Expansion and degassing device for connecting to a circut system, in particular the circuit system of a building heating installation

Abstract

An expansion and degassing container is in an expansion and degassing device for connecting to a circuit system for a circulating liquid. Because the amount of circulating liquid in the circuit system constantly changes during operation, liquid is withdrawn from the expansion and degassing container by way of a pressure holding pump, or supplied via a supply line, if needed. The supply line for supplying the refilling liquid is provided as a closed line, a system separator being arranged at the beginning region of the line and the end region thereof penetrating the container cover of the expansion and degassing container in a pressure-tight manner. The valve of the supply line is controlled according to the liquid level in the container. A pressure load cell, which additionally controls the valve according to the pressure, is present as a unit for decreasing an undesirable level of negative pressure.

1 . An expansion and degassing device for connecting to a circuit system, the circuit system comprising a loop, including a return line, in which a circulating liquid is pumped and undergoes pressure and volume changes, the expansion and degassing device comprising
 a closed expansion and degassing container having a container cover,   a pressure holding pump via which the container is connected to a first point in the loop,   an overflow valve via which the container is connected to a second point of the loop,   an air bleed and safety valve,   a unit for supplying refilling liquid as needed to maintain liquid in the container at predetermined levels,   a unit for decreasing negative pressure in the expansion and degassing container,   a closed supply line of the unit for supplying the refilling liquid, and   a system separator of the unit provided in a beginning region of the closed supply line,   wherein the closed supply line in an end region thereof penetrates the container cover of the expansion and degassing container in a pressure-tight manner,   wherein the system separator opens a delivery path when a critical pressure increase occurs in the closed supply line, with a pressure increase starting from the end region,   wherein the delivery path leads past the expansion and degassing device, and   wherein the unit further comprises a pressure load cell which actuates the unit so as to supply refilling liquid for the purpose of reducing the negative pressure to below a limit value.   
     
     
         2 . The expansion and degassing device according to  claim 1 , further comprising
 a circulation line to which the pressure holding pump and the overflow valve are connected,   the circulation line comprising a circulation line supply line and a circulation line return line, and wherein the supply line is connected to the first point and the return line is connected to the second point of the loop.   
     
     
         3 . The expansion and degassing device according to  claim 1 , further comprising
 a circulation line to which the pressure holding pump and the overflow valve are connected,   the circulation line comprising a circulation line supply line and a circulation line return line, and   the circulation line supply line and the circulation line return line being connected at a distance from each other to two points of the return line of the circuit system.   
     
     
         4 . An expansion and degassing device according to  claim 1 , wherein the system separator comprises a three-chamber system having controllable inlet pressure, middle pressure and back pressure zones, so that liquid flowing back into the closed supply line from the expansion and degassing container is completely discharged to a collection point. 
     
     
         5 . The expansion and degassing device according to  claim 4 , wherein the collection point is a spillover siphon. 
     
     
         6 . An expansion and degassing device according to  claim 1 , wherein liquid and gaseous layers thereabove in the expansion and degassing container immediately adjoin each other without separation. 
     
     
         7 . An expansion and degassing device according to  claim 1 , wherein
 the unit for decreasing negative pressure includes a solenoid valve through which the refilling liquid is supplied,   a lower level switch is situated in the container, which switch is actuated for emission of a signal upon liquid level in the container falling below a predetermined level, and   a pressure measurement signal from the pressure load cell as a control signal of the solenoid valve takes priority over a level measurement signal of the lower level switch as a control signal of the solenoid valve.   
     
     
         8 . The expansion and degassing device according to  claim 7 , further comprising electronic controls via which a signal of the pressure load cell acts on the solenoid valve. 
     
     
         9 . The expansion and degassing device according to  claim 7 , wherein a signal of the pressure load cell acts directly on the solenoid valve. 
     
     
         10 . The expansion and degassing device according to  claim 7 , wherein the signal of the pressure load cell is a 220 volt switch signal which matches a 220 volt signal of the solenoid valve. 
     
     
         11 . A circuit system of a building heating installation, in which circulating water is pumped in a loop and undergoes pressure and volume changes, combination with an expansion and degassing device according to  claim 1  which expansion and degassing device is connected to the circuit system of the building heating installation. 
     
     
         12 . A cooling circuit system, in which cooling liquid is pumped in a loop and undergoes pressure and volume changes, in combination with an expansion and degassing device according to  claim 1  which expansion and degassing device is connected to the cooling circuit system. 
     
     
         13 . The expansion and degassing device according to  claim 8 , wherein the signal of the pressure load cell is a 220 volt switch signal which matches a 220 volt signal of the solenoid valve.