Variable Speed Pump Controller

Installing a variable speed pump controller is a must for any “green” potable or hydronic water pumping system, or indeed for anyone who wants to save money and make their system long-lived and more efficient.

Systems that use out-moded controllers are energy hogs. Today, according to the US Department of Energy, pumping systems alone account for 20% of the world’s energy used by electric motors. Imagine the energy saved if all these systems switched to “intelligent” controllers that precisely match pump speed to real-time demand. And the benefits would go beyond energy savings to include improved pump performance, greater reliability, and reduced life cycle costs.

Central to a variable speed pump controller is the variable frequency drive (VFD), sometimes called an adjustable frequency drive, variable speed drive, or AC drive. There are many kinds of VFD, but the idea behind all of them is to automatically and precisely control the speed of alternating current (AC) motors. Most VFDs work using a two-step process: ordinary AC power enters the drive and is converted (by a “rectifier”) to direct current (DC). An “inverter” then turns the DC into an adjustable frequency AC output to run the pump motor. Sensors tell the rectifier and inverter exactly what AC frequency and voltage is needed at any moment.

We all know that smooth acceleration is better for a car’s engine than jerky starting and stopping, and the same is true for pump motors. That’s why pumps that used variable speed controllers last longer than pumps that run with pressure switches and simple on/off commands. Variably controlled pumps are also quieter (there’s no water hammer caused by abrupt operation) and they put less stress on pipes and valves.

A leading manufacturer of water supply components, ITT RCW engineers a host of variable speed pump controllers, with value-added features specific to their application. These controllers can be small devices that attach directly to pumps and circulators, mounted control boxes that link up to a hydronic or potable water pumping system, or part of a water supply “set” that also includes all necessary pumps, motors/drives, and sensors. Ask your ITT RCW dealer, distributor, or installer for more information on which controller is the right solution for your system.

Controllers for Hydronic Heating and Cooling Systems

For water-based (hydronic) heating and cooling systems, controllers are primarily used to precisely mix water in the primary loop with water in a secondary loop, or zone. They can also be part of a “weather-responsive” system, with the controller adjusting the system to the outside temperature, in effect re-sizing the system to match environmental conditions.

“Snap-On” Hydronic Controllers—These small controllers are designed to snap onto ITT RCW wet rotor circulators that pump water from a primary hydronic loop around secondary loops. These all-in-one controllers can be used as set point controllers or as signal-followers. They can be used both for primary-secondary water injection and for bypass boiler injection.


Multi-Function Zone Controllers—Ready-to-install controllers for residential and commercial hydronic circulators, they are packed with value-added features, including:
Priority function—enables the domestic hot water zone to have priority over heating zones for short periods.
Post-purge timer—runs the circulators after the thermostat opens to extract maximum energy from the boiler.
System exercise—runs each circulator briefly after 72 hours of inactivity.
Mixing reset—varies the speed of the pump to maintain optimum radiant loop temperature relative to the outdoor air temperature. The boiler return temperature is also monitored to ensure that the minimum water temperature is not violated.


Controllers for Potable Water Systems

The problem? A conventional well water supply system uses a pump with a constant speed motor to fill a large tank. When a fixture or faucet is opened, water is delivered at a specific pressure. As the tank empties, the pressure drops and a pressure switch turns the pump on to refill the tank. And so it goes—as more fixtures are used, the system cycles more quickly, and water pressure can fluctuate dramatically.

The solution? A variable speed pump controller that intelligently monitors system demand and speeds up or slows down the pump to maintain constant water pressure.

Submersible Well Pump Controllers—Pre-select your system pressure, and just walk away! You’ll never have to worry about water pressure again. Plus, ITT RCW submersible well pump controllers are packed with benefits, including:
Smaller tank required—system size and overall footprint are reduced.
Versatile—use for well pumping, fire suppression, water treatment, irrigation, and many more applications.
Self-diagnostic—sensors monitor the system for a dry well, loss of prime, short circuits, high temperature, and more.


“Snap-On” Controllers for Well Pumps—These small-but-smart controllers can be mounted to the fan cover of pump motors. Ideal for modestly sized residential systems, they can run a “slave” pump and feature sensors for low water and motor temperature.


Pre-Packaged Controller System—This complete residential constant pressure system—for municipal supply customers and also for wells—includes a self-diagnostic variable speed controller, pump, motor, pressure tank, pressure transducer, piping tee, pressure gauge, and wiring with flexible conduit. The system is connected to the plumbing after the municipal water meter. A sensor compares pressure in your pipes to the pressure you want. If main line pressure drops, the controller turns on the pump and dials in the exact speed required to give you just the right amount of water pressure.


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