Modular tankless water heater control circuitry and method of operation

Control circuitry for a tankless water heater system, the tankless water heater system including a water heater module with four water conduits connected in series, the series connection being further connectable to a cold water supply and to provide a heated water flow to a heated water demand site, the control circuitry comprising:

• four water heater elements, one each associated with each of the plurality of water conduits;
• a controller including a central processing unit programmed with an operating program;
• a plurality of sensors positioned in the water flow and electrically coupled to the controller, at least one of the plurality of sensors providing an indication of the water temperature in an outlet of the series connection;
• connecting and operating circuitry coupling each of the plurality of water heater elements to the central processing unit;
• and
• the central processing unit being programmed to control the connecting and operating circuitry in accordance with indications from the plurality of sensors to individually activate a first water heater element to a first power level for a first heat required in response to a demand for heated water, and for heat required greater than the first heat required and less than a second heat required in response to a demand for heated water the central processing unit increases the power level of the first water heater element in predetermined increments up to a mid-power level less than a maximum power level of the first water heater element;
• the central processing unit being programmed to control the connecting and operating circuitry in accordance with indications from the plurality of sensors to individually activate a second water heater element of the four water heating elements to the first power level for the second heat required, and for heat required greater than the second heat required and less than a third heat required in response to a demand for heated water the central processing unit increases the power level of the second water heater element in predetermined increments up to a mid-power level less than a maximum power level of the second water heater element;
• the central processing unit being programmed to control the connecting and operating circuitry in accordance with indications from the plurality of sensors to individually activate a third water heater element of the four water heater elements to the first power level for the third heat required, and for heat required greater than the third heat required and less than a fourth heat required in response to a demand for heated water the central processing unit increases the power level of the third water heater element in predetermined increments up to a mid-power level less than a maximum power level of the third water heater element;
• and
• the central processing unit being programmed to control the connecting and operating circuitry in accordance with indications from the plurality of sensors to individually activate a fourth water heater element of the four water heater elements to the first power level for the fourth heat required, and for heat required greater than the fourth heat required and less than a fifth heat required in response to a demand for heated water the central processing unit increases the power level of the fourth water heater element in predetermined increments up to a mid-power level less than a maximum power level of the fourth water heater element.

A method of controlling a tankless water heater system that includes a plurality of water conduits connected in series, the series connection being further connected to a cold water supply and to provide a heated water flow to a heated water demand site, the method comprising the steps of:

• providing a plurality of water heater elements, one each associated with each of the plurality of water conduits;
• providing a controller including a central processing unit programmed with an operating program, and coupling each of the plurality of water heater elements to the central processing unit, the operating program including the sequential steps of activating a first of the plurality of water heater elements in predetermined steps to a mid-power level of the first water heater element less than a maximum power level of the first water heater element, activating a second of the plurality of water heater elements in predetermined steps to a mid-power level of the second water heater element less than a maximum power level of the second water heater element, and activating the first water heater element from the mid-power level of the first water heater element to the maximum power level of the first water heater element and then activating the second water heater element from the mid-power level of the second water heater element to the maximum power level of the second water heater element;
• positioning a plurality of sensors in the water flow and electrically coupling the sensors to the controller, using at least one of the plurality of sensors as an indication of the water temperature in an outlet of the series connection;
• using the central processing unit individually activating the plurality of water heater elements to a predetermined power level, in accordance with the sequential steps of the operating program, in response to a demand for heated water, and using the operating program of the central processing unit determining the number of the plurality of water heater elements to activate and the power level of the activation by the demand for heated water.