Call it a smart pump, intelligent pump or high efficiency pump. These variable-speed circulation pumps, often with electrically commuted motors and integrated controls, promise energy efficiency and flexibility not found in the traditional fixed-speed pump. How do they work and what advantages do they offer?

This month we talked “smart pumps” with manufacturers of these sophisticated systems. Sharing their know-how are: Kirk Vigil, business development manager, Grundfos Pumps Corporation; Mark Chaffee, marketing vice president, Taco, Inc., and Brent Ross, director – configured and standard building products, Armstrong Fluid Technology.

Reeves Journal: Can we talk about what makes a “smart” or high efficiency pump smart? What are the components of these units?

Grundfos Pumps Corp.: There are two primary components that distinguish “smart” or high energy- efficient pumps from traditional single and three-speed pumps. First is the use of an ECM, or electrically commuted motor, a.k.a. permanent magnet motor versus standard induction/asynchronous motors. ECM motors are compact and powerful. ECM motor construction and efficiency alone can provide 50% energy consumption reductions. Second, incorporating speed control within the pump, variable speed pumping, allows the pump to be sped up or slowed down based on the environment it is operating in.

Degrees of “smart” can be debated; however, at Grundfos we use advanced software, AUTOADAPT, within microprocessors in the pump control head. AUTOADAPT uses internal sensors and advanced algorithms to monitor the actual and dynamic changes in the system and continually control the pump speed to satisfy the system demand.

Taco, Inc.: The hearts of Taco’s Viridian wet rotor “smart” pumps are the ECM or electronically commutated permanent magnet motors. The pumps include an internal circuit board to drive the motor and serve as the “brain” so that it responds to system variables (i.e. pressure or temperature) predictably, while saving electrical energy and optimizing system performance. 

SA Armstrong: The first ingredient is that it reacts to the system by slowing down or speeding up. It’s actually amazing technology the way it does it; it’s able to do the equivalent of sensing the need for more or less heat in a zone or radiator component. It does it through change in pressure and therefore, the product automatically reacts to changes in the system. That’s what makes the smart pump different.

In addition, more sophisticated smart pumps actually learn the system. These pumps incorporate an “auto” function which learns the characteristics of a specific system and adjusts its controls to fit these characteristics Not only do they react, but over time, they produce the best control formula for that system and actually learn what the system is about and is able to better control it. 

Most common is by sensing the reduced need of heat in a zone or radiator component through change in pressure. Other means can be a signal from a controller as boilers now have or direct sensing of temperature.

RJ: What are the advantages of a high–efficiency variable speed pump over a controlled or fixed- speed pump?

Grundfos: The advantage you will hear and read the most about is reduction in energy consumption. This is realized in operating cost due to lower utility bills. However, the biggest or best advantage for using high-efficiency variable speed pumps and circulators is comfort. When matched with an intelligent control, these pumps can provide just the right amount of flow to satisfy a system demand, or need for heating or cooling.

Fixed-speed pumps by definition run at one speed, full on. So, unless the system otherwise controls media temperatures, this can have the same effect as uncontrolled forced air systems. Occupants may feel the swing in temperatures during system cycles. Variable speed pumps controlled correctly can even out those cycles and provide constant, uninterrupted comfort.

Taco: Versatility of operation is one of their intelligent strengths.  There’s very little that can’t be done with a Viridian pump, making them a pretty smart choice.  For instance, Viridian offers several variable speed pre-set options to match the job, including:  differential temperature (delta-T), constant and proportional differential pressure (delta-P), infinitely variable speed, set point heat or cool, boiler protection, or external control via a building management system.  On the commercial-sized Viridian pumps, built-in, web-enabled access and the ability to change settings remotely make installation, monitoring and service easy.

SA Armstrong: The first advantage is lower energy consumption. Smart pumps typically achieve 50 to 80 percent energy savings. There are a number of things that go into that over and above the control aspect. The second advantage: One size fits all. An installer can stock one, two or three smart pump models, like those in our Compass and Design Envelope lines, instead five to 15 traditional models. Those with an “auto” adjustment function, of course have the circulator adjust automatically to the system, instead of an expensive callback to set another control parameter, which does reduce expensive callbacks.

RJ: Do these pumps have a longer service life than fixed-speed units? What about maintenance?

Grundfos: Typically, high-efficiency pumps and circulators with ECM motors have longer life expectancy than induction motor circulators. There is less wasted energy do to motor design, and most manufactures and upgraded the quality of components in these pumps making them for robust and durable. Maintenance may vary between manufacturers and models. Speaking for Grundfos, and specifically high-energy efficient wet rotor circulators, they are virtually maintenance free.

There are growing concerns about these high-energy efficient pumps and their ECM motors with powerful magnets creating issues by attracting additional iron oxide, or magnetite. Iron oxide and magnetite form a black sludge in hydronic heating systems.

Again, speaking for Grundfos, the overall design in our wet rotor circulators ensures superior resistance to impurities such as magnetite. Resistant materials, coatings and flow designs minimize particles in our rotor cans. It is a clear design criterion for Grundfos that all our circulators must withstand high levels of iron oxide and magnetite.

Taco: Taco’s smart pumps are built with the expectation that will not require, or need to receive routine maintenance.  They have no couplers or seals and the water they circulate is also their coolant, so that’s an advantage.  But it can also be the source of challenge:  system water quality is important not only for efficient system operation, but also for trouble-free pump operation. The cleaner the water, the better to maintain trouble-free operation.  

Armstrong: It’s still early to tell; this is a newer technology. Due to the lower speed, and therefore less wear and tear, we think they will. With an intelligent pump, the “soft start” and ability to throttle down and not run all the time at full capacity greatly reduce not only energy use but also the wear and tear, extending the life of the pump and  the entire system into which it is integrated. For maintenance, the European-style wet product has virtually no maintenance.

RJ: What about fuel costs versus traditional fixed-speed pumps? What’s the typical ROI?

Grundfos: Fuel cost savings vary from system to system due to design complexity and system size. Generalizing, we state that users can experience up to 85 percent electrical energy savings and up to 50 percent in fuel savings. We have seen case studies and field tests lower and higher than these percentages. We have also seen return on investments anywhere from a few months to three years. There are too many variables to state a “typical” ROI.

Taco: ECM-driven pumps offer up to an 85 percent decrease in electrical consumption compared to standard pumps of the same size, so that’s a big step in the right direction. ROI also depends on the cost of electrical energy, the mode of operation chosen and how oversized the current pump is; usually the larger the pump and the higher the cost of electricity, the greater the ROI.  It’s also important to recognize that the pump is part of a system, if operated in the right mode it can also save on system wear and tear or fuel, by helping the boiler run more efficiently, which can add up to hundreds of dollars in additional savings.

Armstrong: The smart pumps are two to three times the cost of traditional product although costs will come down in the future. Payback is typically between three and 10 years from the pump energy, which is often not a viable investment unless the individual is motivated to save the environment. The circ control can enhance the operation of the boiler, and if it does that, the savings can be 10 times the energy savings of the pump.

RJ: What kind of projects call for a “smart” pump?

Grundfos: Variable–speed pumps with intelligent control should be used in any system that has changing or challenging environmental conditions. Any system that must adjust or adapt to dynamic environmental changes is suited for these pumps. These pumps are ideal for systems with multiple zones or systems with a variety of delivery appliances.

SA Armstrong: A circulator pump, traditional or smart, is generally used in residential plumbing and heating systems. You’d want to consider the smart pump for projects in areas where you have expensive energy; Hawaii and New York City come to mind where power costs are very high. Obviously, smart pumps figure into replacement/retrofit projects, because you need to stock fewer units on the truck, and also the contractor has the opportunity to up-sell the homeowner around energy efficiency. Smart pumps tend to work better in systems that have modulating valves. In larger products more than one horsepower and commercial projects, the smart pumps are viable universally. On the residential side, the applicability is more limited. 

"This article was originally posted on ww.reevesjournal.com."