5.3102.9 Installation and Control of Variable Frequency Drives (Hot Water)

Hydronic Heating (Hot Water and Steam)
Equipment Installation
Desired Outcome: 
Electrical consumption reduced while matching water flow to demand
Evaluate existing pumps and motors

Motors will be evaluated to determine compatibility with variable frequency drives (VFD)

Load profile and source equipment will be analyzed for use of VFD to provide variable water flow to load

System valves will be surveyed to identify two-way and three-way valve locations

Control strategy will be determined (e.g., differential pressure control, pressure control, differential temperature control, summer/winter settings)

Ensure existing motors and system are compatible with VFD operation

Remove and replace motor

If removal and replacement of motor is required, the power supply will be disconnected, and the existing motor will be removed and replaced with motor suitable for VFD operation

Provide motor suitable for VFD operation

Remove and replace motor starter

Power supply will be disconnected; existing starter will be replaced with VFD in accordance with manufacturer specifications

Install and connect VFD

Install required sensors

Implement the following VFD control strategies:

  • Feedback sensors will be installed in accordance with manufacturer specifications at locations that will optimize chosen control strategy
  • Feedback sensors will be wired to VFD in accordance with manufacturer specifications

Ensure sensors are installed to optimize VFD operation

Modify system to VFD control

System will be modified to best utilize VFD operation (e.g., conversion of three-way valves to two-way valves), as well as to safely operate boiler

Ensure system is compatible with VFD operation

Restore power supply to VFD, and verify operation of VFD and pump

Power supply will be restored

VFD will be shown to be capable of operating pump

VFD will be shown to be capable of receiving sensor signals

Ensure VFD is ready for setup

Initial setup of VFD

VFD parameters will be set up to accept feedback from sensors, dependent upon chosen control strategy

Maintain minimum system heating requirements with reduced electrical energy use

Educate building operations staff

Building operations staff will be educated to operate VFD systems, including sensor location, control operation, and set points

Ensure continued optimized performance