Independent Circuit Defrost Operation - Trane ReliaTel Diagnostic Manual

Table 37. Demand Defrost Fault Designation
Symptom
Coil temperature Sensor Failure
Outdoor Temperature Sensor Failure
D is below Minimum Value 12 minutes after defrost is
T
terminated
Defrost Terminated on time requirement
D is above Maximum Value 12 minutes after defrost is
T
terminated
D does not change by 2 degrees in an hour's time
T
starting 12 minutes after defrost is terminated and D
less than or equal to 4 degrees 12 minutes after defrost
is terminated
Defrost Termination Temperature (DTT) = Outdoor Air Temperature (OAT) + 47ºF
57ºF <= DDT <= 72ºF
DT = Outdoor Air Temperature (OAT) – Outdoor Coil Temperature (OCT)
Defrost Initiate Temperature= 1.8 * (DT) 12 Minutes After Defrost Mode is terminated)

Independent Circuit Defrost Operation

For Odyssey and EMEIA Independent Circuit Heat Pump units with two outdoor coil temperature
sensors, the unit will perform defrost per circuit based on its own coil temperature sensor value,
the outdoor ambient temperature, and the accumulated circuit run time. At least one stage of
auxiliary heat will be energized anytime either circuit is in defrost mode. All other defrost
functionality, including the diagnostic conditions, will perform as described above independently
per circuit.
RT-SVD03G-EN
Diagnostic
Sensor is shorted or open Activate Defrost Fault
Sensor is shorted or open Activate Defrost Fault
Low D
T
Time Termination
High D
T
is
T
Unchanging D
T
Heat Pump Demand Defrost
Response
If> 2 hours, activate Defrost Fault Reset timer if D
returns within bounds.
If defrost is terminated on time requirement (vs.
differential temperature) After 10 consecutive Time
Terminations, activate Defrost Fault.
Initiate Defrost
After 16 consecutive High D
T
Defrost Fault.
Initiate Defrost and activate Defrost Activate Defrost
Fault
T
Initiations activate
95