This standard specifies the terms and definitions, models and basic parameters, basic requirements, technical requirements, inspection and test methods, inspection rules, paint, packaging, marking and random documents, and quality commitment of gas (oil) vacuum hot water units. This standard applies to vacuum hot water units (hereinafter referred to as units) that use natural gas or light diesel as energy, water as the heat medium, and the internal working pressure of the host is negative pressure, which can produce heating hot water and sanitary hot water simultaneously or separately.