I recently had the opportunity to try out Taco’s new Viridian variable speed pumps on several projects. I have installed a total of six pumps on three projects. This pump uses ECM technology to vary the speed of the pump to match the load.
On two projects, I used the Viridian pumps on the geo loop fields. We used them in tandem to provide standby capability in the event one pump fails. The integral control board has this capability eliminating the need for an outboard control.
The pump has several operational modes but we chose the delta-P operating parameter with a remote enable signal to turn on the pump. The pump provides flow to the loop field and multiple geothermal heat pumps (six on one project, nineteen on the other project).
The Viridian will vary its flow as geo units come on line and then cycle off. A two-way motorized valve at each geo unit controls flow. The ability of this pump to vary its flow eliminates the need to bypass flow through three-way valves or through pressure actuated bypass valves. This simplifies piping and allows the pump to operate at the most efficient point on its pump curve.
For the horsepower and flow, I found these pumps to be compact, which is always a plus when working in tight mechanical rooms. They are also very quiet. When operating at a lower flow rate, I had to put my ear to the motor to confirm it was operating.
On another project, we used a smaller Viridian pump to feed 18 hot deck coils on air handler units. Required flow will vary greatly depending on how many air handlers are calling at one time. If you listen closely, you can hear the motor ramp up or down and flow requirements vary. These smart pumps also have an RJ45 Ethernet port which allows you to connect a laptop, router or network. I’ve yet to delve into this aspect of control, so I can’t report on this feature.
The six pumps we have currently installed and running have exceeded expectations and I plan to use this pump on future projects.
Dan Foley is president and owner of Foley Mechanical, Inc. based in Lorton, VA (www.foleymechanical.com). FMI specializes in radiant, hydronic and steam systems as well as mechanical systems for large custom homes. He can be reached at 703-339-8030 or at email@example.com.