The cast iron gas-fired modular atmospheric hot water boiler, developed by Shaanxi Deli Energy, is a product with independent intellectual property rights that leads international standards, holding national patent numbers 201320778345.0, 201310632249.X, 201320784596.X, 201320778344.6, and 201320784600.2. Its core component features a uniquely designed, high-quality cast iron movement mechanism developed in-house, ensuring a service life of over 50 years and adaptability to diverse user needs. Multiple units can be combined in parallel, leveraging modular advantages to achieve fully automated, staggered startup and shutdown based on heat demand, eliminating the need for dedicated personnel. With strong fuel adaptability, it supports natural gas, liquefied petroleum gas, coalbed methane, biogas, and other fuels, effectively addressing gas source and type shortages in various regions. It can integrate with central air conditioning, solar energy, and underground heat sources for complementary heating, making it widely applicable for heating and domestic hot water supply in residential communities, shopping malls, villas, hotels, spas, schools, and hospitals. This multifunctional equipment is energy-efficient, highly efficient, quiet, environmentally friendly, and pollution-free. The modular design of the gas-fired boiler, combined with intelligent software coordination and control, enables flexible, efficient, and economical operation of the boiler system. For instance, a heating station covering an area of 25,000 m2 can utilize 12–18 modular boilers as the heat source. Under manual adjustment, the minimum output regulation accuracy is 8.3%, with a temperature adjustment range of 2.0°C. Under automated software control, the minimum output regulation accuracy improves to 4.0%, with a temperature adjustment range of 0.5°C. This demonstrates the significant advantages of gas modular boiler systems in enhancing heating quality, reducing operational costs, and minimizing energy consumption. Regardless of seasonal conditions, each operating modular boiler operates at full load, while non-operating units consume no energy, ensuring the entire system runs at high efficiency. According to actual customer data analysis, combining modular boilers with an automatic control system significantly reduces excess heat loss, achieving overall energy savings of 15.4%. Gas modular boilers avoid issues such as low annual thermal efficiency, load rate, and comprehensive energy utilization. This is due to their inherent characteristics: under controller linkage mode, multiple boilers can operate in coordination. Based on predefined heating temperature curves and parameters such as indoor temperature and building thermal inertia, the system intelligently determines the number of boilers to start or stop, achieving a near-unattended operation mode. Throughout the process, each operating boiler maintains full-load, high-efficiency operation (above 91%), effectively eliminating the widespread issues of low thermal efficiency, load rate, and comprehensive energy utilization commonly seen domestically. This results in notable economic and social benefits.