Suprima 30 slow to start, flashing orange Siemens PCB

[blushy]

I have a Potterton Suprima 30 with the newer Siemens board as the old board failed a few years ago but the boiler has developed a fault which is baffling me. The timer comes on as it should and the three port valve moves to the correct position but then the boiler does nothing and the LED flashes orange maybe for a minute or sometimes five minutes and then eventually the pump in the airing cupboard starts then the boiler fires as it should and all is good. The boiler has not actually failed I just don't understand why sometimes the boiler starts straight away and other times it can be five minutes.

I'm a telecoms engineer by trade and am okay with electrics/electronics and wondered is there anything else I could check. Does this sound like a board problem or something else. I know the old Suprima boards were terrible and I wondered if what I am experiencing is likely to be the board.

 

[45yearsagasman]

You will need to test that you are getting a signal to the switched live at the boiler immediately the valve moves to its operating position.

 

[blushy]

Hi Pete,

Yes the switched live is fine and I took the head off the three port valve to check the valve moves fine etc.

The manual says for flashing orange 'Ext call for heat, temperature control set to off'

The time for the pump to start and then boiler fan to spin up can be anything from almost instant to five minutes of flashing orange. My gut instinct is the board.

 

[Gasescape]

New pcb needed ...
Common fault with this pcb ....

 

[blushy]

Thanks for confirming.

 

[Agile]

But, with that kind of system, I don't see that an occasional delay of up to 5 min is going to be very important!

Tony

 

[blushy]

It's just more irritating than anything pressing the EXT button and then wishing the damn thing to start. It makes strange noises coming from the pcb at night like a component breaking down with a high pitched ticking.

 

[Gasescape]

I generally find with this fault it starts of quite random & gets progressively worse to the point that it no longer functions & just flashes Orange thinking the boiler stat has been turned down. I've got about 500 suprimas remaining on my patch & have replaced a good few boards with this fault...