Abstract: The gas boiler is intended for room heating and producing hot water and has a gas-heated primary heat exchanger which feeds two heating circuits lying in parallel. The heat exchange medium is circulated via a rotary pump driven by an electric motor, arranged on the cold side of the primary heat exchanger and has a control mechanism which is arranged on the pressure side and controlled by speed or direction of rotation. This control mechanism serves to actuate a switch mechanism connected to the pump housing, in that it connects in series one or other heating circuit to the primary heat exchanger. The switch mechanism is arranged on the hot side of the primary heat exchanger in the pipework to the heating circuits.

Abstract: A circulating pump unit comprising a pump and a motor for heating and service water installations, in which the motor is settable to at least two different speeds of rotation by means of a rotation speed switch. According to the invention the motor (1) couples automatically and independently of the operational speed (n) set on the rotation speed switch (3), after switching off or switching on of the unit by means of a start-up switch (5) overriding the rotation speed switch to the rotation speed (n3) with maximum start-up moment (M3) and starts at this rotation speed and after a pre-determined time switches over to the operational rotation speed set on the rotation speed switch. Thereby the circulating pump unit will give a reliable start of the pump also after a standstill for a long time.

Abstract: In a device having a gas separation chamber situated between an entry pipe for a gas-containing liquid and an exit pipe for de-gassed liquid wherein a twisting motion is supplied to the gas-containing liquid in the chamber so that gas in the centrifugal field of flow is forced toward the center of rotation which falls on the center line of the chamber and passed to an outlet opening while de-gassed liquid flows away to the exit pipe at the circumference of the chamber, the improvement comprises a stationary sieve tube arranged coaxially in the chamber wherein the upper opening of the sieve tube is directed towards the outlet opening for the gas and connects the sieve chamber in primary connection with the exit pipe, which has a common center line with the entry pipe. The sieve piercings form a secondary connection to the exit pipe. The sieve tube is preferably installed at an angle of 45.degree. to the field of gravity of the earth.