Pump, Boiler, Switches seem OK, but no circulation?
Glow-Worm Space-Saver boiler in garage is working but switches off quite soon as the water isn't circulating in the domestic/central heating system. Turning up the boiler thermostat makes the water boil and bang but the outlet pipe from the boiler is hot only for a couple of feet.
The pump is upstairs in the airing cupboard. I can hear/feel that the pump is working and the shaft can be seen to be turning when the plug is removed. The pump gets a bit warm even though the pipes to and from it are cold.
The system is switched by a simple time switch - no programmer - and the diverter for central heating is a manually operated open/close valve. The pipes from boiler to airing cupboard are 22mm.
The water in the boiler feed tank in the attic is at the correct level and the outlet isn't blocked. The water has Sentinal X100 inhibitor in it.
Any suggestions as to the cause of the problem, please?