potterton suprima

[ambrosia]

Everytime someone posts a potterton suprima fault it turns out to be the PCB and this one could be the same, but I'll ask anyway, particually as it had a new PCB a year ago

A colleague attended the call out 1st, it was an unvented system and he found it had lost pressure so he topped it up and left. That night it broke down again

When I got there boiler was locked out flashing red, and this time didnt need topping up

I reset it and waited for it to lock out again, after 15 minutes it hadnt
Tried turning all the radiators off and the cylinder stat off, but left the programmer calling for heat and the boiler turned to max, wanted to see if that would make it lock out. It went into its yellow flashing mode and waited idle until i turned the rads back on when it fired up no problems

thought maybe it had a circulation problem so i checked the pump which was working, noted it had no bypass but this system was installed many years ago and it hasnt happened before so i dont think its that

All this time the boiler hasnt locked out

Left the boiler working, but as I havent fixed anything i'm expecting to have to go back as soon as it breaks again

Any thoughts on stuff i should check or what it could be because i'm out of ideas



By the way does this boiler have any pressure sensors, if the water needs topping up will it shut itself down like a combi
I've seen them on both vented and unvented systems so i'm guessing they dont

 

[diamondgas]

I've had these o/heat because the pump o/run failed to operate and latent heat tripped the boiler .... Also had ignition leads shorting internaly that'd light 9/10 but fail the once, also giving a weak spark ... Hope that helps

 

[hammers4spanner]

i got sent out to install a new pcb on one of these and when i was replacing the old one the tennant said that one i was taking out was about 3 months old at max !!!
Reckoned she has had several of them inlast couple years lol , must be cheap tat.

 

[ambrosia]

how do i test pump overrun, do i just turn the boiler to min setting so it stops firing and see if the pump continues to run and how do you fix that, is than a new pcb

just checked MI electrode needs 3 to 3mm gap to the burner face so i'll check that and the leads

thanks Diamond

 

[ambrosia]

i got sent out to install a new pcb on one of these and when i was replacing the old one the tennant said that one i was taking out was about 3 months old at max !!!
Reckoned she has had several of them inlast couple years lol , must be cheap tat.

I read (on this forum) that their pcb were so bad they were featured on watch dog

 

[zeebeedee]

I've had these o/heat because the pump o/run failed to operate and latent heat tripped the boiler .... Also had ignition leads shorting internaly that'd light 9/10 but fail the once, also giving a weak spark ... Hope that helps

Pump overrun! Think you may have solved an issue I have been battling with!

 

[surreygasman]

Is this an old standard efficiency suprima ? If so has it had a PCB upgrade kit ? Have you checked the impedance of the thermistor ? If an old type PCB, i.e. not the upgraded kit, have you looked at the 4 diodes in the centre of the board for burning and overheating. These are the most comon faults with this boiler. Ive fixed literally 100's of these over the past years since they were released in the mid 1990's. On eof the best boilers Potterton have ever made after the Profile / Prima range.

 

[diamondgas]

how do i test pump overrun, do i just turn the boiler to min setting so it stops firing and see if the pump continues to run and how do you fix that, is than a new pcb

just checked MI electrode needs 3 to 3mm gap to the burner face so i'll check that and the leads

thanks Diamond

Spot on regards testing the o/run get boiler to max temp then turn off demand heating and hot water ... It's controlled through the pcb .. If I remember right the pcb actually stopped the pump when it switched to overrun?

 

[Pancho]

I have a suprima 40 that is tripping the mains rcd after about 5 minutes of the HW demand being turned on, less time if the CH is turned on. Replaced the pcb which, has made no difference. Really stuck now. Any experience of this fault?

 

[surreygasman]

Not necessarily a boiler fault. Around 90% of breakdowns are in the peripherals and not the boiler. If its tripping then thats a dead short, so you need to be looking in anything with a motor, pump, fan in boiler, motorised valve actuators etc. Check central wiring box to ensure that there are no whiskers of one cable touching something else. This problem Im afraid is a process of eliimination until you find the root cause. Also check the programmer, and run the system with the clock removed and 3 and 4 linked direct to mains in. Sometimes it has been known for the fine internal switch contacts of time clock to break off and cause short. Without looking at it, this is my best advice.

Check the wiring in to boiler L N E SWL, ensure pump is correctly wired direct from boiler L N PL.

 

[Pancho]

Not necessarily a boiler fault. Around 90% of breakdowns are in the peripherals and not the boiler. If its tripping then thats a dead short, so you need to be looking in anything with a motor, pump, fan in boiler, motorised valve actuators etc. Check central wiring box to ensure that there are no whiskers of one cable touching something else. This problem Im afraid is a process of eliimination until you find the root cause. Also check the programmer, and run the system with the clock removed and 3 and 4 linked direct to mains in. Sometimes it has been known for the fine internal switch contacts of time clock to break off and cause short. Without looking at it, this is my best advice.

Check the wiring in to boiler L N E SWL, ensure pump is correctly wired direct from boiler L N PL.

Thanks for the reply!

I did some testing today, after reading an article concerning the gas valve and solenoid. It stated that some gv's coils have been known to overheat and cause the rcd to trip. I expect to see 240-250 vdc across the input (raw dc) but I'm only seeing between 198-206vdc. I tapped the coils then fired up the HW only, and surprisingly it remains on passed the normal 5 minute point where it usually trips the rcd. The coils get warm but not too hot to touch.
Knowing that the CH will likely trip it still, I kept an eye on the voltage and temp of the coil. As expected, at around 4 minutes it tripped the rcd. Can't say I noted too much voltage change but the coils became unbearable to touch.
Anyone else ever had this kind of issue with the gas valve??