The small iron stove did not realize the separation of the heating furnace and living space, prone to gas poisoning, very unsafe, the thermal efficiency is also very low, only 10 ~ 20%, it is recommended not to use.

According to Tsinghua University measured, the thermal efficiency of ordinary soil heating is only 30 ~ 40%, 60 ~ 70% wasted (see Tsinghua University Professor, Chinese Academy of Engineering Jiang Yi, edited by the Chinese Architecture Annual Development Report 2012), the main reasons for the following: 1, the exhaust temperature in the 300 - 500 degrees, the exhaust heat loss is too large: 2, the furnace body Heat loss is too large: 3, the thermal efficiency of the night sealing fire is 0.

At present, there is a heating furnace on the market, 1, with plate heat exchanger recovery of flue gas waste heat, the average exhaust temperature in 100 degrees Celsius, greatly reducing the exhaust smoke loss; 2, the furnace surface is designed as a water jacket, with a double-layer cover to reduce the heat loss of the furnace body. Its thermal efficiency is more than 80%, which can save half of the coal than the common soil heating.

Its schematic diagram is as follows: