Electronic calcification indicator for flow heaters heated by PTC resistors

US4292499A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Peter Kleinschmidt · Munich, DE
• Hans Meixner · Haar, DE
• Valentin Magori · Gernsheim, DE

Key dates

• Filing date: Jul 23, 1979
• Grant date: Sep 29, 1981
• Expiry date: Jul 23, 1999

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N25/18
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A system is disclosed for indicating when a flow heater used for vaporization of water and heated by PTC resistors as heating elements therein must be decalcified. Within the flow heater a PTC resistor element is located at a water entry and also at a water exit region. A main PTC heater element is also provided between the entry and exit elements. Separate power supply lines are run to the exit and entry heating elements and an electronic circuit is provided which determines when a difference in current flow in the exit heating element compared to the entry heating element exceeds a given value indicative of the need for decalcification. The circuit connects with an indicator which is triggered when decalcification is required.