Water Pressure Requirements in High-Rise Buildings

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Water Pressure Requirements in High-Rise Buildings

In high-rise buildings, a properly designed hot water distribution system presents several challenges. A compliant system requires a minimum pressure at every fixture. Per standards and guidelines, the minimum pressure is generally around 200 kPa (2 bar or 25 psi). Meeting the minimum pressure requirement in a high-rise building, requires a pump because water pressure drops approximately 10 kPa (0.1 bar or 1.5 psi) for every meter that it rises.

Although the pump helps meet the minimum pressure requirements for the higher floors, it causes problems elsewhere because the maximum pressures must not be exceeded that are generally around 500 kPa (5 bar or 80 psi). Without proper design considerations, achieving the minimum pressure at the top of the building, almost certainly means exceeding the maximum pressure at the bottom of the building.  The Figure shows an example of the pressure drop between floors in a high-rise building.

How to Design Hot Water Recirculation Systems in High-Rise Buildings (h2xengineering.com)Image source: How to Design Hot Water Recirculation Systems in High-Rise Buildings (h2xengineering.com)

Without appropriate design considerations, meeting the minimum pressure requirements at the highest floor means exceeding the maximum pressure limits at the lower four floors.

The use of pressure reduction valves (PRVs) and pressure zones (where the pressure is within a desired range) helps to provide a balanced system in high-rise buildings and avoids long wait times to receive hot water.

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