Commercial Wood Boilers


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The E1000 model is a wood gasification boiler its available in both carbon steel and stainless steel and can heat up to 50,000 square feet. Made in Pennsylvania since 1981.

The Wood Gun line of boilers is one of the most fuel-efficient options on the market. While typical boilers waste two-thirds of your fuel’s energy potential, the wood gun captures and burns 66% more combustible matter, transforming it all into clean, consistent heat.

The Wood Gun was built to reduce the labor involved in standard maintenance…

All Wood Guns can handle full logs of up to 10 inches in diameter the Wood Gun spares you considerable wood-splitting work (length of firebox is shown below); with the ability to burn logs of up to 30% moisture, it cuts down on wood curing time; and, thanks to our signature Exhaust Scrubbing technology, the Wood Gun’s heat exchanger is self-cleaning—so the only cleaning you’ll have to do is weekly ash disposal.

The Wood Gun line can be used with any heating application (water-based, steam, forced-air).

Every Wood Gun can be ordered with an automatic feed option Which enables you to burn a variety of wood particle fuels, ranging from sawdust and wood chips to shavings, pellets, and other wood wastes¹. Additionally, with an AHS automatic feed system, only slight reconfiguration is required if you would want to burn log wood in the firebox.

How it works.


In a typical setup, particle fuel is conveyed by a blower or other means to a storage bin. Fuel is delivered on demand by means of an auger and a bin agitator which ensures a uniform discharge of material. A fuel level control system that incorporates a photoelectric sensor (3) monitors the height of the fuel in the fuel chamber (4) and activates the auger automatically. The photoelectric sensor consists of a receiver and a reflector mounted on the right and left side air-valves. The receiver sends a signal across the firebox which is reflected back by the reflector. When the fuel in the firebox reaches the level of the receiver, this beam is broken, and the sensor stops the auger.

Two key safety components of the AHS automatic feed system are the rotary airlock (1) and the fuel valve (2). Because it is necessary to maintain full control over the air intake of the boiler system to control combustion and enable off cycle, it is important that no air be able to enter the boiler through the top feed opening. This is accomplished using a rotary airlock, a device that works much like a department store revolving door. The fuel valve is a device that separates the fuel that is being burned in the fuel chamber and the fuel that is in the loading system, preventing the ignition of the fuel in the loading system.

The Wood Gun combustion chamber (5) is located beneath the fuel chamber and is composed of cast refractory sections which are positioned end to end to create several tunnels. This material has properties and texture similar to firebrick and helps to create the environment needed to achieve the high temperatures required for clean combustion. Slots in the refractory bricks provide passageways from the fuel chamber to the combustion chamber. Small fuel particles are prevented from falling through the slots by a fuel diversion structure (6). Various types of fuel diverter blocks are used depending on the size and type of fuel being burned.

All of the gas released during the gasification process is drawn down under the fuel diverter and through the slots in the combustion chamber where temperatures in excess of 2000° F are reached. The intense heat produced here radiates through the refractory lining (7) in the lower portion of the fuel chamber, evaporating moisture from the fuel and causing it to gasify (pyrolysis).

In order to draw the gases into the combustion chamber, a draft-inducing fan (8) is used. The negative pressure causes the fuel to effectively burn upside down. This is important because it allows fuel to be loaded continuously without extinguishing the fire. Once the gases are drawn into the combustion chamber, they pass through the firetubes (9) where most of the heat exchange takes place. On smaller Wood Gun models like the one shown, there is only one firetube. To increase the surface area available for heat exchange in the larger models, multiple firetubes are used. After the firetubes, the gases, which have cooled to about 350 F, are given a swirling action as they pass through the swirl chamber (10) and into the cyclone ash separator (11). Here, ash is removed from the exhaust air and deposited for easy disposal. Due to the unique design of both the refractory and the swirl chamber, exhaust passes through the boiler in a swirling motion that scrubs the inner chambers, preventing much of the buildup that could decrease efficiency. Exhaust air then exits through the top of the cyclone ash collector into the flue.

During off-cycle, wood gas inside the machine condenses on the inner walls forming a solid that will eventually flake off. It can then be re-combusted with the remaining fuel. Due to our large superheated refractory mass, reignition of the fuel occurs automatically after off-cycle when oxygen is reintroduced to the system.

¹A variety of fuels can be burned, including corncobs, nut hulls, cherry pits, and pelletized paper. Fuel sources are limited only by environmental concerns, such as the amount of ash produced, and fuel economy concerns, such as availability and BTUs per pound.

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  • Gasification
  • Range of Biofuels
  • Fuel-Efficient
  • Minimal Maintenance
  • Lifetime Durability
  • Versatile Applications
  • Automatic Feed Available
  • Standard ASME Certification
  • Made in the USA

Call (717) 987-0099 for pricing

Assembled Specifications



Typical Heating Capacity (square ft)


Standard Door Opening (in)


Firebox Capacity (cubic ft)


Firebox Length (in)


Approximate Water Capacity (gal)


Width (cyclone removed) (in)


Height (in)


Depth (in)


Flue Size (in)


Weight (without gas/oil backup) (lbs)


Domestic Coil

This Domestic Coil features a 100° F rise at 5 gallons per minute, 50° water inlet temperature and, 65 PSI water pressure. It is threaded into a 4 IN NPT threaded fitting provided on the boiler for this purpose.

Can be equipped with multiple coils as needed.

Smoke Exhaust Hood

The Smoke Exhaust Hood mounts over the loading door, capturing any smoke that may escape during the fuel-loading process. This smoke is then vented directly to the outside through a separate vent. When tolerance for smoke is low, the smoke exhaust hood is essential.

Low Temperature Shutdown

If all the fuel has been consumed in your boiler, the Low Temperature Shutdown Feature prevents the boiler from attempting to fire. This keeps the draft fan from blowing the remaining heat out through the flue.

Cycle Timer

This feature adds a timer that triggers the boiler to run for 10 minutes every 2 hours, even if there is no call for heat. This maintains an internal temperature above the kindling point, reducing the need to manually relight the unit during periods of low demand.

Oil/Propane/Natural Gas Backup

The Wood Gun wood boiler can be fitted with a backup fuel option. This requires a dedicated firing tube that must be built in during manufacturing.

Automatic/Manual Switching

For #2 fuel oil, the oil backup can function in an automatic switch-over scenario, with fuel oil taking over when the boiler has exhausted its wood fuel. For other fuels, such as natural gas or propane, switch-over is manual only.

Low Water Cutoff

A Low Water Cutoff senses the water level in the boiler’s vessel and will shut the unit down if the water level drops to an unsafe level. Available with automatic reset or manual reset.

Variable Speed Induction Fan

This enables the BTU output to be easily changed. This is accomplished by upgrading the 1-phase motor to a 3-phase motor and controlling the motor with a Variable Frequency Drive.

Automatic Feed

The Wood Gun™ series can be ordered with the ability to automatically feed itself wood particle fuels, such as sawdust, wood chips, shaving, pellets, etc. The Wood Gun™ auto-feed system loads the fuel into the firebox from the top. Only slight reconfiguration is required to still burn logwood in the firebox! This option comes with a photo-eye sensor, which controls when more fuel is needed, and an upgraded control center, which allows the user to easily control the entire system in one location. Touchscreen controls are available as well.

Additional Required Pieces:

  • Rotary Airlock – Rubber blades or machined stainless steel.
  • Fuel-Valve – acts as a second airlock, available in stainless steel.
  • Transition Tubes – available in stainless steel – connects the boiler to Airlock, Fuel-Valve, and Auger
  • Auger – available in nearly any diameter (4″, 6″, 8″, 10″) and any length
  • Diverter Bricks
  • Secondary Air Brick with cover

Low Pressure Steam

The Honeywell Aquastasts are switched out for Honeywell PressureTrolls and two Low Water Cutoffs are included. An automatic water fill valve and Steam Relief-Valve are also included. In some models, the vessel is changed slightly to allow for a larger steam shelf. The Wood Gun can produce steam up to 15 psi. To know what size steam boiler you need, first, figure the amount of BTU/hr needed for your home, then add 20% to the total. This extra 20% is only needed to create the initial head of steam.

Note: only available on Carbon Steel boilers.

Canister Pool Heater

Heat your pool with wood! Available in either Carbon Steel or Stainless Steel. This is a separate canister from the vessel.

Custom Engineering

At Alternate Heating Systems we have expert fabricators and engineers ready to tackle any design change! Whether it’s a custom bin, moving the cyclone to the other side, an extra load door, water storage tank, or whatever you may need to fit your application.