Hi, am looking after a friends place and the hot water has stopped working, am trying to avoid having to get an expensive plumber out! It's an.old system with a cylinder and the water has been heating up twice a day. Since yesterday it's stopped! The pilot light kept going out yesterday so we managed it get it lit but after a few minutes it stops firing and the water stops heating. Now the pilot light is staying lit but the system is not firing at all when the water or heating is switched on. Does anyone have any ideas or advice as to what it might be? Electricity to the switches is all ok, we thought it might be the thermocouple but then the pilot light would be off so all out of ideas! The day before this happened my partner drained the central heating system as is doing some work in the house, refilled it and all was fine, so could that possibly be connected? All suggestions much appreciated, thank you!