Abstract: A heater for liquid includes a vessel having an inlet for cold liquid and an outlet for hot liquid, an electrically operated valve means to control the flow of liquid into the vessel through the inlet, and an electric heating means to heat the liquid in the vessel. A first control means operative for controlling the liquid level in the vessel responds to a level sensor by maintaining the electrically operated valve means continuously open until the level of liquid in the vessel reaches an upper limit. The heater has a second control means operable independently from the first control means and which responds to a temperature sensor by rendering the heating means operative in response to a liquid temperature below a first threshold temperature being sensed, and inoperative in response to a liquid temperature above a second threshold temperature being sensed.

Abstract: There is provided a heater which includes a vessel in which liquid is contained, and a heater to heat the liquid, the vessel having an inlet by which liquid can be fed into the vessel, and an outlet through which liquid may flow to a point of delivery. The inlet comprises a supply conduit connected to a liquid supply, and liquid flowing along the supply conduit is mixed with a gas. A gas trap is provided to collect gas passing with the liquid from the supply conduit within the vessel, and includes an opening to release collected gas into the vessel, whereby at least when the liquid flow along the supply conduit is stemmed, the released gas provides an expansion space in the vessel into which liquid can expand during subsequent heating, the expansion space being vented from the vessel. An air control valve restricts the amount of gas available for mixing with the liquid as the liquid flow rate through the supply conduit increases, thereby preventing aeration of the liquid.

Abstract: A fluid flow control valve comprises a valve housing through which passes a deformable tube for receiving a flow of fluid, and means movable within the housing for constricting the tube, said constricting means comprising a valve plunger arranged for sliding movement within a valve housing in the form of a valve block under control of a control cam, and a plunger and valve housing respectively having shaped tube-contacting surfaces between which the tube is compressed by the sliding movement of the plunger.