Monday, April 15, 2024

Portage & Main Economizer IDM 100 Furnace - Discontinued

Portage & Main Economizer IDM 100 Furnace - Discontinued

This product has been discontinued and all inventory has been sold. This is an informational page for those who have already purchased the unit. 

The Economizer IDM 100 indoor water furnace by Portage and Main uses the high temperatures obtained from wood gasification and transfers this heat into water using the highly efficient scotch marine tube heat exchanger.  

This process, wood gasification, produces a cleaner burn resulting in reduced emissions, less creosote build-up, less ash in the unit and less wood consumed.

IDM stands for indoor model and is easily installed in wood sheds, garages barns, shops etc.

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Highly efficient combustion is achieved in the Economizer IDM 100 by using the wood gasification process. Wood is burned in the furnace’s primary burn chamber and the IDM's negative pressure system creates a draw to mix oxygen with the combustible gases completing the gasification process. 

Refractory brick lining of both burn chambers help produce then absorb the high temperatures generated.  Maximum heat extraction is then obtained by passing the exhausting air through vertical and horizontal passes heating the water in the surrounding water jacket quickly and efficiently.

The IDM 100 boiler / furnace unit has many features, listed below, that are signature to Portage and Main’s highly efficient, long lasting furnaces.



The Economizer IDM 100, as all Portage and Main models, has a rounded firepot with Over Under Air.

Large amounts of pre-cast, stainless steel reinforced refractory brick line the fire chamber.

Common refractory brick is used in the reaction chamber, where gasification occurs, and can be removed, replaced or rearranged.

Heat from the gasification process in the lower reaction area is transferred behind the refractory brick into the water jacket.


The extensive surface area supplied by the scotch marine multi-pass tube heat exchanger provides heat recovery into water.  The heat exchanger of the Economizer IDM 100 consists of four 2” vertical tubes (first pass) and eight full length 2” horizontal tubes (second and third passes).

Cleaning fire tubes is a breeze with included cleaning brush.


Pump install area is easy to access in the back of the boiler and interior space is protected by insulated doors which are lockable.  Economizer IDM 100 has a single pump hook up, though extra pumps can be tied in.  (Pumps are not included with the boiler.)

Also protected by the back doors are the furnace temperature controls: Honeywell Digital Controls with safety high limit setting and low water shut-off.

Doors are insulated, charge door with extra thick refractory brick, or double stainless steel and have adjustable latches and hinges.  The safety latch doors seals with top quality industrial core gasket for a long-lasting positive seal.  The furnace itself is well insulated with Roxul insulation.

Convenient Float makes it easy to see the water level.

The Econonmizer IDM 100 has a stainless steel cover.


Firepot and heat exchanger are made of 1/4” W44 cold rolled steel.

Inside water jacket is made of 1/4” cold rolled steel and the outside water jacket is made of 3/16” cold rolled steel.

All Parts are laser cut and are boiler style welded – welding inside and outside helps prevent weld corrosion.

Specifications Economizer IDM 100
Maximum Furnace Output (BTU/hour) Up to 140,000
Heating Area (sq. ft.) 3,000
Size Total W x D x H 29.5" X 40" X 66"
Shipping Weight (lbs) 1600 lbs
Chimney Size 6”
Door Size W x H 12.5” x 14”
Fire Chamber W x H x L / Cubic Feet 20” x 30” x 20” / 7
Water Capacity (US gallons) 70
Horizontal Fire Tubes 8 (2 diameter)
Vertical Fire Tubes 4 (2" diameter)
Maximum Log Length 18"
Split or suggested Log diameter 4 "to 5"
Suction Motor Negative Pressure
Electrical Requirement 110/120 Volt
Heat Exchanger Triple Pass
Limited Warranty Lifetime

Portage & Main Economizer IDM 100 Furnace - Discontinued

Portage & Main Economizer IDM 100 Furnace - Discontinued

Portage & Main Economizer IDM 100 Furnace - Discontinued

Portage & Main Economizer IDM 100 Furnace - Discontinued

Portage & Main Economizer IDM 100 Furnace - Discontinued

*Shipping is not included.

Please call or email for pricing with shipping quote.


Portage and Main Economizer IDM 100


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