Commercial Products  >  Draft Control
BDC 26
Redundancy Controller

The BDC 26 Redundancy Controller is used when an option to operate a redundant mechanical draft system is required. It allows the safeties to be bypassed in case of an EBC 30/31/35 failure. Typical uses are: Controlling redundant mechanical draft systems serving boilers and water heaters in hospitals, hotels and other applications where possible downtime during repair, maintenance or system failure is not acceptable.

The BDC 26 serves as a controlling link between two EBC 30/31/35 Modulating Draft Controllers each controlling a mechanical draft fan and a variable frquency drive.

One EBC 30/31/35 with VFD(s), sensors and the mechanical draft fan(s) is considered the “Primary System” and the other EBC 30/31/35 with VFD(s), sensors and mechanical draft fan(s) is considered the “Secondary System”.

For true redundancy, the Primary and Secondary System’s power supply should be from indpendant electrical circuits, but alternatively, they can be supplied by the same source if needed. In addition, it is also recommended that each VFD is powered by its own electrical circuit if possible.


  • Panel-mounted - NEMA1
  • Switch Operation of Primary Power Venter to the Secondary in an alarm and/or time-out event.
  • Operate one of two Power Venters independent of each other based on boiler demand.
  • Allow operator to manually switch between the Primary and Secondary Power Venters when no alarms are present.
  • Go into ‘Alarm State’ with visual and auditory annuciation if an alarm condition is present on either the primary or secondary unit.
  • Manual pushbutton reset of ‘Alarm State’ Hardware:

This controller can be used in conjunction with ENERVEX draft control systems such as the EBC30 and EBC31. It can also integrate with most ENERVEX fan models including RSV, TDF, and IPVB.


Power Supply 1x120VAC
Max Current 10 Amps
Operating Temperature 15 to 140°F (-10 to 60°C)
Analog Inputs 4
Water Temp Sensors (2) NTC 32 to 302°F (0-150°C)
Flue Temp Sensors (2) PT1000 -58 to 662°F (-50 to 350°C)
Analog Output (2) 0-10 VDC Modulating
Digital Outputs (4) 250 VAC
Warranty 2-year Factory Warranty
Listing/Certification UL 508A Standard for Industrial Control Panels
CSA-22.2 No. 14 "Industrial Control Equipment"