Fujitsu ASUH18LMAS Service Manual page 202

 Auxiliary heater control by outdoor temperature 1
This control selects heat pump or external heater according to the outdoor temperature. →hen out-
door temperature is high, the heating is performed by using heat pump only.
Operation
Heater on
Heater off
• 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-Ts ≥ 0.9°F
(0.5°C)
• Outdoor temperature zone
B + 3.6°F (2°C): 46.4°F (8°C)
A + 3.6°F ( 2°C): -0.4°F (-18°C)
*: Adjustable by function setting 66 and 67
2-4. Details of function
Heater is on as shown in following diagram of heating temperature.
• Heater is off as shown in following diagram of heating temperature.
• Other than heating mode
• Error occurred
• Forced thermostat off
• Heat pump only zone
Tr-Ts
Off
Tr-Ts (=Thon) ≤ -0.9°F
On
Outdoor temp.
Heat pump only zone
B: 42.8°F (6°C)*
Combination zone
(Heat pump + Heater)
A: -4°F (-20°C)*
Heat pump prohibition zone
Condition
Tr: Room temperature
Ts: Set temperature
(-0.5°C)
Thon: Heater on temperature
(Heat pump)
(Heater)
- (05-28) -
2. External input and output