Wood Gun

Wood Gun™ High Efficiency Gasification Wood Boiler

The Wood Gun™ wood gasification boiler by Alternate Heating Systems utilizes the most advanced technology in wood burning and is perhaps the most efficient wood burning device on the market today. This uncompromising multifuel system is ideal for any residential application where wood or wood by-products are used as fuel. The AHS Wood Gun™ is available in residential sizes ranging from 100,000 to 250,000 BTU’s and commercial sizes up to 1,000,000 BTU.

  • Automatic cycling on and off in response to heating or hot water demand.
  • Domestic hot water coil provides abundant quantities of hot water.
  • Exceptionally safe and clean burning. The use of dense refractory material cast into specific shapes causes complete combustion to occur at temperatures of up to 2000° F.
  • When operated properly in the gasification mode, visible smoke is eliminated and creosote formation inside the chimney is prevented.
  • The large cyclone separator removes most of the fly ash resulting in very
    low emission.
  • Spontaneous re-ignition of the wood will occur after an off period of 2-4 hours
    Re-ignition is dependent on the refractory temperatures.
  • Automatic fuel delivery systems are available for wood waste products such as sawdust, shavings, woodchips and densified biomass. These are designed more for industrial/commercial applications rather than residential.
  • Wood Gun™ readily adapts to new or existing hot air systems through the use of a heat convection coil.
  • The design maintains all heated walls at the same temperature using a "water wall". This constant temperature eliminates stress fractures caused by differences in temperature between components of the boiler thus increasing it's life. In addition, this design produces greater efficiency because heat that is normally lost through a drywall is captured in the water wall.

Model: E100 E140 E180 E200 E250
BTU/H (Max.) Wood 100,000 140,000 150,000 185,000 230,000
Oil (optional) ** 80,000 130,000 160,000 160,000 230,000
Heating Surface 30 ft2 39 ft2 46 ft2 55 ft2 70 ft2
Water Capacity 60 Gal 80 Gal 80 Gal 95 Gal 140 Gal
Fire Box Capacity 6.5 ft3 10 ft3. 14 ft3 18 ft3 22 ft3
Max. Log Length 26" 30" 30" 38" 46"
Door Opening 14" x14" 14" x14" 14" x14" 14" x14" 14" x14"
Height 58" 64" 66" 66" 74"
Width 26" 26" 31" 31" 31"
Depth 44" 48" 48" 56" 66"
Flue Size 6" 6" 6" 8" 8"
Weight (lbs) 1,400 1,650 2,100 2,400 3,000
Domestic Coil Gal/min (Optional) 5 5 5 5 5
*Rec. Sizing: for 8-12
hour burn cycle (BTU/hr)
70,000 100,000 140,000 175,000 220,000
*Average hourly BTU output is based on a 8-12 hour burn cycle

Model: E500 E1000
BTU/H (Max.) Wood 500,000 1,000,000
Net Steam Rating (BTU/H) 376,000 752,000
Heating Surface 116 ft2 192 ft2
Water Capacity 210 Gal 435 Gal
Gas/Oil Chamber (water capacity) 16 Gal 50 Gal
Height 90" 102"
Width 34" 48"
Depth 72" 78"
Flue Size 8" 12"
Weight (w/o gas/oil - lbs) 4,500 9000
ID Fan .75 HP 2.0 HP
Minimum Boiler Room (w/o Gas/Oil) 12'x15' 16'x16'
Minimum Boiler Room (with Gas/Oil) 14'x15' 16'x18'
Load Door 18"x18" 18"x18"

How it Works
Wood gas is produced by applying heat to wood, a process called pyrolysis. The wood gas is drawn through the bottom of the firebox and into our uniquely designed refractory by an induction fan. The gases are combined with oxygen and combusted in the refractory. The super heated gases pass through the interconnected refractory tunnels and in to our uniquely designed swirl chamber. This is where the bulk of heat exchange takes place. The superheated refractory then continues to gasify the wood remaining in the firebox. After combustion the residual ash is combined with high velocity air flow to scrub the heat exchanger preventing any build up. This process allows us to maintain an unparalleled consistency in heat exchange. Most ash exits the unit and is collected in the cyclone ash separator for fast and easy removal.

The Wood Gun™ cycles on and off much like an oil or gas fired boiler. During the off cycle, fuel is not consumed because oxygen is not present in the combustion chamber. With the large superheated refractory mass, re-ignition of the fuel (usually occurs up to 5 to 6 hours later depending on boiler size) automatically when a drop in water tempurature signals the need for heat.

During the off cycle, wood gas inside the firebox condenses on the inner walls forming a solid that will eventually fall off. This combines with the remaining fuel thus adding energy that in many other boilers goes up the chimney.


Carbon vs. Stainless Steel in our Wood Boilers

The internal surfaces of a Wood Gun™ Wood Boiler include any surface touched by the flame, smoke, wood or exhaust.  The internal surfaces may be manufactured with carbon steel or stainless steel - it's your choice.  We recommend stainless steel because carbon steel will show deterioration within 10 years though the unit may continue to function for as much as 20 years.  We have had stainless steel boilers in service for 20 years, and they show no sign of deterioration.  We use 1/4" thick 304 stainless steel (as opposed to 409) for unsurpassed quality.

Stack Temperature

Exhaust stack temperature is an indicator of transfer efficiency. During combustion, temperatures of around 2000° Fahrenheit can be obtained. Amazingly, our exhaust stack temperature ranges from about 260-300° Fahrenheit. This stack temperature is unheard of in the industry. The Alternate Heating Systems WoodGun™ is truly the pinnacle of wood fueled heating devices.