Linkageless Control Technology Provides a Breakthrough in Efficiency and Ease of Operation

Preferred’s FlexFit offers a smart, less expensive retrofit solution for boiler room controls.

DANBURY, Conn., Aug. 29, 2023 /PRNewswire-PRWeb/ — High costs, inefficient heating, unreliable operation, and myriad other headaches can plague the boiler room. In an effort to make boiler operation less expensive and more dependable, many operations professionals are switching to “linkageless” control systems, which utilize individual servos on burners to control fuel and air ratios, in turn providing more savings to the end user.

“This is a control solution that delivers benefits for all members of an operations team,” said David Bohn, President and CEO of Preferred Utilities.

The FlexFit controller brings linkageless control with an integrated flame safeguard system. This is a retrofit solution that increases savings and efficiency, while also improving control in the boiler room.

The FlexFit flame safeguard plugs directly into the Fireye E110 or Honeywell RM7800L wiring bases, eliminating extensive re-wiring. Retrofitting a burner with a FlexFit provides advanced features such as oxygen trim for fuel savings and safety, FD Fan variable speed drive (VSD) control for electrical savings, draft control for better combustion control, and high flue temperature lockout to prevent boiler damage. Linkageless control also provides wider burner turndown that reduces start stop cycling, purges heat losses, and prevents burner corrosion.

Some of the biggest benefits of linkageless systems include:

  • Higher efficiency: O2 levels may fluctuate due to seasonal changes, but they will always return to the O2 value for the highest fuel and electrical efficiency. In addition, turndown is often improved resulting in less cycling of the burner.
  • Monitoring and communication: The system communicates via Modbus and reports on all functions. The main module monitors the positions of all fuel- and air-control devices. Any positioning error shuts the burner down safely.
  • Automatic adjustments for ambient air and fuel changes: Linkage systems can cause major problems for technicians. Once all the linkage is set, the ambient air density may change, throwing the system off. With O2 monitoring, the system will automatically adjust to provide the proper O2 value for that firing rate. In addition, instead of system readjustment every time there is a fuel switch, the positions of all servos are programmed and independent. This means that the system adjusts automatically to fuel/air ratio changes as well as fuel changes.

The FlexFit system is an innovation in linkageless technology. Leveraging the industry-leading BMU (Burner Mate Universal) platform, the FlexFit can be used in new installations or easily retrofitted into existing jackshaft control panels that use supported common flame safeguards. A trained technician can drop in and install the FlexFit retrofit in as little as one day, making the FlexFit installation a fraction of the time and cost of other linkageless systems with the same control benefits.

Additional fuel savings are accomplished with linkageless combustion control by utilizing the optional oxygen trim. Electricity savings are provided by the ability to control a Variable Speed Drive for the FD Fan. In addition to flame safeguard and combustion control, the FlexFit also includes optional draft control.

The FlexFit communicates to Building Automation Systems by Modbus or optional Ethernet. And because it is microprocessor-based and pre-engineered, the FlexFit is an economical alternative to more expensive PLC-based boiler controllers. The parts are in stock for immediate delivery and require no programming.

All three FlexFit models are compatible with Preferred’s model QA annunciator. The QA5004-FF adds expanded lockout and diagnostic information to the FlexFit’s repertoire of user-friendly features. The new messages are automatically reported from the QA to the FlexFit display and are recorded in the FlexFit’s time/date-stamped alarm history.

“This is a control solution that delivers benefits for all members of an operations team,” said David Bohn, President and CEO of Preferred Utilities. “Owners will see savings through electrical and fuel efficiency, and they’ll have tighter control of boiler room functions. Managers will be able to get ahead of emergencies before they happen, and technicians will appreciate the easy installation, in-and-out maintenance, and local support.”

With a flexible design that is more affordable, more accessible, and more accurate, FlexFit is one of the most efficient retrofit solutions available. For more information or to get a quote, visit

About Preferred Utilities Manufacturing.

Founded in 1920, Preferred Utilities Manufacturing Corporation is an engineering-based manufacturer of fuel oil handling systems, boiler instrumentation and controllers, high quality burners, nuclear power plant outage reduction tools, and related component parts for commercial, institutional, and industrial facilities. Preferred applies continuous research and development to existing products, helping them to lead the industry with new and innovative power plant solutions. Their manufacturing, engineering, and administrative headquarters is located in Danbury, Connecticut, with regional sales and service offices throughout the United States.

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