Central Heating Pumps
This is the time of year when people start turning the heating back on, and if the central heating pump has not been used, will invariably be stuck.
Systems of this is the boiler starting up and quickly switching off when the water boils - (usually the pump is moving the hot water out of the boiler and cooler back in).
Dont need to call the plumber straight away - on the front of the pump is a disc which can be removed, the rotor of the pump then can usually be freed by turning it with a screwdriver.
Take Care some water may come out......