The arch of CDZL series hot water boiler adopts high long arc back arch, which makes the flue gas flow long, fuel combustion complete and combustion efficiency high. The boiler uses water sealing machinery to discharge slag, and the slag falls into the slag hopper through the back of the grate, which is convenient for centralized cleaning. The boiler is a three-return water and fire tube boiler arranged longitudinally. It is composed of the boiler body chain grate, pipe instrument, blower, induced draft fan, smoke duct and dust removal device, etc. The body and grate are assembled in factory. The combustion equipment adopts light chain grate, double-side air supply, and the grate is driven by a reducer and an electric motor.