Hi, my potterton netaheat 10-16 mk 2, which has never put a foot wrong in 16 years, has started to do something weird. There is hot water, the boiler ignites after using hot water as per, but when the heating starts up, after about 5 mins when the rads are hot, it stops. It does not respond to turning the thermostat up. I tried turning the boiler off and on again and the heating fired up, but cut off again after it got all the rads warm, any ideas/ thanks, Mark. If I don't get back til later it's cos I'm at work.