Heating operation - 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

Heating stages are controlled by the W1 through W3 thermostat inputs.

  • A W1 input energizes the H1 output.
  • A W2 input energizes the H2 output.
  • A W3 input energizes the H3 output.

When the ignition safety verification process is complete, the ignition module energizes the gas valve and provides a 24 V input to the MV terminal on the UCB. This does not apply to units with electric heat.

The FAN ON HEAT DELAY timer starts as soon as 24 V is present on the MV terminal. When the timer expires, the FAN output for the indoor fan operation energizes.

Note: On units with electric heat, FAN ON HEAT DELAY must be set to 0.

When the thermostat heat inputs are lost and the 120-second Minimum Heat Run Timers have expired, heating outputs stage off. The Fan Off Heat Delay timer starts when all heating outputs are off. When the timer expires, the FAN output for the indoor fan operation de-energizes.

Note: If 24 VAC is present on W2 without W1, H1 energizes immediately and H2 energize after a 30-second interstage delay. If 24 VAC is present on a W3 without W1 and W2, H1 energizes immediately and H2 energizes after a 30-second interstage delay.
Note: Heat pumps have unique heating logic. See Heat pump.