External Backup Heater Control - Daikin ALTHERMA HT Service Manual

ESIE09-08B
7.5

External Backup Heater Control

Normal operation
NORMAL OPERATION
(BUH assistance)
Step 0 -> Step 1
&
Step 1 / 2 -> Step 0
or
Step 1 -> Step 0
Step 1 -> Step 2
&
Step 2 -> Step 1
or
Step 0 -> Step 2
&
(*): approximate value (depends on operation conditions (e.g. dT, HP indoor unit))
Appendix
Step 0
(no BUH operation)
TM
TM TM
1 1 2
Step 1
TM
2
Step 2
 20 minutes compressor operation
 Compressor runs on high frequency
 Pump speed > ~2500 rpm (with E-03 set to default 1)
 LWT > ~ LWT setpoint - 8 (*)
 LWT < ~ LWT setpoint - 4 (*)
 If controller room thermostat function: RT<RT setpoint - 2 (normal heat load)
 Q2L = OFF
 DHW operation
 LWT > LWT setpoint + 2
 If room thermostat function: RT > RT setpoint
 LWT > LWT setpoint
 TM2 up
 LWT < ~ LWT setpoint - 6 (*)
 RWT < ~ LWT setpoint - 10 (*)
 LWT > ~ LWT setpoint - 2,5 (*)
 RWT > ~ LWT setpoint - 6 (*)
 20 minutes compressor operation
 Compressor runs on high frequency
 Pump speed > ~2500 rpm (with E-03 set to default 1)
 LWT < ~ LWT setpoint - 8 (*)
Note
 Timer during normal operation
The TM* indicate timers, these start counting down if they
are crossed when going from one step over to another
step.
TM1: 5 minutes
TM2: 10 minutes
 BUH operation after defrost if already active before
Timer: 10 minutes
Compressor operation: 5 minutes & high frequency
External Backup Heater Kit
251