Ravenheat Air Pressure switch

[jaymi]

Firstly thanks for reading this.

RAVENHEAT LS 100 T

So yesterday the flame failure light came on and the boiler having run pretty well for about 7 years decided to stop working...

From the following investigation the problem seems related to the fan/air pressure switch but am unsure how to proceed.

The CH pump runs no problem.

The fan is running, I have nothing to base it on from a relative point of view but seems to be chucking out a fair bit of air.

This lead to the air pressure switch. There are a couple of tubes connected to this. One is connected to nothing and finishes in mid air and the other is connected to the flue...flue to air pressure switch.

On removing one end of the connected (red) tube (I removed the end connected to the flue) and blowing very gently you can hear the switch trigger.

So with everything in order the only thing required to make the boiler light is to blow very gently through the tube connected to the air pressure switch.

This leaves me in a quandary. The air pressure switch definitely triggers if you blow through it. The fan is also running well (however I have nothing to base this on but does seem to be kicking out a lot of air).

It seems the tubes to the air pressure switch are not blocked.

So to recap:

Blowing gently through the air pressure switch via the hose connected to the air pressure switch causes the sparks, gas and the whole boiler to behave as normal.

Otherwise the fan and pump run but the air pressure switch never "clicks" and the boiler does not start.

Any ideas?

Thanks very much,
Jamie

 

[muggles]

You've managed to get a Ravenheap to keep working for 7 years!? That must be a record...

As for the problem, I have an idea but as it's gas-related I can't tell you what it is. You've already played around more than you should have, call a Gas Safe Registered engineer in

 

[jaymi]

Thanks for your help.

I see a fan costs about £150 and the switch about £30. I could get both but would rather avoid that if there was someway of determining if it is the fan or the air pressure switch. As the air pressure switch only seems to take a very small blow to trigger I am thinking it is the fan.

I noticed that after the air pressure switch has triggered (via manual blowing) you can no longer blow through it until it has disengaged. Is this normal?

Please can anyone tell me if the switch is triggered by air being drawn into the boiler as opposed to being blown out?

It would also be very helpful if anyone knew if there was a way to diagnose which part it was out of the fan or the switch.

I have checked the flu and there does not seem to be any blockage at all but will take the cap off later to have a good look inside.

 

[Agile]

You do not seem to have understood what Muggles has said above.

Common sense and the Forum rules mean that we do not give DIY advice on gas/combustion related problems.

In fact a DIYer should not even open the combustion chamber.

Any competent gas registered engineer will be able to diagnose the problem.

Tony Glazier