Fujitsu ASUH30LPAS Design & Technical Manual page 41

 Auxiliary heat pump control by outdoor temperature 1
• External heater output
Operation
Heater on
Heater off
– Temperature of heater on (Thon): Set temperature (Ts) - 0.9 °F (- 0.5 °C)
– Temperature of heater off: Set temperature (Ts) + 0.9 °F (+ 0.5 °C)
Tr-Ts ≥ 0.9°F
(0.5°C)
• Auxiliary heat pump On/Off
– Temperature of heater on (Thon): Adjustable by function number 62 (Operating temperature
switching of heat pump).
– All control temperatures will shift by adjusting "Thon".
Tr-Ts ≥ -1.8°F
(-1°C)
• Outdoor temperature zone
A + 3.6°F ( 2°C): -0.4°F (-18°C)
*: Adjustable by function setting 66
8-4. 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
Tr-Ts
Off
Tr-Ts (=Thon) ≤ -0.9°F (-0.5°C)
On
Tr-Ts
Off
Tr-Ts (=Thon) < -5.4°F (-3°C)
On
Outdoor temp.
Combination zone
( Heat pump + Heater)
*A: -4°F (-20°C)
Heater only zone
Condition
Tr: Room temperature
Ts: Set temperature
Thon: Heater on temperature
Tr: Room temperature
Ts: Set temperature
Thon: Heater on temperature
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8. External input and output