Boiler Blows fuses!!!!

[Caesar]

Hi All

Same problem has occurred!!!! Even after PCB was replaced a few weeks back the Boiler is again blowing fuses!!!! The CORGI Engineer replaced the PCB which was black in colour with one which was Blue in colour!!! Does this make a difference and if not what else could be wrong!!!! Many thanks

 

[Agile]

Hello All

Had the CORGI Engineer in again and fixed the problem by replacing the PCB (Not that I know what it is or what it does)! Many thanks to everyone for thier kind input, learned a lot.[/quote

Thank YOU for reporting the outcome. learned as much as you, as have other readers.

I think you spoke too soon!

The answer is yet to be determined!

The different colour PCBs are of no consequence.

This is an intermittent fault and they can be difficult to find.

One way if you are stuck is to put a very low value fuse in series with the possible causes so that this blows first. Perhaps a 200 mA QB in series with the pump and a 100 mA QB in series with the gas valve.

Hopefully you will now be calling the repairer back to do the job properly?

Tony.

 

[Caesar]

HI Agile

Many thaks for your reply, engineer been told to come back sharpish!!!! Will keep you informed of the next set of events!!!

 

[jackthom]

but most boiler fans on dc so total different scenario

Yes but then there's the Back EMF to complicate the calculation.

You still can't just apply Ohms Law to a DC motor...... unless it's stalled of course.

 

[Caesar]

Hi All

Just had the engineer in and now he says its the programmer causing the Fuses in junction box which supply power to pump, boiler, programmer etc that is causing it!!! Is this correct or just try and see what module is at fault????

 

[Agile]

We dont know but it sounds most unlikely to me!

Usually pump and very occasionally the gas valve.

Tony

 

[twgas]

If the pilot lights, then - click - fuse blown is happening
I think the gas valve is number 1 suspect (main solenoid)

 

[kevplumb]

vaillant turbomax used to be a sod for them and they would take the board out aswell

 

[Caesar]

Hi TWGas

The boiler once the Main box whihc supplies electricity to the pump, programmer, boiler and 3 pin plug fuses have been replaced programmer lights come on. Then when Boiler is asked to start fans turns ok , clicking sound is heard to loght the pilot and then there a slightly louder click and then suddendly bang, programmer lights go out and fuses have to be replaced. I think pump is ok as body is vibrating when hand in placed on it!!

 

[twgas]

clicking sound is heard to loght the pilot

but does the pilot actually light?

 

[Agile]

Sounds to me like the second stage gas valve solenoid!

I would test that deduction by disconnection it and then seeing if the fuse blew when it was repowered.

Tony

 

[Caesar]

Hi All

The Pilot does not light as TWGas has asked but fuses blow when there is an audible click.

As for disconnection of the Main Solenoid Valve etc I am afraid I cannot touch the bioler as it has to be CORGI engineers. I think I am not even allowed to take the casing off!!!!

From the posts I gather that thr Programmer has nothing to do with this???

 

[bengasman]

Blind leading the blind as usual.

I appreciate that most of the people on here are not professional diagnostic engineers.

I also know that even if I tell you something then you will probably ignore what I am saying.
However, I will still say it although the term "pearls before the swine" comes to mind!

Its not always possible to identify a fuse blowing problem with a low voltage meter. Thats why an electrician has to use a 500v insulation tester.

Of course few people on here will even know much at all about electronics.

Suppose I ask you to email me with the answer to this simple question?

A gas boiler fan measures 44 ohms resistance. You connect it to 230v mains. What current is taken from the mains supply?

Tony

So after all this rambling trying to impress us all with your big headed knowledge you cant give him the answer because the answer is it cant be given unless you where there and worked on it.

So put all yea fancy big headed words back in there boxes and shut your big fat gob D..ck head.






And the answer to your question is 5.2 amps

I think not. A fan motor will draw a lot less as the the resistance will be added to the impedance.

 

[WDIK]

Hi All

The Pilot does not light as TWGas has asked but fuses blow when there is an audible click.

As for disconnection of the Main Solenoid Valve etc I am afraid I cannot touch the bioler as it has to be CORGI engineers. I think I am not even allowed to take the casing off!!!!

From the posts I gather that the Programmer has nothing to do with this???

totally correct, and for diagnosis, the fault is conclusively proven not to be the fan, as it runs, fault occuring at ignition, loud clicking so the spark is ok, fuse blows when gas valve attempts ot open.

if this is a real fault you need a real rgi, not the one who dianosed the clock, (need refund from him) to fix it.

 

[Caesar]

Hi All

Had the engineer around and he replaced the programmer and got the system runnning. Advised that system should be power flushed as sludge has built up. Many thanks to all for your very useful and informative replies.