Wood boiler heat exchangers are a tool that allow a furnace, a wood furnace in this case, to transfer heat into a greater area. They do so by transferring the heat to a tank of water, and the boiling water then feeds through the exchanger device into a pressurized tube system set up in the intended area.The classic set up of the wood boiler is an iron, steel, copper, or alloy housing with an enclosed wood burning furnace at the bottom, and seated directly on top is a water tank. The water tank will have a cold water feed pipe flowing into it at the bottom, while it will have a hot water or steam pipe exiting from the top. From there the pipe will lead into the heating system within the area, often terminating in external radiators, the more modern of which will be connected to a thermostat, allowing for fine control of heat production.

Maintenance is a fairly simple task in the case of the wood boiler heat exchanger, as the system will noticeably leak in the case of a break, and there are no complex machined pieces that will need special service. One issue, however, is that if freezing temperatures are common in the area, a modified solution will need to be used in place of the water to prevent freezing the system, and causing damage to the boiler. Because of the pressure involved in the piping, a rupture of any sort can be dangerous, and the system should be depressurized before maintenance is attempted.

The actual heat exchanger portion of the system is the line between the pressurized network of piping leading to the radiator terminals and the furnace. It is usually a solid material allowing the heat energy to transfer from one liquid to another without mixing, or from one state to another, such as water to air heat exchangers to gas. The most common from for a wood boiler is a brazed plate, keeping the cold water at the bottom and the hot water or steam flowing into the heating system. This allows it to remain a fundamentally closed system, making it particularly energy efficient.