Fan on continuously!!!!(vokera pro combi)

[jiminblack]

A faulty aps would not usually cause the fan to run with no external demand.
I'm not berating your boiler but it does say something about it after only 2 years service. Would need the operating sequence before trying to help with the fault. Guessing is not an option. I'd be looking at flow sensors and making sure all external controls are ok and not calling for the boiler fan to run.
Stew its not easy without being in front of the boiler.

I'm sorry, but the fan can carry on running if on some boilers the APS is stuck in the closed position.

 

[mickyg]

another fault you'll get with this boiler(although not in this case) is the venturi in the fan getting crud in and stopping the aps making. Expect that every 18months-2years.
you need someone to do some proper fault finding. I'd still say pcb without any demand but you need to confirm.

 

[45yearsagasman]

I'm sorry, but the fan can carry on running if on some boilers the APS is stuck in the closed position.

Jiminblack, Don't apologise, but I'm struggling to recall such a boiler. Perhaps you can give an example of that strange sequence of operation?
In all my years I've never changed an APS because the fan kept running.

 

[mickyg]

In all my years I've never changed an APS because the fan kept running.

ditto

 

[jiminblack]

Hands up poor diagnosis! Your right...I should stay away from forums when I'm ****ed! More likely venturi...but hey what do I know.

 

[Agile]

The venturi does nothing until the fan is started first by the PCB.

You must still be pi$$ed !

 

[Agile]

I dont know about this boiler but some use the fan to over run until the boiler has cooled down.

So in case this was the problem I would first do a simple test taking just one minute. Its quicker to do the test than find out if it has fan over run ( which is often not mentioned in the boiler manual anyway ).

With the boiler cold, measure the resistance of the two sensors. They should both be a very similar resistance and probably about 10k.

Tony

 

[DeltaT2]

The Pro combi can be Band A or Band B, but I can't find any MIs for them.
Though it does sound like the OP has a Band B - reading between the lines.