Dual-fuel heater

Abstract

According to one implementation a dual-fuel wall heater is provided that comprises a gas burner suitable for receiving a first gas or a second gas, a first pilot burner adapted to the first gas and a second pilot burner adapted to the second gas. The heater includes at least one pressure regulator, a control valve in fluid communication with the pressure regulator, and a selector valve in fluid communication with a gas outlet of the control valve. Each of the first and second pilot burners is arranged to direct a flame toward respective first and second thermocouples. The control valve includes an electromagnetic valve electrically connected to both the first and second thermocouples, the first and second thermocouples being arranged electrically connected in reverse polarity, such that in the event of the second gas being improperly supplied to the first pilot burner the resulting electromotive force generated by the first and second thermocouples is less than a disengagement threshold value of the electromagnetic valve.

What is claimed is: 
     
         1 . A dual-fuel heater comprising:
 a main gas burner configured to receive and burn a first gas or a second gas, the main gas burner comprising an injector through which the first or second gases are delivered to the main gas burner;   a first pilot burner assembly including a first pilot burner and a first thermocouple, the first pilot burner configured to receive and burn the first gas to produce a flame directed at the first thermocouple;   a second pilot burner assembly including a second pilot burner and a second thermocouple, the second pilot burner configured to receive and burn the second gas to produce a flame directed at the second thermocouple;   a pressure regulator that includes a gas inlet and a gas outlet, the pressure regulator being configured to regulate at the gas outlet a pressure of the first gas supplied at a first pressure to the gas inlet or to regulate at the gas outlet a pressure of the second gas supplied at a second pressure to the gas inlet;   a control valve having a gas inlet in fluid communication with the gas outlet of the pressure regulator, the control valve having a gas outlet, the control valve comprising an electromagnet valve, the first thermocouple electrically coupled to the electromagnet valve, the second thermocouple electrically coupled to the electromagnet valve, the electromagnetic valve having an engagement threshold voltage value at which the electromagnet valve transitions from a closed position to an open position and a disengagement threshold voltage value at which the electromagnetic valve transitions from an open position to a closed position;   a gas conduit in fluid communication with the gas outlet of the control valve, the second pilot burner being continuously in fluid communication with the gas conduit;   a selector valve having a gas inlet, a first gas outlet in fluid communication with the first pilot burner and a second gas outlet in fluid communication with the injector of the main gas burner, the gas inlet of the selector valve being in fluid communication with the gas conduit, the selector valve having a first position in which fluid communication of the gas inlet of the selector valve with the first pilot burner is enabled and in which fluid communication between the gas inlet of the selector valve with the main gas burner injector is enabled, the selector valve having a second position in which fluid communication of the gas inlet of the selector valve with the first pilot burner is prevented and in which fluid communication between the gas inlet of the selector valve with the injector of the main gas burner is enabled, there being fluid communication between the gas outlet of the pressure regulator and the second pilot burner when the selector valve is in both the first and second positions;   the first thermocouple and the second thermocouple being arranged electrically connected to one another in reverse polarity such that in the event of the second gas being supplied to the first pilot burner, a resulting voltage generated by the first thermocouple and the second thermocouple is equal to or less than the disengagement threshold voltage value.   
     
     
         2 . The dual-fuel heater according to  claim 1 , wherein the first gas is natural gas and the second gas is liquefied petroleum gas. 
     
     
         3 . The dual-fuel heater according to  claim 1 , wherein the first gas is natural gas and the second gas is butane gas. 
     
     
         4 . The dual-fuel heater according to  claim 1 , wherein the first thermocouple and the second thermocouple are connected to one another and with the electromagnetic valve in series. 
     
     
         5 . The dual-fuel heater according to  claim 1 , wherein the first thermocouple and the second thermocouple are connected to one another and with the electromagnetic valve in parallel. 
     
     
         6 . The dual-fuel heater according to  claim 1 , wherein the ratio of the engagement threshold voltage value to the disengagement threshold voltage value of the electromagnetic value is at least 4 to 1. 
     
     
         7 . The dual-fuel heater according to  claim 1 , wherein the first pilot burner and the first thermocouple function as a first oxygen depletion sensor and the second pilot burner and the second thermocouple function as a second oxygen depletion sensor. 
     
     
         8 . The dual-fuel heater according to  claim 7  wherein when the selector valve is in the first position to which the first gas is delivered to both the first and second pilot burners, the first thermocouple produces a voltage that is equal to or greater than the engagement threshold voltage value. 
     
     
         9 . The dual-fuel heater according to  claim 7 , wherein when the selector valve is in the second position and the second gas is delivered only to the second thermocouple, the second thermocouple produces a voltage that is equal to or greater than the engagement threshold voltage value. 
     
     
         10 . The dual-fuel heater according to  claim 1 , wherein the engagement threshold value is about 4 mV. 
     
     
         11 . The dual-fuel heater according to  claim 1 , wherein the disengagement threshold value is about 1 mV. 
     
     
         12 . A dual-fuel heater comprising:
 a main gas burner configured to receive and burn a first gas or a second gas, the main gas burner comprising a first injector through which the first gas is delivered to the main gas burner and a second injector through which the second gas is delivered to the main gas burner;   a first pilot burner assembly including a first pilot burner and a first thermocouple, the first pilot burner configured to receive and burn the first gas to produce a flame directed at the first thermocouple;   a second pilot burner assembly including a second pilot burner and a second thermocouple, the second pilot burner configured to receive and burn the second gas to produce a flame directed at the second thermocouple;   a pressure regulator that includes a gas inlet and a gas outlet, the pressure regulator being configured to regulate at the gas outlet a pressure of the first gas supplied at a first pressure to the gas inlet or to regulate at the gas outlet a pressure of the second gas supplied at a second pressure to the gas inlet;   a control valve having a gas inlet in fluid communication with the gas outlet of the pressure regulator, the control valve having a gas outlet, the control valve comprising an electromagnet valve, the first thermocouple electrically coupled to the electromagnet valve, the second thermocouple electrically coupled to the electromagnet valve, the electromagnetic valve having an engagement threshold voltage value at which the electromagnet valve transitions from a closed position to an open position and a disengagement threshold voltage value at which the electromagnetic valve transitions from an open position to a closed position;   a gas conduit in fluid communication with the gas outlet of the control valve, the second pilot burner being continuously in fluid communication with the gas conduit;   a selector valve having a gas inlet, a first gas outlet in fluid communication with the first pilot burner, a second gas outlet in fluid communication with the first injector of the main gas burner and a third gas outlet in fluid communication with the second injector of the main gas burner, the gas inlet of the selector valve being in fluid communication with the gas conduit, the selector valve having a first position in which fluid communication of the gas inlet of the selector valve with the first pilot burner and the first injector of the main burner is enabled and in which fluid communication between the gas inlet of the selector valve with the second injector of the main gas burner is prevented, the selector valve having a second position in which fluid communication of the gas inlet of the selector valve with the first pilot burner and the first injector of the main gas burner is prevented and in which fluid communication between the gas inlet of the selector valve with the second injector of the main gas burner is enabled, there being fluid communication between the gas outlet of the pressure regulator and the second pilot burner when the selector valve is in both the first and second positions;   the first thermocouple and the second thermocouple being arranged electrically connected to one another in reverse polarity such that in the event of the second gas being supplied to the first pilot burner, a resulting voltage generated by the first thermocouple and the second thermocouple is equal to or less than the disengagement threshold voltage value.   
     
     
         13 . The dual-fuel heater according to  claim 12 , wherein the first gas is natural gas and the second gas is liquefied petroleum gas. 
     
     
         14 . The dual-fuel heater according to  claim 12 , wherein the first gas is natural gas and the second gas is butane gas. 
     
     
         15 . The dual-fuel heater according to  claim 12 , wherein the first thermocouple and the second thermocouple are connected to one another and with the electromagnetic valve in series. 
     
     
         16 . The dual-fuel heater according to  claim 12 , wherein the first thermocouple and the second thermocouple are connected to one another and with the electromagnetic valve in parallel. 
     
     
         17 . The dual-fuel heater according to  claim 12 , wherein the ratio of the engagement threshold voltage value to the disengagement threshold voltage value of the electromagnetic value is at least 4 to 1. 
     
     
         18 . The dual-fuel heater according to  claim 12 , wherein the first pilot burner and the first thermocouple function as a first oxygen depletion sensor and the second pilot burner and the second thermocouple function as a second oxygen depletion sensor. 
     
     
         19 . The dual-fuel heater according to  claim 18 , wherein when the selector valve is in the first position to which the first gas is delivered to both the first and second pilot burners, the first thermocouple produces a voltage that is equal to or greater than the engagement threshold voltage value. 
     
     
         20 . The dual-fuel heater according to  claim 18 , wherein when the selector valve is in the second position and the second gas is delivered only to the second thermocouple, the second thermocouple produces a voltage that is equal to or greater than the engagement threshold voltage value. 
     
     
         21 . The dual-fuel heater according to  claim 12 , wherein the engagement threshold value is about 4 mV. 
     
     
         22 . The dual-fuel heater according to  claim 12 , wherein the disengagement threshold value is about 1 mV.