How should the vertical zoning of the air-conditioning water system in a super high-rise hotel be designed? How is the zoning pressure determined?
I am an HVAC expert. The issue you raised regarding the vertical zoning design of the air-conditioning water system in a super high-rise hotel is central to system safety, energy efficiency, and O&M costs. Improper zoning may lead to overpressure damage to low-zone equipment, cavitation in the high-zone system, or uneven cooling and heating, directly affecting the comfort and reliability of hotel operations. According to Article 8.2.3 of GB 50736-2012 "Design Code for Heating Ventilation and Air Conditioning of Civil Buildings" and Article 8.5.7 of GB 50019-2015 "Design Code for Heating Ventilation and Air Conditioning of Industrial Buildings," the zoning of an air-conditioning water system must be comprehensively determined based on equipment pressure-bearing capacity, system working pressure, and building height.
**Key principles of vertical zoning design**:
1. **Determination of pressure thresholds**: Zoning pressure mainly depends on the pressure-bearing capacity of terminal equipment (such as fan coil units and cooling coils of air-handling units). Conventional equipment has a pressure-bearing capacity of 1.0 MPa (about 100 m water column), but super high-rise hotels often use custom equipment with a pressure-bearing capacity of 1.6 MPa or 2.0 MPa. According to Article 8.2.3 of GB 50736, the system working pressure shall not exceed the allowable working pressure of the equipment. It is generally recommended to control the static pressure difference of each zone within 80-120 m water column to leave a safety margin.
2. **Zoning methods**: The commonly used modes are "high zone + low zone" or "high zone + middle zone + low zone." If the building height exceeds 200 m, three-stage zoning may be required. Zoning interfaces are usually set at equipment floors or refuge floors, using these floors as heat exchange stations or booster pump rooms.
3. **Pressure control measures**: The high-zone system requires pressure-reducing valves or plate heat exchangers to isolate pressure. For example, install self-operated differential pressure control valves on the low-zone return water pipe to ensure that the head of the high-zone water pump does not affect the low zone. At the same time, install safety valves at the interface to prevent water hammer impact.
**Practical engineering case**: I once participated in a 300 m super high-rise hotel project, which adopted three-stage zoning: "low zone (floors 1-30, 0.8 MPa) + middle zone (floors 31-60, 1.2 MPa) + high zone (floors 61-80, 1.6 MPa)." The low zone was directly supplied with cooling from the basement cooling plant, while the middle and high zones were isolated from primary water through plate heat exchangers on the refuge floor, with secondary water circulation pumps located on the refuge floor. During design, according to Article 8.2.4 of GB 50736, expansion tanks and make-up water pressurization devices were installed on the secondary side of the heat exchangers to ensure stable pressure in the high-zone system. In actual operation, the pressure-bearing capacity of terminal equipment in the high zone was 1.6 MPa, and no overpressure accidents occurred.
**Summary**: The vertical zoning of the water system in a super high-rise hotel should be based on equipment pressure-bearing capacity and building height, adopting a "zoning + heat exchanger isolation" or "zoning + pressure-reducing valve" scheme to ensure that the working pressure of each zone is lower than the allowable value of the equipment, while also considering pump head, pipe wall thickness, and safety valve settings. The above are reference opinions. The actual project situation still needs further comprehensive evaluation and implementation in combination with specific operating conditions, site conditions, and other factors.