Service Manual

Table Of Contents
Auxiliary heater control by outdoor temperature 1
This control selects heat pump or external heater according to the outdoor temperature. When out-
door temperature is high, the heating is performed by using heat pump only.
Operation Condition
Heater on Heater is on as shown in following diagram of heating temperature.
Heater off
Heater is off as shown in following diagram of heating temperature.
Other than heating mode
Error occurred
Forced thermostat off
Heat pump only zone
Temperature of heater on (Thon): Adjustable by function number 62 (Operating temperature
switching of external heaters).
All control temperatures will shift by adjusting “Thon”.
Outdoor temperature zone boundary A and B: Adjustable individually by function setting number
66 and 67.
External heater output
Tr: Room temperature
Ts: Set temperature
Thon: Heater on temperature
Off
On
Tr-Ts ≥ 0.9°F
(0.5°C)
Tr-Ts
Tr-Ts (=Thon) ≤ -0.9°F
(
-0.5°C)
Outdoor temperature zone
Heat pump only zone
(Heat pump)
Combination zone
(Heat pump + Heater)
Heat pump prohibition zone
(Heater)
B: 42.8°F (6°C)*
A: -4°F (-20°C)*
B + 3.6°F (2°C): 46.4°F (8°C)
A + 3.6°F ( 2°C): -0.4°F (-18°C)
Outdoor temp.
*: Adjustable by function setting 66 and 67
2-4. Details of function
- (05-24) - 2. External input and output
FIELD
WORKING
FIELD
WORKING