Optimal characteristics of a heat exchanger for a chimney:

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The first two options are suitable for forming a water circuit and using heat in a heating system or hot water supply. The third design is more suitable for local air heating.

All types of heat exchangers have features that should not be ignored. If the heated medium is water, then the problem of excessive heat exchange arises. When the chimney is already hot and the stove is actively fired, the supply of cold water to the heat exchanger causes a sharp decrease in the temperature of the chimney walls. This mint data leads to condensation of moisture from the exhaust gases on the chimney walls, and, as a result, the channel quickly fills with soot and ash. To cope with this, it is necessary to reduce the heat exchange rate and the temperature difference.

Air heat exchanger

Along with high performance, it is very difficult to achieve durability. On the one hand, increasing the contact area of ​​the heat exchanger and the chimney increases the heat output, on the other hand, excessive heat intake threatens big problems up to the complete failure of the chimney.


The water circuit must be supplied with a separate heat storage tank, excluding the supply of cold water directly to the heat exchanger.
The heat exchanger design must be easily removable for cleaning and maintenance.
The heat exchanger capacity is selected based on the actual performance of the stove and chimney so that the gas temperature above the heat exchanger is sufficient to maintain draft.
As a material for the heat exchanger, it is better to choose stainless steel, which can withstand sudden temperature changes. The inner surface of the heat exchanger that comes into contact with smoke should be perfectly smooth if possible, so that condensate, even if it appears, falls into the condensate collector, without creating unnecessary problems.

Homemade heat exchangers for chimneys are often assembled without taking these requirements into account and without preliminary calculations, which causes a lot of problems, both with water heating and the condition of the chimney.