The integration of gas modular boilers with automatic control systems enables the system's water supply temperature to operate according to the heating curve (with an error ≤0.5°C), truly achieving "on-demand heating" and significantly reducing excessive heat loss and underheating issues. Single large boilers exhibit poor flexibility in load regulation, often relying on manual, staged coarse adjustments or methods like "high-low fire" and "peak fire." During the early and late stages of the heating season, when external weather conditions change frequently and significantly, the regulatory performance of traditional boilers makes it difficult for their actual output to match the required load, frequently leading to underheating or overheating—commonly referred to as the "supply-demand contradiction." This not only deteriorates heating quality but also causes unnecessary additional heat loss. According to domestic literature, the annual comprehensive load rate (including backup units) and thermal efficiency of domestic oil and gas heating boilers mostly remain below 45% and 72.7%, respectively, which is highly uneconomical. However, these two metrics have not yet garnered sufficient attention from experts. By advanced standards, the annual comprehensive energy utilization rate of such boiler systems is also very low. The modular design of Vandelit gas boilers determines the following characteristics: ① Each boiler serves as a backup for the others, greatly improving equipment and investment utilization rates as well as operational safety. If one modular boiler unexpectedly fails, the impact on heating is minimal—only 1/N (where N is the number of boilers). ② Excellent capacity expansion capability. As heating and domestic hot water loads in residential areas change (increase or decrease), the number of boilers can be adjusted at any time to meet heating needs with relatively low investment, unlike single large boilers whose capacity is difficult to modify. Gas modular boilers offer significant energy-saving effects: The system automatically adjusts the number of operating modular boilers based on temperature changes indoors and outdoors over time, ensuring that heat demand and supply remain balanced. Compared to large single boilers, energy savings of approximately 30% are achieved: (1) Single large boilers experience a 12% decrease in annual fuel utilization due to heat load fluctuations; (2) Single large boilers incur a 7% standby heat loss during heat load fluctuations; (3) Single large boilers suffer an additional 4.5% chemical combustion loss during heat load fluctuations; (4) The forced-draft combustion method of single large boilers increases electricity consumption by 2%; (5) Ventilation regulators equipped with modular boilers can save 2% on fuel costs; (6) The use of intelligent control systems in conjunction with modular boilers can reduce energy consumption by 2.6%.