Gas-fired condensing mode furnace

In a hot air furnace including means for burning fluid fuel, exhaust passage means for carrying the products of combustion from the burner means to an exhaust flue, heat exchanger means in the exhaust passage means for extracting heat from the products of combustion therein, air passage means for carrying a flow of air over the heat exchanger means to be heated thereby, and air moving means for causing a flow of air through the air passage means, the improvement comprising:

• means communicating with said exhaust passage means for enclosing said burner means, said burner means firing into said exhaust passage means;
• a fresh air duct communicating with said enclosing means for admitting combustion air thereto;
• condenser means in said exhaust passage means for removing water from the products of combustion therein, said condenser means being exposed to said air passage means;
• and second air moving means in said exhaust passage means for causing fluid flow therein from said fresh air inlet duct through said enclosing means and said exhaust passage means to said exhaust flue.