Over the last few days our central heating boiler has been acting very strangely indeed. Currently we are only using to heat the water up in the tank and have it on a timer to come on first thing in the morning and again in the late afternoon however, when we came to use the hot water on Tuesday evening it was only luke warm which suggested that the timed event in the late afternoon hadn't worked. We pressed the button to override the time but the boiler didn't fire up, the pump was working but the pilot light didn't come on. We tried the central heating and this worked (same control box, same boiler) Next day, the time event in the morning worked and so did the evening timer. Thursday came and the afternoon timer didn't work again and when we tried to override it the boiler wouldn't fire again, not even when activating the central heating which worked last time. Desperate for ideas, I cut the electric to the boiler, restored it and it still didn't work. Even more desperately, I waited for the washing machine to finish and tried to override it again and...........the boiler fired up This morning, the timer event didn't work again (luckily we left it on for an hour or so last night so we had hot water) so I tested manually firing it again and hey ho it fired up first time. I'm utterly confused as to what the problem could be, initially I thought it might be the thermostat in the boiler playing up, then I thought the pilot light was faulty, then, possibly the control box was faulty. Trouble is, at some point all of these things have worked so i'm struggling to think what it might be. I have an engineer coming tomorrow and I guess he will be as confused as me. Has anyone had anything like this happen?