| 摘要 |
<p>1,240,346. Automatic temperature control of gas-fired systems. JUNKERS & CO. G.m.b.H. 23 Aug., 1968 [23 Aug., 1967], No. 40329/68. Heading F4A. [Also in Division G3] A gas or oil-fired water heater for a heating system having a two-speed circulating pump selectively supplying through a three-way valve a central heating system and/or domestic water has a first thermistor R1 in the region of a domestic water storage heater 20, a second thermistor R2 in the region of a heat exchanger 11, and a third thermistor R3 in the region of the central heating system 16, each thermistor being connected in a separate bridge circuit controlling a Schmitt trigger circuit which operates switching means, e.g. relays to control the system. A pilot burner 29 heats a thermo-couple 36 energizing a solenoid 34 so that amanuallyoperated spring-loaded valve is retained in its opened position except on failure of a gas supply, or when a safety device, i.e. thermistor R2 controlling contact b is above a determined temperature. When the circulating pump is operated at. high speed a differential pressure valve 40 operates a main gas valve 38, and when a domestic water tap 46 is opened a pressure switch 48 operates valve 50, allowing additional gas to flow to burner 27. When tap 46 is opened the circulating pump is driven at high speed through a circuit, not shown, causing a gas valve 38 to be opened by differential pressure valve 40, whereby heated water is circulated through storage vessel 20, the temperature of which is regulated by thermistor R1. At the determined temperature the circulating pump and valve 38 are rendered inoperative. If central heating is required, a switch (167, Fig. 6, not shown) is closed, the three-way valve being moved to the appropriate position and pump 26 runs at a high speed hence valve 38 is opened. At a determined temperature measured by thermistor R3, burner 27 is rendered inoperative and the pump speed is reduced to a lower value. Premature switching off of the central heating system by hot water from the vessel 20 is prevented by components (115, 121, 122, Fig. 4, not shown). The arrangement is additionally controlled by an on/off space thermostat (169, Fig. 6, not shown). Circuits are described in a Specification for controlling the various operations.</p> |
