potterton surprima 80

[barker]

Hi their i am new to this forum, can anyone throw some idea on this problem: potterton surprima 80 approx 4/5 years old, fault not firing up fully, when it switch on only one row of jets seems to light and its low in flame hight as if the pressure of gas is low entering the gas valve,the gas is T off from my cooker and my cooker pressure is ok could it be a faulty gas valve ? i have check the control board for the dry joints all over they seem ok. ckecking out the valve meter it appear that their are two colis wire in series total resistance approx 4.1k( the first two pins starting from the bottom reads 2.8k the last two reads 1.3k, when firing the voltage across the total risistance approx =212dc ) ps i am electronic service engineer not a gas engineer i will leave the gas work to the expert .

I have phone potterton (because my wife keep nagging me)someone comming next week to sort it out

 

[MANDATE]

Hi Barker.
I think you on the right lines, I had a problem that turned out to be the gas valve (one of the two solenoids had gone).
I stripped down the old valve to get some understanding of its function.
There is no permanent pilot light on these boilers but it appeared to me it goes through two stages. A pilot light stage followed by full flash up stage.
The two solinoids opening two different paths for the gas.
As your solinoids seem to be OK I would think one of the valves is sticking. I cant see it being low gas pressure but I suppose a blockage in a gas jet is a possability within the gas valve.
My thoughts are that Potterton will change the gas valve(£170 at least)

 

[ChrisR]

Could be the pcb not giving out the right voltages, which could also be because the temp sensor is faulty. Latter is least likely.