Why do boilers have fans?
When a piece of equipment has a fan inside or as part of it, normally the role of that fan is to cool things down when the equipment becomes too hot. This is not the case in boilers though, the purpose of a boiler fan is to ensure any toxic fumes are blown safely up and out of the system. The fan is an essential part of a boiler and in this article, we will be exploring exactly what it does, why it is important, and some common faults that can go wrong with them.
What is the role of the fan on a boiler?
If you have ever noticed that your boiler has a fan you might be wondering exactly what its function is, or if you’re having problems with your boiler fan what can be done to fix it. The normal workings of a boiler involve burning different fuel types in the combustion chamber.
By doing this harmful gases are released and need somewhere to go. Gases typically leave the system through a flue which is a large white pipe that directs the fumes out of the boiler. The flue gives the gasses an exit, but it is unable to move them out itself. This is where the fan comes in and helps to blow the gases through the flue and make sure that they are safely released. In addition, the fan stops flue gases from settling on the heat exchanger’s intake pipe, which can cause corrosion on top of other serious problems.
Are there safety mechanisms in the boiler fan?
The boiler fan starts up before any other elements as it is a crucial safety feature and needs to be operating correctly for your boiler to work both effectively and safely. However, boilers are designed with safety mechanisms in place to ensure the boiler does not try and fire up with a faulty fan.
For example, the fan is required to be registered as functional by the printed circuit board (PCB). The PCB registers the fan using an air pressure switch, so if the fan is not registered as operational, the boiler won’t start, and it will show a fault code on the display panel.
If a fault is found the boiler system as a whole will lock to stop any chance of a fire or malfunction as well as to avoid any more damage to the unit. In the situation of being locked out of your boiler, you will need to get in touch with a Gas Safe engineer to come out and repair the issue.
Is it dangerous to have a faulty boiler fan?
If there is a problem with your fan and it is not identified by the PCB, then it can certainly be dangerous. There is the possibility of fire in your home or carbon monoxide poisoning, but if you have a carbon monoxide monitor in place you can easily prevent the latter. However, the fan starts before any other part of the boiler, so if that start fails, the boiler will shut down, lock, and show an error message. This means it is unlikely that there are any significant dangers related to faulty boiler fans.
Common fan fault causes and how to repair them
Low fan speed
If your fan speed is low, this can lead to problems like the pilot light going out briefly after being ignited or you can be fully locked out. The only way to resolve a low-speed fan is to contact a Gas Safe engineer to come out and fix it.
Blocked condensate pipes
Condensate pipe blockages can happen during winter due to freezing in cold conditions. The role of these pipes is to remove damaging vapours from the system, so if they become blocked, the air pressure will fluctuate and the boiler registers different fan faults.
Fixing this issue will involve thawing out the pipe because it will likely be blocked by frozen vapours. When it has thawed, it is advisable to insulate it. If you live in an area that is especially prone to cold weather, you might want to contact a professional and seek advice on the most suitable type of lagging to use.
Malfunctions in the air pressure switch
If there is a malfunction in the air pressure switch, the boiler won’t fire up as it can’t register that the fan is working properly. As long as the system doesn’t have any blockages and the only problem is the switch, it can easily be solved by replacing the switch.
Loose connections
Sometimes wires and connections can get looser over time due to the fan producing small vibrations. There is a possibility that you might get locked out of the boiler if there is a loose connection between the PCB and the fan as it won’t be able to register the working condition of the fan.
The solution to this is asking an engineer to look out for any potential loose connections or wires and request that they service the boiler at the same time. Therefore, they will be able to tighten loose connections and resolve any other smaller problems they come across.
Boiler leaks
As frustrating as it is, leaks are quite common developments in boilers. If they are not found promptly, boiler leaks can cause extensive damage to components including the fan, which will result in the boiler not working. If the cause of the fault is corrosion from a leak, an engineer will need to locate the leak, fix it, and replace any affected parts like the pump seal or heat exchanger, and it might be necessary to replace the fan too.
Faults with the circuit board
Despite it being very unlikely, if all other possible causes have been explored, it could be that the PCB is transmitting incorrect messages to different parts of the boiler like the fan. To resolve this, your engineer should analyse the PCB using a multi-metre, as it might be that there are a few loose connections. If it is found that the connections are secure, the unit will need to be replaced. However, this can be expensive, so be sure to do your research as it could be more worthwhile to replace the boiler.
Conclusion
The fan inside a boiler is an essential component that needs to be in working order for the system to function as a whole. If you’re having problems with your system and are looking for high quality, affordable boiler parts, National Boiler Spares can help.
We specialise in providing refurbished boiler spare parts to help people find the exact components they need for their specific system without the worry of how expensive it will be. Explore our wide range of parts to find the one that is right for your boiler.