A filling device for a pressurised heating circuit

A filling device or loop for a heating system comprises a fluid passage 14b with an inlet port 14c for connecting to a fluid supply and an outlet port 14d for connecting to a heating system fluid circuit. A dead mans valve 14 between the inlet and outlet is biased to a normally closed position to shut off fluid flow between inlet and outlet and is operable manually to permit fluid flow from inlet to outlet. The device may include a pressure regulator (25, Fig. 3A). The valve may be a spool valve with a spring to bias the valve closed and a manual actuator or button 15 to open the valve. The device may include a piston valve with a spring to close a fluid passage between the piston valve seat and a poppet valve, or an offset rotary cam acting against the piston valve seat. The device may be left in place after being used to pressurize a boiler (1, Fig. 3A) from a mains water supply (3, Fig. 3A). A one-way check valve (22, Fig. 2B) may be provided to prevent backflow from the heating circuit ...