There are several types of HVAC water systems that are designed with diversity. It could be a chilled water system, heat pump loop water system, heating water system, or (most commonly) a reheat water system. When diversity exists in an HVAC water system, the TAB of this system requires a system review and careful consideration of the approach to the TAB process.
The HVAC water system diversity is defined as the percentage difference in the pump capacity versus the connected load. For example, if the pump is sized for 300 gpm and the total connected load to all elements is 450 gpm, then the diversity of the HVAC water system is as follows: