Central heating system chemical dosing apparatus

摘要

The present invention provides apparatus for dosing a fluid/water-filled central heating system with treatment chemicals. The apparatus comprises a vessel 1, an inlet pipe or hose (6, fig.2) and an outlet pipe or hose (5, fig.2) for coupling to the system, so that fluid/water from the system flows into vessel and fluid from the vessel flows to flush chemicals from within the vessel out of the vessel and into the system. The vessel has a piston 4 within it and the vessel wall defines a cylinder 1a in which the piston moves under pressure of incoming fluid from a first position, at which the vessel contains fluid to be dispensed into the system, to a second position, corresponding to substantially complete emptying of the vessel. Preferably, the piston has a bypass passage through or around it that opens when the piston substantially reaches the second position so that fluid/water from the system flows past the piston when the piston is at the second position. The bypass passage may comprise a central passage 8 extending up through the piston, or one or more internal longitudinal grooves formed in the outlet end of the cylinder (see fig.7).