Causes of a faulty boiler gas valve and how to fix it
Boilers can break down due to faults in any number of parts. This is the case when it comes to faulty boiler gas valves. When most modern boilers detect a gas valve fault, they’ll enter lock out and display an error code. As such, resolving a gas valve boiler fault is essential to restore heating to the home.
The early warning signs of a faulty gas valve usually come in the form of rattling or humming. While most boilers will make some noise, this should be noticeably louder. Read on for the possible causes of gas valve faults, how to fix them and where to get boiler spares.
What does a boiler gas valve do?
To understand how gas valves can become faulty, lets first go over its role within the boiler. A boiler gas valve controls the flow of fuel to the burner. It’s opened when hot water or heat is called upon. The pilot light then ignites the boiler to allow for continuous heating. Once the NTC thermistor senses it has reached the appropriate temperature, the gas valve is closed. The printed circuit board (PCB) is responsible for detecting when the boiler is ready to start heating, as well as when to stop the flow of gas fuel.
Gas valve faults occur what the supply of fuel is disrupted. This results in scenarios where the boiler flame is either too small, disrupted or lost. Faults that cause too much gas to be let in can be dangerous.
Causes of gas valve faults for boilers
Seized/stuck valveÂ
One of the most common fault causes, a boiler gas valve can be stuck either open or closed. In the former case, gas will be letting by even when hot water and central heating are turned off. This valve closure failure is called ‘letting by’. The latter prevents any fuel reaching the burner. Boiler gas valves are mechanical components which makes them susceptible to becoming worn and misshapen.
Incorrect valve adjustmentÂ
Boiler gas values typically get adjusted during check-ups. Sometimes this can lead to incorrectly adjusted valves or valves which become misadjusted on accident. Sometimes a gas valve will be pre-adjusted to a setting that doesn’t fit within the boiler it’s installed in. This leads to a boiler’s gas valve being unable to open and close properly.
Wiring or connectivity problemsÂ
Internal wiring in boilers dictates how different parts and components speak to each other. This is signals are vital to boiler operations following the correct process. For example, sporadic or unreliable signals mean the PCB isn’t aware of the status of the boiler gas valve. These problems can in turn be caused by wires being shaken loose.
PCB malfunctionÂ
The printed circuit board (PCB) is the part responsible for controlling boiler components when a command is received. It’s also responsible for detecting issues and executing an appropriate reaction i.e. error codes or lock out. As such, if a fault cause can’t be easily identified, it could be the PCB that’s the issue. If so, it can cause issues in other areas like boiler waste disposal or the gas valve.
Defective valveÂ
Lastly, the gas valve for boiler can simply fail due to old age or damage. Cracks and large scale malforming can result in a valve being unfixable. Electrical systems can also be extremely costly to repair when they experience faults. In either scenario, it is often better to get a replacement boiler gas valve. Have a look at the NBS range of boiler spares.
Ways to fix a faulty boiler gas valve
How to go about fixing a faulty boiler gas valve will depend on what is causing the fault. The solutions to these faults therefore start with having a professional engineer investigate the boiler and find the issue. For connection and PCB issues this will require the use of a multi-meter. Simple electrical fixes will be a case of reconnecting a dislodged wire. However, more severe faults due to connection or PCB malfunctions can cost a lot to repair.
In the event a stuck valve cannot be returned to functionality by freeing, resetting, and testing, it will need replacing. This is because it likely has got stuck or seized due to irreparable damage. Reconditioning kits are available for some boiler parts, however, they tend to be far more expensive than replacing a gas valve.
Be sure to check your boiler warranty, as this can cover the cost of replacing a gas valve.
Gas Valve Boiler Spares UK
If you need a gas valve boiler replacement, NBS has a substantial range to choose from. We offer brand new spare parts for both old and new boiler models. That way, our customers are never at a loose end when their home is unexpectedly left without heat or hot water.