Carel k.Air, User Manual, Page: 90 / 192

90
Functions
k.air +030220981 rel. 1.2 - 01.12.2020
Condition for entering defrost mode
The unit starts defrosting when the following condition occurs:
• Outside temperature < Bypass damper maximum opening threshold (default = 5°C);
• Exhaust temperature < Exhaust temperature threshold
End defrost conditions
The unit ends the defrosting procedure if one of these conditions occurs:
• Exhaust temperature > Exhaust temperature threshold, or
• The “Maximum defrost duration” time has elapsed from when defrost mode starts.
Note:
when the outside temperature is very low, and the minimum time has elapsed between successive defrosts, defrosting
starts again.
OFF
ON
Byp_Damp_Max_Op_thr
Ext_T_thr
Rec_exch_def
t
t
t
Ext_T
Ext_T
T_ON T_OFF T_ON
30220980_207_R01
Key
Exh_T Exhaust temperature
Ext_T Outside temperature
Byp_ Damp_
Max_ Op_thr Start defrost threshold
Exh_T_thr End defrost threshold
Rec_exch_def Heat recovery unit defrost
T_ON Maximum defrost duration
T_OFF Minimum time between defrosts
t time
Fig. 9.ay
R if D escription D ev Min Max UoM D ir Modbus BAC net
CO M PR E SSOR
Ua09 Evaporator defrost start threshold -1.0 -10.0 5.0 °C R/W HR1526 AV3027
Evaporator defrost end threshold 50.0 DfrStart-
Thrsh 99.9 °C R/W HR1527 AV3028
Ua12 Defrost delta bypass damper 3.0 0.0 10.0 K R/W HR1528 AV3029
Evaporator defrost start delay time 5 0 65535 min R/W HR1529 PIV3030
Ua15 Enable refrigerant ciruit for active heat recovery unit - 0 1 - R DI705 BV1163
Defrost time for stop compressor 5 0 65535 min R/W HR1530 PIV3031
Ua18 Defrost minimum time 1 0 65535 min R/W HR1531 PIV3032
Defrost maximum time 5 0 65535 min R/W HR1532 PIV3033
Time between two defrost 30 0 65535 min R/W HR1533 PIV3034
Ua21 Defrost dripping time 90 0 9999 s R/W HR1534 PIV3035
Post-dripping time [s] 30 0 9999 s R/W HR1535 PIV3036
Ua24 BLDC minimum speed in defrost 40.0 -999.9 999.9 - R/W HR1536 AV3037
Reverse valve delta P 3.0 0.0 5.0 bar R/W HR1537 AV3038
Ua27 Defrost: delay time before change over 20 0 900 s R/W HR1538 PIV3039
Defrost: delay time after change over 10 0 900 s R/W HR1539 PIV3040
Ua30 Fans request during evaporator defrost 3 0 3 % R/W HR1540 PIV3041
Fans request during evaporator defrost 30.0 0.0 100.0 % R/W HR1541 AV3042
Fans request during evaporator defrost 0 0 100 % R/W HR1542 PIV3043
Fans request during evaporator defrost: dripping
2 0 3 % R/W HR1543 PIV3044
Fans request during evaporator defrost: dripping
30.0 0.0 100.0 % R/W HR1544 AV3045
Fans request during evaporator defrost: dripping
100 0 100 % R/W HR1545 PIV3046
Fans request during evaporator defrost: post dripping
2 0 3 % R/W HR1546 PIV3047
Fans request during evaporator defrost: post dripping
30.0 0.0 100.0 % R/W HR1547 AV3048
Fans request during evaporator defrost: post dripping
100 0 100 % R/W HR1548 PIV3049
Ua33 Disable Low supply temperature alarm TRUE 0 1 - R/W CS250 BV250
Tab. 9.bf