Smart circulators propel radiant systems into the future

Efficient HVAC systems, such as those that rely on radiant heating and cooling distribution, are already on the forefront of net zero design — buildings that generate as much energy annually as they consume.

According to a study, Zero Net Energy Buildings, by the Continental Automated Buildings Association (CABA) and new buildings institute (nbi), 64 percent of the buildings used radiant systems. The study cited HVAC system design as a critical factor in achieving net zero energy targets, along with envelope design and building siting.

Highly efficient and technologically advanced components of HVAC systems, such as circulator pumps, do not by themselves make a radiant system efficient. Each component must be designed, installed and operated in a complete system in order to realize goals related to energy consumption. In the case of circulators, that means the circulator will be operating at higher levels of efficiency over a broader range of operating conditions as well as adjusting speed to react to system changes.

There are a number of new technologies related to circulators as well as impending regulations that make these little engines of radiant systems of interest in 2017 and beyond.

Conservation standards

The most efficient circulators on the market feature electrically commutated motors (ECM), but if regulations under consideration by the Department of Energy become law as expected by the end of 2017, all circulators in commerce in 2022 will be required to include this technology.

Late last year, the Appliance Federal Rulemaking Advisory Committee (ASRAC) working group made up of Hydraulic Institute members and pump manufacturer representatives, including representatives of Xylem Inc., presented to the ASRAC and the secretary of energy terms for the development of a test procedure and energy conservation standard levels for circulator pumps. A notice of proposed rulemaking will be issued prior to the final rule, followed by a four-year compliance period during which manufacturers can upgrade circulators to meet the new standards or retire inefficient products.

This new wave of ECM circulators has already begun replacing circulators with induction motors in the marketplace, as permanent magnet motors are the technology of choice for higher efficiency — helping to boost system performance by up to 85 percent. The permanent magnet in the motor results in fewer friction losses in the pump compared to traditional AC motors.

The ability of ECM circulators to run at variable speed in order to adjust to system demand is another key energy-saving feature. Circulators operating at different speeds provide greater system control and flexibility compared to constant-speed circulators.

Other advantages with newer ECM circulators include quicker start up in a system, which can be as simple as six to eight button pushes with some models. In addition, an easy-to-read interface displays key indicators, such as flow rate, head, speed and power consumption.

Smart components

With more control modes and intelligence on the circulators themselves, system operators can find out what the circulator is doing any minute of the day or night, and they don’t have to be on site to monitor the system. The advanced analytics generated by integrated drives with sensorless technology incorporate algorithms that enable the circulator to monitor its power requirements and automatically adjust to meet system requirements.

Smart technology and greater connectivity through IoT is dramatically rising around the globe. According to information technology research company Gartner Inc., by 2018 the use of connected things in commercial and residential buildings will top 2 billion, compared to 5.5 million in 2015.

Larger circulators are incorporating open protocols like BACnet, enabling them to be linked to a building management system (BMS) to increase communication with other building systems. Instead of monitoring only individual functions, as suggested above, data from circulators can be connected to lighting controls to adjust HVAC and lighting systems. Taking that a step further, IoT enables predictive control, in which BMS data is linked with online weather forecasts and building usage patterns to even further refine HVAC and lighting systems needs on a given day. As a result, building occupants are more comfortable and energy use is optimized.

As these trends of integration, wireless technology and adaptive controls continue to emerge, there is a learning curve on the path to integration and optimization. In the 2015 CABA/nbi study, 82 percent of the designers agreed or strongly agreed that control communication platforms and protocols among systems need improvement, and all study participants (designers, operators and occupants) ranked building control strategies “very important” or “critical” to net zero energy success.

Awareness of new technologies and education also will play a vital role in ensuring new technologies are maximized and sustainability goals achieved.

Jack Kang is Product Line Manager for Circulators and Centrifugal Pumps at Xylem Applied Water Systems.