SZS series gas-fired boilers are the main energy-saving and environment-friendly boiler products in the market at present. In order to reduce the heat loss on the surface of the furnace body, the outer package of the gas-fired boiler adopts the whole frame structure, which reduces the connecting plate between the frame and the drum, and effectively reduces the heat loss caused by heat conduction. In addition, the outer guard plates of ZOZEN SZS series gas-fired boilers can be customized as needed.