Free furnace free boiler rooms in Europe and America to introduce the most popular of the three return back fired wet back center, free expansion furnace, the furnace from heat stress, safe and reliable. Exhaust gases runs fire tube swirl combustion tube into the chimney from the fire, the second cyclone energy efficient heating, cleaning convenience. Mandatory Water circuit with obliged run water supply and return water by forced water circulation, avoiding hot and cold return water directly into the pipeline system. High effect heat insulation efficiency furnace insulation made of high quality fine wool light by Sowell, plus high-temperature baking paint shield, heat loss, high thermal efficiency. Furnace manufacturer in strict accordance with the national standard JB/7985-95 production, material selection of quality national standard boiler plate manufacturing. Door with total adjustment activities around door open, up and down adjustment and easy maintenance. Door seal with aeronautical engineering with high-tech materials - carbon fiber and ceramic fiber gasket preparation.