Vokera 25he red light fault!!!

[Pooly89]

Hi guys,

I have a customer with a vokera compact 25he. I had a fault with the pcb and that has been changed but I now have a fault that when the appliance is in the "off" position it flashes once a red then yellow led one after another then flashes green, pump runs, fan runs, no ignition fan and pump stays on for a while, then locks out with a solid red.

all fault finding sheets seem to be pointing inconclusively at the pcb, could the NEW pcb be faulty or is there another explanation for this?


Kind Regards

Pooly

 

[GrahamM]

In my experience in the majority of cases solid red lockout is faulty NTC issue on these.
Check APS making when fan runs and NTC resistance in range.
The vokera MI's are usually quite good at putting you in right direction if follow them systematically.

 

[Pooly89]

thanks graham. I have heard a few people mention the ntc's but I'm still at a loss as to why it is running the fan and pump when the boiler power switch is in the "off" position?

APS is passing 24v when fan running so that's ok but we have no voltage at the ignition connection on the board. no signs of damage to sparker or lead and continuity of the lead and spark...

 

[SilentMike]

am sure I've had this before and it was OH stat dunno why its running when in the off postion.
but if i rember right it was doing the exact same thing. i rember nearly ruling it out because most boilers normaly spark when its the oh stat, but it was fine once i reset it

 

[Pooly89]

is there a reset button on the limit stat then?

 

[SilentMike]

yea, the stat is on the right hand side

 

[mfgs]

Check the primary thermistor and the fan venture. Also if its running when in the off position make sure you put the pcb in right, its easy to get the on off selector in at the wrong point on the potentiometer on the board, I have done this myself and it confused me haha.

 

[Pooly89]

right guys

thanks for all your efforts, it's turns out my local spares place gave me the wrong board(the one which has a separate ignition board, i thought they had but they did nothing about it when challenged, lazy day i guess) so I have since taken it back, changed for the right one, had to adjust on/off potentiometer and hey presto, burn baby burn! haha

 

[mfgs]

I have also been done by that in the past, there is a red board and a green board. I cant remember now which colour has the separate ignition board with it.

 

[Pooly89]

not just me then, thats good haha. green one which has a separate green ignition board. just for future reference

 

[GrahamM]

Did not think of that, even though had same issue myself many moons ago.
The original board had the ignition module built into it but the new replacements come with separate main board and ignition module separate.
Did not think you could get the like for like replacement still.