A sectional boiler for producing hot water, comprising:
- a front section that includes a heat exchanger portion having a hollow interior space configured and adapted to be filled with water;
- a back section that includes a heat exchanger portion having a hollow interior space configured and adapted to be filled with water;
- a second section that is arranged between said front section and said back section, and that includes an upper heat exchanger portion and a lower target wall portion which both have a hollow interior space configured and adapted to be filled with water;
- a third section that is arranged between said second section and said back section, and that includes a heat exchanger portion having a hollow interior space configured and adapted to be filled with water;
- a flue collector hood arranged above said respective heat exchanger portions of said front section, said second section, said third section and said back section to define and bound a flue collector chamber between said flue collector hood and said respective heat exchanger portions;
- and
- an upper draft diverter arranged in said flue collector chamber above said heat exchanger portion of said third section;
- wherein:
- said upper draft diverter divides said flue collector chamber into a flue gas diverting chamber on a front side of said draft diverter and a breech chamber on a back side of said draft diverter;
- said target wall portion of said second section forms a divider between a combustion chamber on a front side of said target wall portion and a heat exchange chamber on a back side of said target wall portion;
- at least one first flue passage communicates from said combustion chamber to said flue gas diverting chamber, between said heat exchanger portion of said front section and said heat exchanger portion of said second section;
- at least one second flue passage communicates from said flue gas diverting chamber to said heat exchange chamber, between said heat exchanger portion of said second section and said heat exchanger portion of said third section;
- at least one third flue passage communicates from said heat exchange chamber to said breech chamber, between said heat exchanger portion of said third section and said heat exchanger portion of said back section;
- said boiler has a flue outlet communicating out of said boiler from said breech chamber;
- said boiler is configured to allow a fuel to be introduced and burned in said combustion chamber, to produce combustion gas;
- and
- said target wall portion and said upper draft diverter are configured and arranged to cause at least a majority of the combustion gas to flow from said combustion chamber through said at least one first flue passage to said flue gas diverting chamber, and from said flue gas diverting chamber through said at least one second flue passage to said heat exchange chamber, and from said heat exchange chamber through said at least one third flue passage to said breech chamber.