Control system for water heaters

An instantaneous gas water heater comprising:

• a water inlet connected to supply water to a heat exchanger;
• a gas supply control valve connected to a gas supply and a main burner in the water heater, said main burner being positioned to supply heat to said heat exchanger to heat the water;
• a gas flow rate control valve connected between the gas supply control valve and the main burner to control the rate of flow of fuel to the main burner;
• a pilot burner connected to the gas control valve and located adjacent the main burner to supply an ignition flame to the main burner;
• a flow detection switch connected to the gas control valve and positioned at a water inlet location to detect flow of water therein and, upon detection of water flow, to cause the gas control valve to supply gas to the main burner;
• a first cut-off switch connected between the gas control valve and the water flow detection switch and located in a position to detect the temperature of water in the area of said water inlet and to break the circuit if the detected temperature of the water in the water inlet exceeds a predetermined temperature, thereby causing the gas supply control valve to reduce the supply of gas to the main burner;
• a second cut-off switch connected to the gas control valve and located in a position to detect the temperature of water in a water outlet receiving water from the heat exchanger and being capable of breaking the circuit and causing the gas supply control valve to reduce the supply of gas to the main burner if the detected temperature of heated water in the hot water outlet exceeds a predetermined temperature;
• and
• sensing means positioned adjacent said heat exchanger and connected to detect the temperature of the heated water and to cause the gas flow rate control valve to regulate the rate of fuel supplied to the main burner.

A control system for an instantaneous water heater having a water inlet, a fuel burner to heat water in a heat exchanger entering through the inlet and a hot water outlet comprising:

• a first valve connected to the burner to control the rate of flow of fuel to the burner;
• a second valve connected to the first valve and a fuel supply to supply fuel to the burner;
• a water actuated flow switch connected to the water inlet to detect passage of water therethrough and actuate the second valve upon detection of water flow;
• a first cut off switch electrically connected between the second valve and the flow switch and being capable of detecting the temperature of water in the water inlet and causing the second valve to close if the sensed temperature of water in the water inlet exceeds a predetermined level;
• a second energy cut off switch electrically connected to the second valve and being capable of detecting the temperature of water in the hot water outlet and causing the second valve to close if the sensed temperature of the water in the hot water outlet exceeds a predetermined level;
• a pilot burner located adjacent the fuel burner to ignite fuel in the fuel burner upon activation of the valve switch;
• a thermopile electrically connected to the second valve and located adjacent the pilot burner to receive and convert at least a portion of heat energy generated by the pilot burner to electrical energy to supply power to the control system;
• and
• a temperature sensor connected to the first valve which senses the temperature of the heated water and causes the first valve to regulate the rate of fuel supplied to the main burner.