Outdoor Wood Boiler 400 SS

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Outdoor Wood Boiler 400-4S

The HEATMOR™ 400 Stainless Steel Smart Stove (400-4S) represents the culmination of over two years of research and development in the design of an outdoor furnace that meets the Heatmor exceptional standards of convenience, durability, reliability, and at the same time meeting the strict emission standard established by the US EPA OWHH Voluntary Phase II Program. What truly makes the HEATMOR™ 400-4S stand out is that it is designed and manufactured with proprietary software and a secondary air wing located for optimum air flow resulting in the best and most efficient burn possible.

Competitors may design their units to simply pass the EPA tests, then in real world applications their units may fail to perform well, but at HEATMOR™ we have designed our unit to not only pass the EPA test but also ensure that you get a quality burn no matter what type of wood you are burning. The 400-4S also has a high efficiency flue so you get the most heat from your wood. There is no catalytic converter and complicated downdraft system. It is our custom designed electronically controlled airflow, combined with a high efficiency flue to give you the cleanest burning, highest efficiency stove on the market, while still offering the customer solid assurance in a quality product. The 400-4S is designed to be a one piece all Stainless Steel body to utilize the best manufacturing practices while delivering the quality and product reliability you expect from Heatmor.

We are so confident that the Heatmor 400-4S is the most efficient stove that we made the firebox smaller. You WILL burn less wood. We are also so confident in the quality design and construction of the 400-4S model that we stand behind it with the Heatmor Limited Lifetime Warranty (see below).

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Performance Features

  • Over/Under Forced Air Draft - increases efficiency of burn over natural draft systems
  • The secondary air wing design directs the secondary air to the optimum location in the firebox and the electronically controlled airflow provide for the cleanest, hottest and most efficient burn.
  • Ceramic Lined Firebox allows for a hotter, more complete burn.
  • Ash Pan Chamber & Cast Iron Grates in the firebox provide efficient combustion that burns wood into a find ash providing for easy ash removal.
  • High Efficiency Exit Flue - so you get the most heat from your wood.
  • Rear Access Door - for easy access of plumbing, maintenance and AQUASTATS. Aquastats are used to regulate the temperature of the water.
  • Bladder System - reduces water loss.

Safety Features

  • Outer Door Locks - prevent unwanted access.
  • Our Non-Pressurized System - prevents pressure build-up in the water jacket and increases safety.
  • Insulated Outer & Inner Firebox Door - provide cool surfaces for extra safety protection when accessing the firebox.
  • Automatic Fan Switch & Inner Door Safety Latch reduces flashback when opening furnace door.
  • The Attractive Insulated Housing (R-19 Sides, R-38 Roof) protects electrical and plumbing components while providing cool surfaces for children or a passerby. Fiberglass insulation is non-flammable (Unfaced insulation passes ASTM E 136 test for non-combustibility.)
  • Relief Vent - utilizes a weighted rubber stop to prevent pressure build-up in water jacket and greatly reduces evaporation.

Commitment to Quality

  • 10 & 11 Gauge 409 Stainless Steel is used in all assemblies that come in contact with fire and water, protects against corrosion and warpage increasing the life of your furnace up to three times longer than mild steel. 11 Gauge is used in the flue for the most effective, efficent heat transfer.
  • Water-Cooled Ash Pan - decreases warpage and increases heat transfer to water
  • Stainless Steel Chimney lasts longer than mild steel.
  • Water-Cooled Firebox Door, excclusive to Heatmor™, decreases warpage and increases heat transfer effciency to water jacket.

Convenience Features

  • Smoke, ash & wood mess is outside the home.
  • Can use unsplit wood up to 41"
  • Long Burn Times - load no more than twice a day.
  • Large water-cooled firebox door allows for easy loading
  • Wired for easy electrical hook-up (110v)
  • Multiple hook ups allow you to heat more than one building/heating system from the same furnace including your home, domestic hot water, swimming pool, hot tub, garage, workshop, greenhouse or farm shop.
  • Ash pan system provides for easy removal of ash from the rear of the furnace. No more shoveling out the firebox. No need to let fire burn out to remove ashes.
  • Easy Access Flue for general maintenance.
  • Electronics Access for general maintenance and information.

We are often asked which colors are available for our products. One great feature is that you can choose from 22 attractive colors to choose from at NO ADDITIONAL COST! This allows you to create an attractive color combination that complements the color scheme of existing buildings such as your home, garage, shop etc. To see the name of the color, simply hover over the image.

You can choose from our 22 different color choices as seen here for the siding. The trim and roof of the unit are black.

Colors may vary due to monitor resolution. For an actual color swatch, please contact us for an actual example.

*Camouflage available on residential models only and subject to surcharge.


Our Limited Lifetime Warranty which covers defects in materials as well as both corrosion and workmanship is by far one of the best in the industry. Because we have such great confidence in our product, we are able to offer you one of the most comprehensive warranties in the industry. Heatmor is the only company in the industry who provides onsite service to your unit. The key to researching warranties is reading the fine print. Please click on the warranty to the right for a larger view.

Burn Unseasoned Wood
Unseasoned Wood

The only boiler on the market that allows you the ability to burn unseasoned wood!

Large Ash Auger System
Large Ash Auger System

Ash Auger Chamber & Cast Iron Grates in the firebox provide efficient combustion that burns wood into a find ash providing for easy ash removal.

Utilizing Firebrick

The two-inch thick firebrick allows the fire to reach higher combustion temperatures in order to facilitate a more complete burn.

Strongest Warranty on the Market
Strongest Warranty

Be safe with our limited lifetime warranty! It has proven to be one of the strongest on the market, and assures you will have many great years of wood burning.