Energy-saving and environment-friendly cast iron module boiler

The utility model provides an energy-saving and environment-friendly cast iron module boiler which comprises a boiler body, a heating cavity is formed in the inner upper portion of the boiler body, a heat-conducting medium and a heat exchange pipe set are arranged in the heating cavity, a combustion cavity located below the heating cavity is formed in the boiler body, an energy-saving combustor is arranged in the combustion cavity, and a water inlet part and a water outlet part of the heat exchange pipe set both extend out of the boiler body. The water inlet part is simultaneously connected with a water inlet pipe and a first valve, the water outlet part is simultaneously connected with a water outlet pipe and a second valve, a circulating pump, a dosing device and a filtering device for filtering scale are connected in series between the first valve and the second valve, a third valve is arranged on the water inlet pipe, and a fourth valve is arranged on the water outlet pipe. Descaling work can be carried o