When the central heating goes on first thing in the morning by a timer it runs perfectly, however, after about an hour or so later the radiators get cold but the timer is still on. When I check the pump first thing it is very hot and vibrating and the spring loaded leaver below in the Honeywell silver box is forward as I have manually put it there but when the radiators go cold the pump is hot but not vibrating and sometimes the spring leaver is back on itself. Even if I manually put the spring loaded leaver forward again the water still does not go through to the radiators and the pump is still not vibrating but hot.
The radiators are not fitted with a TRV and they have been working ok for the past two years, when we moved in. i am moving the actuator by hand to allow the hot water from the pump to circulate to the radiators as sometimes the pump is hot and vibrating but the actuator of over and the pipe underneath is cold when I put it across the pipe and radiators get hot. Do you mean the pipes in the airing cupboard where the tank is? or the pipes to connected to the radiators as these are also cold. If I turn the speed control down the pump still vibrates but I have kept it on number 3. Could it be a problem with the timer itself as when I had the hot water on and the radiators off the radiators came on?