Dual fuel boiler

A fuel-fired heating appliance comprising:

• fuel burner apparatus having an inlet portion;
• pressure regulator apparatus having an outlet portion coupled to said inlet portion of said fuel burner apparatus, and a predetermined pressure regulation setting;
• and
• fuel delivery apparatus coupled to said pressure regulator apparatus inlet portion and operative to deliver thereto a selectively variable one of (1) a first fuel, from a source thereof, at a pressure greater than said predetermined pressure regulation setting, and (2) a second fuel at a pressure lower than said predetermined pressure regulation setting,
• said fuel burner apparatus being of a non-aspirating type, and
• said fuel-fired heating appliance further comprising a blower operative to supply combustion air to said fuel burner apparatus.

A fuel-fired heating appliance comprising:

• fuel burner apparatus having an inlet portion;
• pressure regulator apparatus having an outlet portion coupled to said inlet portion of said fuel burner apparatus, and a predetermined pressure regulation setting;
• and
• fuel delivery apparatus coupled to said pressure regulator apparatus inlet portion and operative to deliver thereto a selectively variable one of (1) a first fuel, from a source thereof, at a pressure greater than said predetermined pressure regulation setting, and (2) a second fuel at a pressure lower than said predetermined pressure regulation setting,
• said fuel burner apparatus comprising a plurality of fuel burners, and
• said pressure regulator apparatus comprising a plurality of pressure regulators operatively coupled to said plurality of fuel burners.

A fuel-fired heating appliance comprising:

• a fuel burner having an inlet orifice;
• and
• a fuel supply system for alternately supplying first and second fuels having different Wobbe indexes to said inlet orifice at different pressures related to said different Wobbe indexes in a predetermined manner such that the firing rate of said fuel burner remains substantially the same, without changing said inlet orifice, regardless of which one of said first and second fuels is being supplied to said fuel burner, said fuel supply system including:
• a first pressure regulator through which both of said first and second fuels must flow to reach said fuel burner, and
• a second pressure regulator through which only the higher Wobbe index fuel must flow to reach said fuel burner.

A fuel-fired heating appliance comprising:

• a fuel burner having an inlet orifice;
• and
• a fuel supply system for alternately supplying first and second fuels having different Wobbe indexes to said inlet orifice at different pressures related to said different Wobbe indexes in a predetermined manner such that the firing rate of said fuel burner remains substantially the same, without changing said inlet orifice, regardless of which one of said first and second fuels is being supplied to said fuel burner,
• said fuel burner being a non-aspirating type burner;
• and
• said fuel-fired heating appliance further comprising a blower operative to supply combustion air to said fuel burner.

A fuel-fired heating appliance comprising:

• non-aspirating type fuel burner apparatus having an orificed fuel inlet portion;
• blower apparatus for supplying combustion air to said fuel burner apparatus;
• a main fuel supply line structure coupled to said orificed fuel inlet portion;
• first pressure regulator apparatus connected in said main fuel line structure and having an inlet portion and a first pressure regulation setting;
• a first branch fuel supply line structure, coupled to said inlet portion of said first pressure regulator apparatus, for receiving a pressurized first fuel;
• a second branch fuel supply line structure, coupled to said inlet portion of said first pressure regulator apparatus, for receiving a pressurized second fuel having a Wobbe index higher than that of said first fuel;
• valve apparatus operable to permit flow of only a selectively variable one of said first and second fuels to said inlet portion of said first pressure regulator apparatus and thus to said orificed fuel inlet portion of said fuel burner apparatus;
• and
• second pressure regulator apparatus connected in said second branch fuel supply line structure and having a second pressure regulation setting,
• said first and second pressure regulation settings being related to one another in a predetermined manner such that, without altering said orificed fuel inlet portion of said burner apparatus, the firing rate of said burner apparatus will remain essentially constant regardless of which of said first and second fuels is being supplied thereto.

A dual fuel method of supplying fuel to burner apparatus having an inlet portion, said method comprising the steps of:

• providing pressure regulator apparatus having inlet and outlet portions and a predetermined pressure regulation setting;
• operatively coupling said pressure regulator apparatus outlet portion to the burner apparatus inlet portion;
• flowing to said pressure regulator apparatus inlet portion a selectively variable one of (1) a first fuel at a pressure greater than said predetermined pressure regulation setting, and (2) a second fuel at a pressure lower than said predetermined pressure regulation setting;
• and
• utilizing said pressure regulator apparatus to regulate the pressure of fuel discharged from its outlet portion only with respect to said first fuel.