Biomass stove with warmed secondary combustion air

Abstract

A biomass furnace including a housing, a burn chamber configured to hold a biomass fuel, a fuel loading door to open and close a fuel loading opening, and a secondary air system that includes a main tube and a plurality of branch tubes oriented transverse to the main tube. The main tube includes a front opening, a main tube interior in gaseous communication with the front opening, and at least one aperture in gaseous communication with the front opening and configured to direct secondary air downwardly. Some or all of the branch tubes include at least one aperture in gaseous communication with the front opening of the main tube and which is configured to direct secondary air downwardly.

What is claimed is: 
     
         1 . A biomass furnace comprising:
 a housing comprising a front wall, a rear wall, a thickness extending from the front wall to the rear wall, a bottom, a top, a height extending from the bottom to the top and perpendicular to the thickness, and a width perpendicular to the thickness and the height,   wherein the front wall, the rear wall, the bottom and the top define an interior comprising a burn chamber configured to hold a biomass fuel undergoing combustion,   wherein the front wall comprises a fuel loading opening configured to load the biomass fuel into the burn chamber and a fuel loading door to open and close the fuel loading opening,   wherein the housing comprises an air inlet in gaseous communication with the burn chamber configured to feed air from an exterior environment into the housing interior,   wherein the biomass furnace is configured to warm air entering through the air inlet,   wherein the housing comprises an air outlet in gaseous communication with the burn chamber configured to feed air warmed by the biomass furnace from the housing interior to the exterior environment;   wherein the interior further comprises a secondary air system comprising a longitudinal main tube located above the burn chamber, the main tube comprising a front opening and a main tube interior in gaseous communication with the front opening, and a plurality of branch tubes attached to and oriented transverse to the main tube and each branch tube comprising a branch tube interior in gaseous communication with the front opening;   wherein the main tube further comprises at least one aperture in gaseous communication with the front opening and configured to direct secondary air downwardly; and   wherein at least one of the branch tubes comprise at least one aperture in gaseous communication with the front opening and configured to direct secondary air downwardly.   
     
     
         2 . The biomass furnace of  claim 1 , wherein the apertures of the branch tubes are configured to direct secondary air downwardly at an angle toward the front wall. 
     
     
         3 . The biomass furnace of  claim 1 , wherein:
 air from the exterior environment is entering through the air inlet;   the biomass fuel which is located below the main tube and the branch tubes and is undergoing combustion to warm the air entering through the air inlet and the burn chamber; and   the apertures of the branch tubes and the main tube are directing secondary air downwardly toward the biomass fuel undergoing combustion.   
     
     
         4 . The biomass furnace of  claim 1 , wherein the main tube is located approximately in the center of the housing width. 
     
     
         5 . The biomass furnace of  claim 1 , wherein the main tube comprises a main tube length extending generally parallel to the housing thickness. 
     
     
         6 . The biomass furnace of  claim 1 , wherein at least one of the branch tubes comprise a branch tube length extending generally parallel the housing width. 
     
     
         7 . The biomass furnace of  claim 1 , wherein the secondary air system further comprises a rear trunk chamber in gaseous communication with the front opening and comprising a plurality of apertures configured to direct air toward the front wall. 
     
     
         8 . The biomass furnace of  claim 1 , wherein the biomass fuel is configured to be located adjacent to the bottom of the burn chamber. 
     
     
         9 . The biomass furnace of  claim 1 , wherein the biomass furnace comprises a primary air system in the form of a forced draft system pushing air entering through the air inlet along a duct located adjacent to the fuel loading door and into the burn chamber. 
     
     
         10 . The biomass furnace of  claim 1 , wherein:
 one or more walls of the housing comprise a duct; and   the biomass furnace further comprises one or more distribution fans that may be located adjacent to the bottom and configured to blow air into the duct.   
     
     
         11 . The biomass furnace of  claim 1 , further comprising:
 a chimney connector located adjacent to the top;   one or more combustion fans adjacent to the chimney connector; and   wherein the one or more combustion fans are configured to intake warm air, blow the warm air through a duct located in the top of the interior of the biomass furnace, the duct configured to further preheat the warm air passing therethrough, and the duct configured to direct the warm air down the front and then into the secondary combustion system.   
     
     
         12 . The biomass furnace of  claim 1 , wherein the biomass furnace is configured to provide forced draft primary and secondary combustion. 
     
     
         13 . The biomass furnace of  claim 1 , wherein:
 the front wall comprises one or more barometric dampers; and   the biomass furnace further comprises one or more combustion fans to push the barometric dampers closed when the one or more combustion fans are running.   
     
     
         14 . The biomass furnace of  claim 13 , wherein natural draft is configured to pull the barometric dampers open as needed when the one or more combustion fans are not running. 
     
     
         15 . The biomass furnace of  claim 14 , wherein the one or more combustion fans are coupled to a thermostat. 
     
     
         16 . The biomass furnace of  claim 15 , wherein:
 when the thermostat is calling for heat, the one or more combustion fans run; and   when the thermostat is not calling for heat, the one or more combustion fans cycle off.   
     
     
         17 . The biomass furnace of  claim 15 , wherein the biomass furnace is configured to provide forced draft primary and secondary combustion, and further wherein the barometric dampers are configured feed the primary and secondary air systems with enough air to have clean combustion in a minimum duty cycle without the one or more combustion fans running. 
     
     
         18 . The biomass furnace of  claim 1 , further comprising:
 one or more barometric dampers configured to selectively allow air through the air inlet; and   a combustion fan connected to the housing, next to the air outlet, the combustion fan configured to selectively close the one or more barometric dampers, generating a forced draft for primary and secondary combustion.   
     
     
         19 . The biomass furnace of  claim 1 , wherein the secondary air system further comprises:
 a chamber located underneath and at a rear of the main tube;   the chamber being in gaseous communication with the front opening;   the chamber comprises a wall extending downwardly and transverse to the main tube; and   the wall comprises a plurality of apertures configured to direct air forwardly to accordingly interact with and forwardly direct the air exiting the at least one aperture of the main tube and the apertures of the branch tubes.   
     
     
         20 . A biomass furnace comprising:
 a housing;   a burn chamber configured to burn a biomass fuel therein;   a primary air passageway feeding into the burn chamber;   a secondary air passageway feeding into the burn chamber;   at least one barometric damper connected to the housing and configured to selectively allow air into the primary and secondary air passageways; and   a combustion fan connected to the housing and configured to intake and forcibly blow warm air into the primary air passageway and the secondary air passageway, generating a forced draft for primary and secondary combustion and selectively closing the at least one barometric damper.