GB1487771A - Combined circulator and mixer for hot water heating systems - Google Patents

Abstract

1487771 Mixers KLEIN SCHANZLIN & BECKER AG 6 Dec 1974 [13 Dec 1973] 52932/74 Heading B1C [Also in Division Fl] A combined circulator and mixer for a heating system comprises an impeller 3 drawing water from a mixing chamber 8 within the pump and casing 1 and discharging it via a heating flow spigot 10; a boiler return spigot 9 below the mixing chamber; and horizontally extending spigots 11, 12 which may serve for heating return and boiler flow respectively. Members 6, 7 which are screwed into the casing 1 to provide a restrictor 5 and a non-return valve 4 respectively can be interchanged to enable the roles of the spigots 11, 12 to be interchanged. A Y-shaped wall 13 having upper links separating the mixing chamber 8 from the spigots 11, 12 and a lower limb 14 dividing the spigot 9 into two parts communicating with the spigots 11, 12 respectively has an air-filled insulating chamber 19. The speed of the driving motor 2 is controlled by a temperature sensor. If there is no heat demand, so that motor speed and pump delivery are low, the non-return valve 4 stays closed and the impeller 3 draws cooled water from the heating return via the restrictor 5 into the mixing chamber 8 and delivers it back to the heating system. Water from the heating return, being cooler than water in the boiler and therefore of a higher specific gravity, settles in U-shaped passage 17 and blocks the flow of hot water from the boiler circuit. If heat demand rises, producing an increase of impeller speed and therefore of heating circuit flow, the pressure drop produced by the restrictor 5 increases and the pressure in the mixing chamber 8 falls. When the latter pressure has fallen sufficient below the pressure in the boiler circuit, the non-return valve 4 opens to communicate the boiler circuit with the heating circuit, the mixing ratio of the hot and cooled water in the mixing chamber 8 being determined by the valve 4 and the restrictor 5. The presence of the limb 14 within the spigot 9 provides an injector effect whereby some of the water from the boiler flow passes to the boiler return. The fixed restrictor 5 may be replaced by an adjustable throttle valve, Fig. 3 (not shown). The four-way mixer can be converted into a three-way mixer by means of a plug 20 which closes the spigot 9 and abuts the limb 14 to prevent communication between the spigots 11 and 12. The boiler return line is in this case connected to the heating return line.