Limit - Johnson Controls - LIT-12011950 - Building automation software - Smart Equipment Controller - 5.0

Smart Equipment Controls Sequence of Operation Technical Bulletin

Brand
Johnson Controls
Product name
Smart Equipment Controller
Document type
Technical Bulletin
Document number
LIT-12011950
Version
5.0
Revision date
2024-06-06
Product status
Active
Language
English

Setpoints and related data

  • Heat limit switch lockout (LimitLO)
  • Heat limit 2 switch lockout (Lim2LO)
  • Heat limit 3 switch lockout (Lim3LO)
  • Reset lockouts (ResetLO)

Inputs

The input for limit is 24VAC monitoring at the limit input on the UCB (Limit, Lim2, Lim3).

Outputs

The output for limit is the output relay for fan and heat stages.

Operation

When the UCB senses 0 VAC at the limit switch input, it energizes the indoor blower relay and it performs the fan delay off when the limit returns to normal and senses 24 VAC.

If the limit trips while in a fan minimum off time, the UCB immediately energizes the indoor blower relay ignoring the fan minimum off time.

The UCB logs the first incident and tracks the runtime. If the limit switch opens three times within one hour of run time, it flags an alarm and lock on the indoor blower relay and disables heating.

Note: To manually reset the lockout condition, navigate to the ResetLO point in the user interface and change the value from no to yes.