Draft Controls Are Still a Critical Part of Modern Boiler Operation

New updates to our draft controllers, including the popular JC-22 model, make it an even more effective solution.

Draft controls have long been an important component in boiler systems to help control negative pressure. Even though modern forced draft boilers are usually airtight, they still often need draft controls to help stabilize burners using flue gas recirculation for NOx control. If the stack draft is too negative, the forced draft fan will not be able to induce enough flue gas to meet the required NOx emissions. And if the stack draft is not repeatable, the fan will induce varying amounts of flue gas recirculation that will make the fuel air ratio control unstable. The combustion controller can’t precisely control the air flow through the burner if the boiler draft is constantly changing, so effective draft controls are critical.

Preferred’s JC-22D2 Draft Monitor and Controller is a microprocessor based draft controller, indicating instrument, and alarm monitor. It incorporates advanced control algorithms for tall stacks, multiple furnace stacks, and fast varying loads. Additional features include:

  • Automatic Draft Control
  • Precision Outlet Draft Control
  • Firing Rate Feedforward
  • Floating Draft Control
  • PID Draft Control
  • Automatic Damper Sequencing
  • Damper Adjustable Start Position
  • High Draft Alarm
  • Modbus Communication with RS-485 and Ethernet capability.
  • Live Data Tuning Screen

To meet the increasingly demanding requirements of modern low NOx burners, Preferred has updated the JC-22 draft control to be an even more sophisticated solution. Brand new updates include:

  • Modbus TCP/IP ethernet communications.
  • Color touchscreen, similar to the PCC-IV.
  • Controller depth is 4.88” for shallow panel mounting. Compare to 7” depth on the JC-22D.
  • Plug-in wiring terminals for quick controller replacement.
  • Firmware updating in the field via JCD2_Edit and USB port.
  • Up to 50 historical alarm and event messages with time/date.

The JC-22 product is designed to correct for a full range of boiler issues. It will control draft resulting from changes in ambient air temperature, changes in stack temperature, changes in wind velocity blowing across the stack, and variations in draft conditions caused by multiple boilers connected to a common breeching. The sensitivity of low NOx burners has increased the need for draft controls, and the JC-22 is a versatile and efficient solution.

Preferred was one of the earliest providers of boiler draft controls, and we continue to design and manufacture the most advanced draft control products available to handle any draft control application. View our complete Draft Controller Product Line or contact us today to learn more about how recent advances in the JC-22 Draft Monitor and Controller can help maximize the effectiveness of your boiler system.

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