Potterton suprima 40 blowing 3 amp fuse & rcd.

[mickshields]

My Potterton Suprima 40 is blowing the switch 3amp fuse and tripping the rcd ,it is doing so although the programmer HW & CH are in the off position.I removed the programmer from the backplate & replaced fuse and the red boiler light came on but when iput the programmer back on it blew the fuses again,i bought a new programmer but when i attached it the fuses tripped again.I then removed the motorised valve wires from the junction box but the fuses blew again i rewired the valve and then removed the cylinder stat wires from the junction box turned switch on and the boiler red light came on and the programmer light up ,i replaced the wires for the stat and the fuses blew again,i bought a new cylinder stat wired it in and it has blown the fuses again.
What could be the problem any help would be much appreciated.

 

[Billy Bob Bob]

pcb,pump,or fan has jammed but you would need a demand on for this,the suprima has a known pcb problem

 

[mickshields]

Thanks for your reply Mark, would the fan ,pcb ,pump blow the fuses even if i am not asking the boiler to do anything, ie programmer in the off position.

 

[WHPES]

Suprima electrics are of a notoriously poor standard.

 

[rob jefkins]

The Suprima has a major issue with PCB's. They have been upgraded of late to overcome the problems experienced before.
Would suggest that you have the older board in the potterton and once upgraded to the newer one should overcome the problem.
The reason I say this is because I had a very similar problem recently (must have done a dozen fuses).
Good luck mate

 

[Puddle]

Had plenty of faulty suprima pcb,s not many blowing fuses,if fuse being blow by boiler and not external items,pump,motorised valve ect,would point to fan or have had a few wires come loose from the flow switches and touch casing
Do not keep putting fuses in and blowing as you will do more damage,so even if not pcb,time you have replaced fuse 10 times and blow them,may well have to add pcb to list of parts required

 

[rob jefkins]

The good thing about a suprima is that it does'nt have too many components to check. Have you tried a multimeter against the components? Worth trying. Tell your readings to Baxi and they will more than likely point you in the right direction.

 

[Puddle]

My Potterton Suprima 40 is blowing the switch 3amp fuse and tripping the rcd ,it is doing so although the programmer HW & CH are in the off position.I removed the programmer from the backplate & replaced fuse and the red boiler light came on but when iput the programmer back on it blew the fuses again,i bought a new programmer but when i attached it the fuses tripped again.I then removed the motorised valve wires from the junction box but the fuses blew again i rewired the valve and then removed the cylinder stat wires from the junction box turned switch on and the boiler red light came on and the programmer light up ,i replaced the wires for the stat and the fuses blew again,i bought a new cylinder stat wired it in and it has blown the fuses again.
What could be the problem any help would be much appreciated.

This is a text book example of how not to test the wiring of a system,it shows very limited knowledge of electric's and system wiring,this is no disrespect to Mick but you are going to have to learn to use a multi meter,seems a little knowledge is a dangerous thing here,you could end up electricuting yourself or starting a fire and burning the house down
To do the above to system is not acceptable
Place this post on the sister electrical site and see the result
After reading through fault does not point to boiler anyway

If this was gas being messed with many here would be up in arms

 

[rob jefkins]

Yep, I agree Puddle. Only made this mistake once, then done a few courses on multi meters. No need for this really. Hence found fault on pcb and replaced. job done.

 

[LIFES A GAS]

The Suprima has a permanent Live feed to it so even with the programmer in off position there is still power to the boiler to control frost stat and pump over-run features. I would start by checking those first.
Martin

 

[Puddle]

The Suprima has a permanent Live feed to it so even with the programmer in off position there is still power to the boiler to control frost stat and pump over-run features. I would start by checking those first.
Martin

Yes but during the crazy testing process under taken,when he disconnects programmer or cable to cylinder thermostat,replaces fuse AGAIN and puts power on ,there is power to boiler/boiler light on and not fuse blows,indicating boiler ok,for how much longer though,who knows

 

[LIFES A GAS]

My Potterton Suprima 40 is blowing the switch 3amp fuse and tripping the rcd ,it is doing so although the programmer HW & CH are in the off position.

So it could be perm live or more likely HW off power is supplied from programmer to grey wire on 3 port which is also powered via cylinder thermostat when satified.

I removed the programmer from the backplate & replaced fuse and the red boiler light came on

We can rule out perm live at this point as red light on boiler, as programmer is not connected to it's baseplate there would be no feed to motorised valve from HW off.

but when I put the programmer back on it blew the fuses again,

feed from HW off to valve grey wire or cyl stat satified again.

I bought a new programmer but when i attached it the fuses tripped again.

As above

I then removed the motorised valve wires from the junction box but the fuses blew again

That rules out the motorised valve, so it's now looking like it could be the wire from programmer HW off and the junction box aor the cylinder stat satified wire as it shares the same terminal in the junction box.

i rewired the valve and then removed the cylinder stat wires from the junction box turned switch on and the boiler red light came on and the programmer light up

Rule out HW off to junction box then, now narrowing it down to the ware between junctiom box & cylinder stat satified.

i replaced the wires for the stat and the fuses blew again,i bought a new cylinder stat wired it in and it has blown the fuses again.

You say you replaced cyl stat wires not renewed?

iWhat could be the problem any help would be much appreciated.

Renew the cable between Cylinder stat & junction box or am I missing something?

Martin.