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How to set the OTHER HEATING SOURCE
To set the OTHER HEATING SOURCE, go to MENU> FOR 
SERVICEMAN> OTHER HEATING SOURCE, Press OK. 
The following page will appear:
If backup heater is available, please select YES at BACKUP 
HEATER. Press OK and the following page is displayed:
If an additional heating source is available, please select YES at 
the corresponding position. Press OK and the following page is 
displayed:
When the cursor is on HEAT MODE or DHW MODE, Use ◄ ► to 
select YES or NON. If YES is selected, the backup heater will be 
available in the corresponding mode, otherwise it will be unavailable.
When the cursor is on T4_IBH_ON dT1_IBH_ON t_IBH_DELAY
or t_IBH12_DELAY, Use ◄ ► and ▼ ▲ to scroll and adjust the 
parameter.
When the cursor is on HEAT MODE or DHW MODE, Use ◄► to 
select YES or NON. If YES is selected, the additional heating source 
will be available in the corresponding mode, otherwise it will be 
unavailable.
NOTE: If YES is selected in DHW MODE, the installation of an 
additional heating source should follow “8.5 Application 5/Applica-
-tion b”
When the cursor is on T4_AHS_ON dT1_AHS_ON dT1_AHS_
OFF or t_AHS_DELAY, Use ◄ ► and ▼ ▲ to scroll and adjust the 
parameter.
T4_AHS_ON is the ambient temperature for starting the additional 
heating source. When the ambient temperature rises above T4_AHS_
ON, the additional heating source will be unavailable. The relationship 
between the operation of additional heating source and ambient 
temperature is shown in the picture below:
T4_IBH_ON is the ambient temperature for starting the backup 
heater. If the ambient temperature rises above T4_IBH_ON, the 
backup heater will be unavailable. The relationship between operation 
of the backup heater and the ambient is shown in the picture below.
dT1_IBH_ON is the temperature difference between T1S and T1 for 
starting the backup heater. Only when at the T1<T1S-dT1_IBH_ON 
can the backup heater turn on. When a second backup heater 
is installed, if the temperature difference between T1S and T1 is 
larger than dT1_IBH_ON+2, the second backup heater will turn on. 
The relationship between operation of the backup heater and the 
temperature difference is shown in the diagram below.
dT1_AHS_ON is the temperature difference between T1S and T1B for 
turning the additional heating source on(only when T1B<T1S-dT1_AHS
_ON will the unit turn on)  dT1_AHS_OFF is the temperature difference 
between T1S and T1B  for turning the additional heating source off (
when T1B≥T1S+dT1_AHS_OFF the additional heating source will turn 
off), t_AHS_DELAY is the time that the compressor has  run before 
starting the additional heating source. It should be shorter than the 
additional heating source start time interval.The operation of the heat 
pump and the additional heating source is shown below:
t_IBH_DELAY is the time that the compressor has run before the 
first backup heater turns on (if T1<T1S).
t_IBH12_DELAY is the time that the first backup heater has run 
before the second backup heater turns on.
YES
YES
NON
NON
YES
YES
NON
NON
YES
YES
NON
NON
YES NON
T1s-T1 T4<T4_IBH_ON
OFF
OFF
OFF
ON
OFF
OFF
ON
ON ON
ON
OFF
T4
T4HMIN
T4HMAX
Heat mode
by heat pump
T4_IBH_ON
Heat mode
by IBH only
Heat mode by heat 
pump and IBH
T1S-dT1_IBH_ON
IBH1 OFF
IBH1 ON
T1
T1S-dT1_IBH_ON-2
IBH2 OFF
IBH2 ON
T1
OFF T4
T4HMIN
T4HMAX
Heat mode
by heat pump
T4_AHS_ON
Heat mode
by AHS only
Heat mode by heat 
pump and AHS
If solar energy kit is installed, please select YES at “7.3 SOLAR ENERGY”, 
then the solar pump will operate when the solar energy kit operating for 
domestic hot water heating, and the heat pump will stop operating for 
domestic hot water heating.