High-Rise Non-HVAC Services > Variable Speed Domestic Water Booster Pumps

Existing Conditions

Two xxx hp domestic water booster pumps supply the necessary water pressure for the buildings. These pumps are designed to supply up to xxx ft.wc. of additional head at a flow rate of xxx usgpm

Pressure reducing valves (PRVs) at the outlet of the pumps substantially reduce the pressure, so that only about xxx ft.wc. is actually added.

The pressure drop across the PRV’s results in a significant drop in efficiency.

Retrofit Conditions

We recommend installing variable speed drives and inverter duty motors on the two booster pumps. Any PRV’s on the main line leading to the penthouse should be opened completely or entirely removed to reduce the system losses.

We recommend installing a pressure sensor on the piping in the penthouse, and controlling the VSD’s to maintain a certain pressure (say 20 psig).

Further Benefits

Application Details

Placing the sensor at a high point rather than near the pumps will maximize savings by allowing the pressure setpoint to be as low as possible, without having to add a safety factor for greater pressure losses during maximum flow periods.

Issues and Concerns

References

Analysis

Minto Management did a study in xxx which found an payback for the measure ranging from xxx years to xxx years with an average of xxx years.