Warm air furnace with managed combustion air flow

Abstract

A warm air solid fuel furnace is disclosed that includes a firebox defined by a floor, opposing sides, a top baffle, a front door, and a rear wall, wherein the firebox floor is at least partially lined with fire resistant material. A primary combustion air flow path includes one or more holes through the front door. A secondary air flow path receives air from a front of the furnace and conducts received air along a first opposing side of the firebox, up the rear wall of the firebox, and into at least one tube having orifices, the tube located beneath the top baffle. A rear pilot air flow path receives air from the front of the furnace and conducts received air along a second opposing side of the firebox, up the rear wall of the firebox, and into at least one hole through the rear wall.

What is claimed is: 
     
         1 . A warm air solid fuel furnace comprising:
 a firebox configured to receive wood, said firebox defined by a floor, first and second opposing sides, a top baffle, a front door, and a rear wall, wherein the firebox floor is at least partially lined with fire resistant material;   a primary combustion air flow path, wherein the primary air combustion flow path is one or more holes through the front door;   a secondary air flow path configured to receive air from a front of the furnace and conduct the received air along the first opposing side of the firebox, up the rear wall of the firebox, and into at least one tube having orifices, wherein the at least one tube is located at a top of the firebox beneath the top baffle; and   a rear pilot air flow path configured to receive air from the front of the furnace and conduct the received air along the second opposing side of the firebox, up the rear wall of the firebox, and into at least one hole through the rear wall of the firebox.   
     
     
         2 . The furnace of  claim 1 , wherein:
 the firebox floor comprises a section that is a grate that is not lined with fire resistant material; and   the furnace further comprises an ash tray mounted in the furnace below the grate.   
     
     
         3 . The furnace of  claim 1 , wherein a first inlet through the front of the furnace to the secondary air flow path is separate from a second inlet through the front of the furnace to the rear pilot air flow path, and secondary air entering the first inlet does not mix with rear pilot air entering the second inlet until the rear pilot air and the secondary air enter the firebox. 
     
     
         4 . The furnace of  claim 1 , wherein:
 the rear wall includes a rear wall baffle in communication with the rear pilot air flow path;   the at least one hole in the rear wall is defined through the rear wall baffle; and   the rear wall baffle comprises a plurality of holes therethrough, the plurality of holes providing increasing flow capacity lower on the rear wall baffle than higher on the rear wall baffle.   
     
     
         5 . The furnace of  claim 1 , wherein:
 the rear wall includes a rear wall baffle in communication with the rear pilot air flow path, the at least one hole in the rear wall defined through the rear wall baffle; and   a top of the rear wall baffle is closer to the front of the furnace than a bottom of the rear wall baffle such that the at least one hole is oriented to direct rear pilot air toward the floor of the firebox and toward the front of the furnace.   
     
     
         6 . The furnace of  claim 1 , wherein the fire resistant material is fire brick. 
     
     
         7 . The furnace of  claim 1 , wherein a top of the top baffle is lined with fire brick. 
     
     
         8 . The furnace of  claim 1 , wherein the top baffle is higher at the front of the furnace than at a rear of the furnace when the furnace is in an upright position. 
     
     
         9 . The furnace of  claim 1 , wherein:
 the top baffle is higher at a front of the furnace than at a rear of the furnace when the furnace is in an upright position;   the at least one tube is a series of tubes each having orifices;   the orifices in the series of tubes are oriented to direct secondary air from the secondary air flow path into the firebox toward at least one of the floor of the firebox and the front of the furnace; and   each tube of the series of tubes is spaced equidistant from the baffle.   
     
     
         10 . The furnace of  claim 1 , wherein the at least one hole in the rear wall of the firebox is located no more than half way up the rear wall. 
     
     
         11 . The furnace of  claim 1 , wherein the firebox is configured to preheat secondary air and rear pilot air as the secondary air and rear pilot air move from the front of the furnace to a rear of the furnace along the secondary air flow path and the rear pilot air flow path respectively. 
     
     
         12 . The furnace of  claim 1 , further comprising:
 an air plenum positioned above the top baffle; and   a gap between the top baffle and a front of the furnace, the gap allowing exhaust gases to pass from the firebox and into the air plenum.   
     
     
         13 . The furnace of  claim 12 , further comprising a flue in communication with the air plenum, said flue configured to receive exhaust gases. 
     
     
         14 . A warm air solid fuel furnace comprising:
 a firebox configured to receive wood, said firebox defined by a floor, first and second opposing sides, a top baffle, a front door, and a rear wall, wherein a rear portion of the firebox floor is lined with fire brick;   a primary combustion air flow path, wherein the primary air combustion flow path is defined by one or more holes through the front door;   a secondary air flow path configured to receive air from a front of the furnace and conduct air along the first opposing side of the firebox, up the rear wall of the firebox, and into a series of tubes having orifices, wherein the tubes are located at a top of the firebox and span laterally across the top baffle, and the orifices are oriented at least partially towards the firebox floor; and   a rear pilot air flow path configured to receive air from the front of the furnace and conduct air along the second opposing side of the firebox, up the rear wall of the firebox, and into a plurality of holes defined through the rear wall of the firebox.   
     
     
         15 . The furnace of  claim 14 , wherein:
 each of the tubes in the series of tubes has a first and second end; and   secondary air from the secondary air flow path is directed into both ends of the series of tubes.   
     
     
         16 . The furnace of  claim 14 , wherein the secondary air flow path and the rear pilot air flow path are separate and independent from one another within the furnace until the respective air flow paths reach the firebox such that a flow capacity of the primary air path, a flow capacity of the secondary air path, and a flow capacity of the rear pilot air flow path are independently predetermined to maximize combustion of the wood and combustible gases given off by the wood during combustion. 
     
     
         17 . The furnace of  claim 14 , further comprising:
 an inner housing, wherein the firebox, the secondary air flow path, and the rear pilot air path are positioned within the inner housing;   an outer housing at least partially enclosing the inner housing, a forced air passage formed between the inner housing and the outer housing;   an exit duct defined on the outer housing, the exit duct in fluid communication with the forced air passage; and   a blower unit mounted to the outer housing, the blower unit configured to force air through the forced air passage and out of the exit duct.   
     
     
         18 . The furnace of  claim 17 , wherein the firebox is configured to transmit heat to the air forced through the forced air passage by the blower unit. 
     
     
         19 . A warm air solid fuel furnace comprising:
 a firebox configured to receive wood, said firebox defined by a floor, first and second opposing sides, a top baffle, a front door, and a rear wall, wherein a portion of the firebox floor is lined with fire brick;   a primary combustion air flow path defined by one or more holes through the front door;   a secondary air manifold configured to receive air from a front of the furnace and conduct air along a first opposing sides of the firebox, up the rear wall of the firebox, and into a series of tubes having orifices, wherein the tubes are located at a top of the firebox below the top baffle; and   a rear pilot air manifold configured to receive air from the front of the furnace and conduct air along a second opposing side of the firebox, up the rear wall of the firebox, and into at least one hole defined through the rear wall of the firebox.   
     
     
         20 . The furnace of  claim 1 , further comprising:
 a first inlet through the front of the furnace communicated with the secondary air manifold; and   a second inlet through the front of the furnace communicated with the rear pilot air manifold;   wherein secondary air passing through the first inlet and the secondary manifold and rear pilot air passing through the second inlet and the rear pilot air manifold remain separated until the secondary air and the rear pilot air enter the firebox.