Header box for a furnace, a furnace including the header box and a method of constructing a furnace

A furnace, comprising:

• a heat exchanger;
• a combustion air inducer configured to generate air flow through said heat exchanger;
• a pressure switch configured to monitor a combustion pressure through said heat exchanger;
• and
• a header box configured to be coupled between said heat exchanger and said combustion air inducer, said header box comprising:
• a fixed orifice configured to regulate said air flow;
• and
• a negative pressure channel including a negative channel supply port that communicates with an inlet of said combustion air inducer, a negative pressure port configured to connect to a negative input port of said pressure switch and bleed ports configured to reduce a pressure received through said negative channel supply port at said inlet to a targeted range at said negative pressure port.

A method of constructing a furnace, comprising:

• placing a heat exchanger in a housing;
• positioning a blower in said housing wherein said blower can move air across said heat exchanger;
• and
• connecting a header box to said heat exchanger, wherein said header box includes:
• a fixed orifice configured to regulate said air flow and
• a negative pressure channel including a negative channel supply port that communicates with an inlet of said combustion air inducer, a negative pressure port configured to connect to a negative input port of said pressure switch and bleed ports configured to reduce a pressure received through said negative channel supply port at said inlet to a targeted range at said negative pressure port.