Central heating system not turning off/on with timer.

[Amanda2801]

[b]My central heating system won't turn on or off with the timer. The valve has been replaced, and the cylinder thermostat replaced. Heating/water only works when the main power switch is turned on/off manually.The timer switch is working but not communicating witht the heating system? Any ideas? :?:
Amanda [/b]

[htg engineer]

The timer switch is working ? do you mean you can turn heating on and off by the timer, but when set to timed it will not turn heating/water on or off ?

If yes then you need to replace timer.

[marrtin]

Have you checked if a frost stat is over-riding the timer?

[Amanda2801]

The timer displays all times etc, but heating/water does not go on and off with set times, it has to be manually switched on/off with main power switch. Thanks for reply
Amanda

[marrtin]

IF the boiler always fires when the timer is in the off position, then either the timer itself is faulty, or a frost stat is set too high (or it's doing what it's supposed to if the boiler is in an outhouse or garage etc).

[carol donegan]

my heating comes on outside of the times set. the boiler and frost stat is in the garage.i've had a new timer put on but i still have the same problem. why is this?