Smart electric heater for bathing installations

A water heating system for a bathing installation, comprising:

• a resistive heating element disposed in a housing configured for placement in a water flow path of the bathing installation;
• a switching system configured to selectively connect the resistive heating element to main lines of an AC power connection providing a high voltage AC signal;
• a heater control system responsive to control signals received via a control interface to control the heating system to heat the water in the bathing installation to a selected water temperature, the control system including a microcontroller configured to control the switching system to control current flow to the heating element;
• and
• a monitoring circuit for monitoring the impedance of the heating element;
• wherein the microcontroller is responsive to the monitoring circuit to detect dry fire conditions in dependence on changes in the impedance of the heating element.

A water heating system for a bathing installation, comprising:

• a main resistive heating element disposed in a housing configured for placement in a water flow path of the bathing installation, and configured to heat the entire volume of water in the housing;
• a switching system configured to selectively connect the resistive heating element to main lines of an AC power connection;
• a heater control system responsive to control signals received via a control interface to control the heating system to heat the water in the bathing installation to a selected water temperature, the control system including a microcontroller configured to control the switching system to control current flow to the heating element;
• and
• a flow measuring system for monitoring water flow through the housing, the flow measuring system including one or more local heating elements for applying heat in a local heating zone within the housing under control of the microcontroller, a local temperature sensor for obtaining temperature readings within the local heating zone and a reference temperature sensor disposed upstream or downstream of the local heating zone within the housing, and wherein the microcontroller is responsive to sensor signals from the local and reference sensors to detect and measure water flow through the housing.

A water heating system for a bathing installation, comprising:

• a resistive heating element disposed in a housing configured for placement in a water flow path of the bathing installation;
• a switching system configured to selectively connect the resistive heating element to main lines of an AC power connection;
• a heater control system responsive to control signals received via a control interface to control the heating system to heat the water in the bathing installation to a selected water temperature, the control system including a microcontroller configured to control the switching system to control current flow to the heating element;
• and
• a liquid flow monitoring system for monitoring water presence and flow through the housing, the flow monitoring system including a thermistor disposed within a probe mounted in the housing, an excitation circuit to power the thermistor, wherein the microcomputer is configured to process a thermistor measurement signal to detect flow through the housing.