quote for replacement. A new A-rated combi boiler, supplied and installed in a typical Cornwall home, typically costs between 1,800 and 3,200 pounds depending on the brand, output size, and complexity of the installation.

Questions About This Process

Why does my boiler keep firing up and then switching off after a few minutes?

This is commonly called "short cycling" and it usually points to one of a few causes: low water pressure that drops further once the pump runs, a faulty thermistor giving incorrect temperature readings to the PCB, or a partially blocked heat exchanger causing the boiler to overheat and trigger its limit thermostat. It can also happen if the boiler is oversized for the system. A Gas Safe engineer can diagnose which of these is the cause fairly quickly, typically within a single visit.

Can I use a universal boiler reset procedure if I've lost my manual?

Most modern boilers have a reset button on the front panel, usually marked with a flame or the word "reset", and holding it for 3 to 5 seconds will attempt a restart. However, the specific fault code and what it means varies between manufacturers - Worcester Bosch, Ideal, Vaillant, Baxi, and Glow-worm all use different code systems. You can usually find your boiler's manual as a PDF on the manufacturer's website by searching the model number printed on the boiler's data plate. The Voltrade GoFIX tool also covers common codes across major UK brands.

How much does a boiler repair typically cost in the Redruth area?

Call-out and diagnostic fees in Cornwall typically run between 60 and 100 pounds. From there, labour is usually charged at 50 to 80 pounds per hour. Common repair costs include: ignition electrode replacement at 80 to 150 pounds fitted, gas valve replacement at 200 to 400 pounds fitted, and PCB replacement at 250 to 500 pounds or more. Always ask for a written quote before work begins, and confirm the engineer is Gas Safe registered before they start any work.