I am having problems with my central heating and having a go myself to fix it. The main parts are as per the subject a Honeywell ST699 timer and a V4073 Mid Position Valve. My partner and I have been living at the property for 11 months now and about a month ago we kept on getting caught out in the morning with no hot water. Everything was fine before and we could time the heating and the hot water separately. Now the water doesn't heat properly and the heating doest seem to respond to whats going on with the thermostat. We also noticed that the timer was not switching on and off and was sometimes not switching off when it should have. The hot water was also coming on when the heating was and vice versa (I think!). I got my multimeter out and checked that the correct voltages were being swtiched to the valve and it didnt looked like it was. From my memory the heating wire to the valve was going from 0-150V and the hot water was not doing anything. I thought this may be due to the timer not doing its job properly so got another one from ebay and fitted it thinking it would solve all the problems. Unfortunately it doesnt look like it has. I have just tested the heating with the thermostat turned right down and the radiators are red hot. I have also noticed that it sounds like the boiler and pump switch on as soon as I plug in the timer, is this right? One test I was going to do was to see if the valve was moving manually. With the old timer it looked like the mechanism on the valve was moving where as with the new one it doesnt. I hope I have provided enough information for someone to be able to help (and not bored you too much!!). I cant see that there is a wiring problem as it was working in the past, which is why I was pointed towards the timer. Now I have ruled it out (I think), I'm now thinking its the valve. Any help would be greatly appreciated. Si EDIT: I have just noticed the boiler and pump being active it due to the cylinder thermostat. If I turn it down then everything shuts down, as soon as you hear a click when turning it up (meaning its reached the current temp) then it all kicks off again. This is without the heating or hot water being switched on.