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An outdoor furnaces uses water to transfer wood heat from the outdoor boiler to a home, shop or any other location that requires heat. The drawings below detail various plumbing concepts that can be used to supply heat and domestic hot water. Several types of heat emitters are covered. Click on the drawing or links below to open a larger image file.


Notice: The drawings provided show system piping concept only. The installer is responsible for all equipment and detailing required by local codes.

Closed Indoor system – Heat Exchanger Detailing

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This drawing details the components required to create a closed system indoors.

Polar recommends all installs include a heat exchanger between the outdoor wood furnace and the indoor distribution system. This becomes more important as the indoor system becomes larger and more complex.

Central Air – Closed Indoor System

This drawing shows how to hook up to central air only with a closed system.

In this situation the pump on the load side of the heat exchanger or the fan in the central air furnace can be switched on and off by a room thermostat.

Central Air & DHW – Single Pump – Open System

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This drawing shows the simplest way to connect an outdoor wood furnace to central air as well as the domestic hot water tank.

In this concept the main pump at the heater is always on and circulating hot water.

Central Air & Domestic Hot Water – With Diverter Valve

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This drawing shows a closed system in which a diverter valve supplies hot water to the central air furnace radiator only when there is a demand for heat from the room thermostat.

Pros: More precise and more stable temperature control inside building. Central air fan never shuts off and continuously circulates air in building creating more constant temperatures inside the building heated.

Multiple Types of Heat Emitter Connections

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This drawing shows how multiple types of heat emitters can be connected.

For a more complex system like this Polar Furnace strongly recommends a heat exchanger between the outdoor wood furnace and indoor system. Also when distributing to heat emitters higher than the water level in the furnace a heat exchanger is also strongly recommended to minimize the occurance of air traps in the system.

All Installation Concept Drawings PDF

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This is a pdf file including many more installation concept drawings.