Worcester 28Si Mark II - Intermitantly starting

Part way last night my boiler stopped working. The fault light came on Flashing 5 times a second, so I tried a reset Normally when it starts you hear the fans spin this time I got a slight turn, no signs of ignition after 20 seconds the same fault goes on.

I goto bed get up at 11am, i then worked fine until 3pm today. The same problem again, if I left it 30 mins I could get maybe a sink full of hot water, then the same problem, it sounds like a component is heating up and failing needing cool off time.

Midnight tonight I made a desperate attempt to get some hot water. I noticed that the presssure BAR was only about 1.3 which is rather low, its been this low before and it has been noisey. I increaed this to 1.8 - Hey presto the boilder worked, and now rads are even hot.


My question is, I booked the CH guys to come out and look at it on monday, could someone in the field or with expierence tell me what it might be, so far they suggested it might be Gas Value, or PCB problem. I belive it could be water flow, or gas supply also but I am no expert in this field. It seems weired that after it is left for some time it will work ok for a spell. I will see what it does tonight.

Thank you to anyone who can provide some insight
David.

if it helps it just went again, tried another reset it turned for half a second then ignition light came on and off about a dozen times, heard clicking like it was trying to ignite. - It will not start again. Oh well - is there anything you can suggest, i m concerened I`ll be ripped off as they may not be sure what the fault is its so intermitant.

Please help..........