My combi boiler started about a year ago intermitantly locking out on ignition,after resetting the boiler would then behave fine for a few days.This problem is now happening a couple of times a day and is becomming a real nuisance.I have had 2 people look at the boiler and neither of them managed to sort it out,the main problem being that it was an intermittant fault and sods law it always works ok when there watching it.The problem occurs on both central heating and hot water.The heating will work fine,firing up with no problems for four or five hours then it will suddenly lock out,the pump and fan will remain running but the burners will not light.From looking through the little window at the front i can see both ignitors sparking but the burner on the left is always the one which fails to ignite when i have witnessed it.Also recently when drawing hot water the water will only be slightly warm,the boiler will light but for whatever reason does not produce enough to heat the water,i can turn the tap on 10 or 12 times before the water will finally get back to normal temperature but throughout this it will not lock out.The boiler guy has offered to guess and change a few parts but said he can't guarantee it will work.So any pointers would be very gratefully received as this problem is getting me a seriously chewed ear of the missus 
thankyou.
thankyou.
