How to check if a boiler PCB is working
The PCB is arguably the most important part of any boiler, as it is responsible for controlling key processes and implementing safety measures. It constantly monitors signals from the boiler’s environment and the various parts within the unit. As such, it can often be best to check whether the PCB is having issues before sourcing boiler replacement parts in other areas unnecessarily. This post is designed to give you an overview of what can go wrong with a boiler PCB and how to check whether it’s working as it should be.
Where to find the PCB in a boiler
The printed circuit board (PCB) can be found within the boiler casing, typically at the level of the boiler display if one is present. This part is responsible for controlling many other parts of the boiler, such as the gas valve, fan, and burner, which means it is positioned in a way so it can be easily connected. However, this does not mean it can be easily accessed and homeowners should not try and repair or replace a PCB themselves.
There isn’t one size that fits all when it comes to boiler PCBs. Every brand will have a range of PCB parts, each of which will be unique to a certain boiler model. As a result, even if you know you need Worcester replacement parts, you still need to do some research to find out which PCB is the one you need.
Signs that the boiler PCB isn’t working
As the boiler PCB is an internal electrical part, it can sometimes be difficult to identify when it is has a fault that is causing it not to work. Equally, this can also make it difficult to judge whether a fault in another boiler part is due to the PCB failing or if it’s because that part has itself developed a fault. In either case, it can be useful to check for the following signs to determine if the PCB in your boiler is experiencing an issue.
The smell of burning from any electrical appliance should be a cause for concern. In boilers, this is typically caused a leakage that brings part of the PCB into contact with water. The damage this can cause will most likely stop the boiler PCB from working as it should. Checking for leaks and their causes regularly can be an effective strategy for maintaining PCB health.
The PCB is also connected to the boiler display interface, meaning it is an issue with the screen, which can be an indication that the PCB isn’t working properly. It could be the case that this is being caused by a power supply issue, although this will have to be investigated separately.
If the boiler is displaying an error code for a memory fault, it is likely to be due to a PCB that has been misconfigured. Sometimes, the boiler manual will be able to provide a solution to this code and allow you to re-synchronise the boiler. If this isn’t possible however, you will need the assistance of a gas safe engineer.
The PCB is designed to coordinate seamless working between components within the boiler for efficient operations. Loose wiring can disrupt communications between the PCB and key boiler parts, leading to malfunctions. The best example is a fault in either the boiler gas valve or fan, both of which will result in the boiler shutting down as a safety precaution. This can be evidence that the PCB is not sending the right signals, causing the burner to receive inadequate amounts of fuel or harmful gases to build up in the boiler respectively.
When the boiler turns off before it has reached the inputted temperature, this is often due to disrupted communications between the boiler PCB and the thermistor. It could also be the case that the thermistor isn’t reading the water temperature correctly, or that the PCB can’t receive the signals properly.
Types of PCB testing
Any circuit board should undergo a series of tests to establish its functionality before it’s put on the market. Some of these tests might be replicated by a gas safe engineer to check if a boiler’s PCB is working properly. This may include:
- In-circuit testing.
- Burn-in testing.
- X-ray inspection.
- Flying probe testing.
- Automated optical inspection.
- Functional testing (can include solderability, contamination, ‘peel’, micro-sectioning, and time-domain reflectometer (TDR) testing.
What to do if your boiler PCB isn’t working
Firstly, do not attempt to remove the boiler casing and inspect the PCB yourself. This can be dangerous if you haven’t taken the necessary precautions. Instead, call a qualified gas safe engineer and explain the problem. They will then be able to safely assess your boiler PCB and decide if you need a replacement.
New boiler PCBs for major brands
At National Boiler Spares, we keep a stock of key boiler parts and spares for all the major heating brands. This includes the likes of Vaillant, Baxi and many more. We also make sure to stock technical electrical parts such as PCBs, as well as kits for engineers to repair and replace certain parts. Contact us to get quick access to the boiler parts you need, whether it’s to restore heat to your home or help else someone restore efficient heating to theirs.