I have a Vokera Unica HE boiler which keeps giving me a 34 fault reading, (Fan tacho signal fault) Fuse OK, how can I sort this out.
Thanks in anticipation
On some models there was a situation where water dripped onto the fan causing it to burn out. Since then, they've come up with a shield that protects the fan.
Not DIY I'm afraid. You do need a boiler guy to check it over. How old is the boiler. Their fans can be around the exceptionally silly price of £300. There may be the option of fitting a cheaper one from a different boiler, but it will depend on what the guy finds.
Of course it may not be the fan, perhaps a simple, cheap thermistor.
Although I have no details on this particular boiler – a common method of providing a cheap ‘tacho’ signal is to fix a disc to the end of the shaft with regular apertures around its circumference and place an optical sensor at the edge. If your fan is using such a method to provide a tacho signal, then it might be that the disc apertures and/or sensor have become blocked with dirt.
If fitted, closely inspect the disc apertures for blockages and carefully clean the optical sensor with a suitable cloth – wiping both sides straddling the disc face.
A good post from Hymie...... obviously knows much more about this than I do. These boiler's fans are speed controlled. They work at several different speeds depending on the mode the boiler is in at the time. The tachometer is vital to fan control.
His idea is certainly worth a try :o)
The Builder,the fault has come on again and water is dripping from around the back which as you say needs the shield on the fan motor.will get the vokera engineer out to fix.