Vaillant turbomax plus 824e

[justqualified]

Was at one of these today, heating ok but no hot water, checked flow/filter and replaced dhw aquasensor but still doesn't fire up for dhw, went through fault finding flow chart which says check/replace hall stat before replacing pcb, can anyone help me with this before ordering a new pcb as dont know what it means by hall stat.( i removed room stat wires from pcb and linked out terminals 3 and 4 and it still didnt work but didnt think that would make any difference anyway) Thanks.

 

[Vaillantman1997]

Was at one of these today, heating ok but no hot water, checked flow/filter and replaced dhw aquasensor but still doesn't fire up for dhw, went through fault finding flow chart which says check/replace hall stat before replacing pcb, can anyone help me with this before ordering a new pcb as dont know what it means by hall stat.( i removed room stat wires from pcb and linked out terminals 3 and 4 and it still didnt work but didnt think that would make any difference anyway) Thanks.

 

[justqualified]

Yes I changed the whole unit which had the 3 wire sensor so pcb it is then, is there a way I could have checked this sensor when tap on/off as in resistance between wires, thanks for your help.

 

[Agile]

Not really as it gives a pulsed output so a scope would ideally be needed.

It might be possible to get an indication on an analogue meter which would average the pulses but a digital meter would not respond correctly as it has to digitise voltage samples.

Its rarely the PCB at fault!

Are you sure the boiler is piped the correct way round and the turbine is actually turning?

Tony

 

[ChrisR]

Have you got the sensor in the right place - it's really easy for it not to be.

 

[justqualified]

Tony - boiler has been working for years so im assuming its piped the right way, thanks for advice.

Chris - I replaced the whole aquasensor and it can only be fitted one way or can the 3 wire sensor be in the wrong position, thanks for advice.

Will see when I go back

 

[justqualified]

Spot on again Tony, unknown to me the house had a new bathroom fitted by another company and they must have piped it wrongly, didn't realise this when changing the aquasensor as someone was changing the kitchen tap at the same time so we had mains isloated, found out when removed turbine today with boiler isolated, still thought aquasensor would work either way, thanks for all your advice.

 

[Bunnyman]

Bit scary when u find out that way bet u got wet! If u come to one again an u wanna check it ,first turn on the warmstart then open hot tap an feel the pipes underneath, if the lhs gets hot u know ur ok!

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[justqualified]

Just a bit, will mind that in future, have learnt a bit about these boilers during this, thanks.

 

[Agile]

These questions are better asked in the CC.

Join if you have not. We can be freer with our replies.

Glad that I managed to give you the key to the solution!

With a bit of experience its one of the first things to check that no plumbing work has gone on recently which might have been done wrongly. I even ask that on the phone before going there!

You also actually helped me because I was not totally sure that it would not spin with the flow in the opposite direction!

Tony