The Portage and Main Ultimizer Quad Pass Heat Exchanger

Portage and Main Ultimizer Outdoor wood furnace’s design and robust, quality manufacturing ensure that their furnaces achieve hotter, slower and more balanced burn which means higher efficiency. An efficient burn requires a balance of three elements:
Fuel, Oxygen and Heat

What is a heat exchanger?

Simply defined, a heat exchanger transfers heat. In a Portage & Main outdoor wood furnace, this heat exchanger transfers heat from the firebox to water surrounding the chamber. How is the heat exchanger designed and constructed?

Portage & Main have a unique Quad Pass designed heat exchanger. The design includes a water-cooled baffle at the top of the firebox. The heat then moves to the heat exchanger which is surrounded and separated by water-cooled walls and dividers.
This design makes the transfer of heat extremely efficient.

Double welded boiler style joints are exclusive to Portage & Maine outdoor water furnaces. All parts are laser-cut for precision fitting which allows the bevel to be double welded for total penetration welds. The fire chamber and heat exchanger are made a quarter-inch w44 cold roll mild steel which eliminates the problems associated with other metals.

How does a Portage & Main heat exchanger work?

First: After the fuel, heat and oxygen mix to create a balanced burn, some heat energy is transferred first to the water jacket surrounding the top of the firebox.

Second: Air is introduced above the fire which help burn the smoke and gasses. There is a baffle near the back of the fire chamber which serves a dual purpose. The baffle is water-cooled so absorbs heat but also traps the hot gasses and smoke. This trapping of gasses, oxygen and fire creates combustion storms which causes the fire to burn hotter.

Hotter burn = complete combustion = best efficiency

Three and Four: After combustion, this exhaust heat then travels horizontally through the heat exchanger at the top of the furnace. This is an industry-leading, 180⁰ reverse turn, water-cooled chamber that runs the full length of the furnace. This results in the largest heat transfer area of any updraft boiler design.

The Portage and Main chimney exit out the back of the furnace versus cutting it short out the top like other furnaces. This added length means more heat absorbed to the surrounding water and less heat escaping. Its dual chamber design, fully surrounded by water, and added length results in maximum heat transfer resulting in low temperature chimney escape.