Hi, Over the past few days we've noticed that we have no hot water any more. It isn't cold, but it certainly isn't hot...it's barely warm, tbh. To describe our 'system': We have a gas boiler in the kitchen that heats water for both central heating (which still works) and for the hot taps. It fires up on demand, but doesn't seem to have any kind of 'tank' on it. We have a big tank in the airing cupboard that has an immersion heater (not sure how/when that works, but I guess we would have to turn it on manually). In the kitchen we have a timer that is set to switch on the boiler for hot water between 06:30 and 08:30 (it also has a separate timer for the radiators). The way I imagine it working is that the gas boiler heats water and fills the tank in the airing cupboard. I imagine there's a thermostat in there somewhere to tell the boiler when to stop, but I can't see it. I guess there's a closed circuit between the boiler and the tank, that the boiler heats up. I'm not sure what happens if we use up all the hot water in the tank while the boiler is switched on, but perhaps there's a valve so the boiler takes fresh water from the mains, or perhaps it continues to try to heat the water in the tank in a circuit, with the tank being filled from the mains(?). Anyway, something's not working, and I don't understand the system well enough to figure out what might be wrong and how to fix it. It does kind of seem like it's just a thermostat problem, and if it is in the airing cupboard with the tank then it is possible it might have been knocked when clothes/etc are put in there. It might also be possible that some pump isn't working - ie if the water isn't being pumped through the boiler and tank. If there's no flow, then I'm sure the boiler wouldn't turn on for safety reasons. ...but I'm just guessing. Any ideas?