Why does my boiler fan need to be replaced?

It’s the air pressure switch that monitors air pressure in the boiler and determines if the boiler is safe to fire up, and to continue running. Assuming there’s no blockage or fault with your boiler fan, it’s likely the air pressure switch needs replacing. If all other options have been exhausted, the PCB could be to blame.

Why is the air pressure switch on my boiler not working?

Assuming there’s no blockage or fault with your boiler fan, it’s likely the air pressure switch needs replacing. If all other options have been exhausted, the PCB could be to blame. This gives and receives signals to parts in the boiler, including the fan. If the PCB isn’t working, it won’t receive the correct signals.

Why does my boiler turn off when I Turn on the heat?

You can check boiler pressure by looking at the pressure gauge on the boiler. If the pressure is too low then the boiler will turn off. The leading causes of low boiler pressure includes a leak somewhere around the heating system. Check all of the radiators, pipes and around your boiler for water.

Why does the fan turn on when the furnace is on?

This will cause the fan to automatically turn on when the furnace is heating and shut off once the call for heat stops. If your fan limit switch was already set to AUTO (not pressed in), then you most likely either have a problem with your thermostat wiring or the fan limit switch is bad.

When do you turn off the Furnace Fan?

So, when the switch is working correctly, your furnace fan should turn on several minutes after thermostat calls for heat and turn off several minutes after the heat cycle ends. But if the furnace fan runs continuously, regardless of whether the furnace is heating or not, your furnace fan limit switch is either:

What happens when the fan on a boiler stops working?

When it recognises this issue, it effectively tells the PCB that the fan isn’t working. And, just as a boiler won’t fire up without the fan working, if at any point the PCB receives the signal that the fan has stopped working during operation, it’s going to cut gas supply to the gas valve.

What happens if your boiler fires up every few minutes?

If the boiler fires up every few minutes it is using gas but not heating your home. This wastes fuel which will increase your heating bills and carbon emissions and could lead to a damaged heat exchanger.

How does the Furnace Fan limit switch work?

Your furnace fan limit switch is basically a control system that determines when the furnace blower assembly should turn on and off. The system uses a “temperature probe” to detect temperature changes inside the heat exchanger (see image below) and turns your blower on and off in response.