TECH TOPIC: High Efficiency Pumps
September 6, 2012
Today's circulators aren't anything like the units your granddaddy used to install. They may look similar, but today's high-efficiency pumps typically feature advanced control systems.
One of the most common is Electronically Commutated Motor technology. Long a mainstay on the HVAC and commercial refrigeration side of the house, ECM-controlled motors are able to automatically match their output to system demand. Since the pump's flow is automatically matched to the system demand, the other components in the system aren't subjected to things like excessively turbulent flow which can encourage erosion and failure. Also, pump noise is kept to the bare minimum as well since it only needs to run as fast as the system is demanding.
As a result, you have another factor that may be moving circulator technology toward ECM technology. These circulators can save up to 80 percent of the wattage normally used by a constant speed pump or a pump that varies its speed in three or four definite "steps" between off and wide-open throttle.
Another large benefit to consider when choosing circulators is ECM-controlled units' often slower speeds makes for easier life for the bearings-extending the service life of the units and reducing maintenance costs.
The Wilo-Stratos GIGA is the newest EC-controlled pump. It's a new glanded pump that uses ECM technology to rack up impressive 94 percent efficiency levels thanks to its high efficiency drive.
"These are ECM pumps with a fully integrated control system," said Mark Dagostino, president of Wilo USA. "It is an ECM high-efficiency circulator for closed loop applications addressing duty points up to 160 feet of head and 200 gpm of flow. This is the newest addition to our existing line of Stratos ECO, Stratos, Stratos D and Stratos Z ECM circulators."
At Grundfos, the newest offering the Alpha, which features AUTODAPT performance-a factory setting which tells the pump to automatically analyze the heating system and adjust its performance accordingly: "The Alpha is a high-efficiency ECM motor platform, said senior product specialist Bob Reinmund. "It is our product offering at the moment. However, as always with Grundfos, we're always striving to improve our product every day. You will see improvements in the Alpha as we move down the road that's for sure."
What's all this "ECM" jazz, anyhow, and how does it make the motor driving the pump so bloody efficient? The answer to that question is everyone's favorite: Science!
"Its' magnetized rotor design in inherently more energy efficient than a comparable asynchronous motor," Dagostino said. "Couple an ECM motor with a variable speed drive, integrated control system and you get an extraordinary reduction in consumed energy for operation. It operates much like cruise control does for a car."
Let's say we have an ECM motor and we're going to do a head-to-head test against a comparable induction/asynchronous motor. Fundamentally they both have the same stator principle functionality. The huge difference between the two motor types is in the rotor. In an ECM motor, the rotor is permanently magnetized. Half is positive and half is negative. That gives the rotor its polarity and opposite polarities chase each other. In the induction motor the rotor isn't magnetized. It's a dumb piece of metal.
"Fundamentally that's the core difference between the two. Where it gets exciting is, in the induction motor you've got to apply power to the stator and the rotor. With an ECM motor, you only have to apply power to the stator,' Reinmund said. "In effect, if you're energizing half the motor components you save roughly 50 percent on the power over a comparable standard unit. Let's say you have a 1/2 hp induction motor that needs 1,000 watts. The ECM motor will still generate 1/2 hp, but only consumes 500 watts. It really doesn't matter who makes the motor. That's an inherent design feature with an ECM motor."
Because ECM pumps are relatively new on the plumbing front there are a few misconceptions about them. Probably because of the whole idea these pumps are "computerized," there's a perception floating around out there ECM pumps are difficult to program and/or set up. Yeah. Well, no.
"Some in our industry think HE pumps are complicated to set up and program, thinking they are like VFD's (variable frequency drives) that have been used for years to control pumps," Dagostino said. "The opposite is the case with Wilo ECM HE pumps. All programming features can be manipulated simply by using our "Red Button" technology. That is ONE simple knob can access AND change all data within the pumps operating system."
Reinmund said some of the nomenclature used by the industry is, "used a little loosely."
"Someone hears the term, 'High Efficiency', so you might think 'variable speed' in conjunction with ECM," Reinmund said. "If the guys are familiar with variable speed pumps, you have to go to a keypad and enter a bunch of setpoints for that particular application. There's a long menu of stuff to enter in and it can be very complicated. With this type of technology in circulators, at least as far as what Grundfos is offering, there is no programming required. It's pretty much plug-and play."
Another misperception is one that's been mentioned already. ECM technology, at least in the North American plumbing contractors' universe, is considered "new technology." That's not the case by a long shot.
"ECM motors have been around for several decades and we've had an Alpha-type platform approaching 13 years," Reinmund said. "It's not new technology to some manufacturers, it's just new technology to the industry. I don't think you can get a piece of commercial refrigeration equipment that doesn't have an ECM motor on it. That industry has totally embraced ECM technology."
So this brings up the question as to what will it take to make ECM technology as commonplace and well-understood in the plumbing business as they are on the commercial refrigeration market?
"There is talk and there are committees forming-Radiant Professionals Alliance, IAPMO, Hydraulic Institute-to start addressing how to classify circulators and, ultimately, efficiency levels, Reinmund said: "The Europeans have taken it to the extent that asynchronous motors in fractional horsepower ratings will be extinct come 2013. You will not be able to purchase one over there. To me the pain threshold seems to be about 17 cents a kilowatt. That's when people start looking around to see what they can do to save energy. At 20 cents a kilowatt, they're ready to start making changes to the inefficiencies in their boiler rooms."