Vaillant Ecomax 824/2 E problem

[John The Rad]

Anyone worked on these boilers (My first)
The faulty Exp/vessel has caused the O rings on the heat exchanger to pop.I have replaced them all including the exp/vessel, but the left hand 10ma fuse on the PCB keeps blowing (The pcb was bone dry no water had got onto it)
I'm sick of buying fuses and disconnecting the fan then the pump etc.
PS is there a resettable device available to avoid having to keep replacing the glass fuse.
Anyone ever had this problem.

 

[dougal]

i would check polarity at boiler and resistance checks across pump, fan and gas valve

 

[John The Rad]

What I can't understand is that the fuse blows before anything attempts to start. The very second that the spur box is turned on the fuse blows.
The polarity can't be wrong. it's been running for six years before the problem.
When I first replaced the O rings the boiler started and was going for a week before I was recalled. It was then that I sussed that the Pressure vessel was not doing it's job.
I have advised a replacement boiler but they want me to try and fix this one first. (Waste of money if you ask me).
If I could sort what keeps blowing the fuse then I will have another satisfied customer. The question is what happened during that week after I had got it running?

 

[Nostrum]

you must have a short somewhere, what happened when you disconnected the pump and fan?

 

[John The Rad]

The fuse still popped

 

[Nostrum]

Have you disconnected every connector on the board or component it feeds ?

 

[John The Rad]

Not yet, I stopped working on it when the customer said he was thinking of replacing the boiler but rang later and asked me to have another go.
I have been too busy to go back yet but promised to return after the bank holiday. I will have to do what you mentioned above and disconnect everything from the PCB and re-fit them one by one until the fuse pops. Then I might be able to trace the fault. But it's a pain in the bott.
It might be the PCB itself. If it is then I think that might persuade him to go for a new one.

 

[Nostrum]

Also remove all external controls to eliminate them, can't really be much else.

 

[John The Rad]

Thanks for your input Sambotc

 

[southcoastboile]

You've probably done this already but check all connections for any water dammage, had the same thing on a boiler the other day tripping main rcd. No leaks anywere but previous leak had left a load of scale on the casing were the earth leads connect, cleaned up all the connections and it was fine.

 

[John The Rad]

Thanks mate, I will do that.

 

[DMC]

Had the same issue a while ago turned out to be the programer was at fault