Outline of Control (Indoor Unit) SiAF332111E
86 Part 4 Functions and Control
3.8 Freeze-Up Prevention Control
Freeze-Up Prevention by Off Cycle (Indoor Unit Individual Control)
When the temperature detected by liquid pipe temperature thermistor of the indoor heat
exchanger drops too low, the unit enters freeze-up prevention control in accordance with the
following conditions, and is also set in accordance with the conditions given below. (Thermostat
OFF)
When freeze-up prevention is activated, the airflow rate is fixed to L tap. When the following
conditions for cancelling are satisfied, it will reset.
Conditions for starting:
Liquid pipe temperature ≤ – 1°C (for total of 40 minutes)
or
Liquid pipe temperature ≤ – 5°C (for total of 10 minutes)
Condition for cancelling:
Liquid pipe temperature ≥ +7°C (for 10 minutes continuously)
Concept of freeze-up prevention control
System avoids freeze-up
For comfort, system avoids unnecessary thermostat ON/OFF
For ensuring compressor reliability, system avoids unnecessary compressor ON/OFF
When freeze-up prevention control starts, system makes sure the frost is completely removed.
System avoids water leakage.
When the indoor unit is a round flow or multi flow type, if the air outlet is set as dual-directional
or tri-directional, the starting conditions will be changed as follows.
Liquid pipe temperature 1°C (for total of 15 minutes)
or
Liquid pipe temperature 0°C (for 1 minute continuously)
During freeze-up prevention control, the airflow rate is fixed to LL.
(The cancelling conditions are same as the standard.)
Normal operation
Start
Cancel
Liquid pipe
temperature
–5ºC
0ºC
+7ºC
10 min.
10 min.
Freeze-up prevention control
Forced OFF by thermostat
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