02-12
2-8-3 Defrost Operation Control
Accumulated heating operation time is 40 minutes or longer
(Accumulated heating operation time is reset at the end of cooling operation or defrosting operation.)
And
One of Heat-Ex satisfies condition or or below
Condition : Accumulated operating time is 150 minutes* or longer:
"Heat exchange liquid temperature (TH9 and TH10) 28.4°F ( -2°C)"
*75 minutes: when indoor unit connection capacity 90% at 1 outdoor unit connection.
Condition : Accumulated time 10 minutes:
"Heat exchange liquid temperature (TH9 and TH10) Defrosting Start Judgment Temperature*
And
"During heat exchange liquid temperature keeps droping "
*Defrosting Start Judgment Temperature(°F) = 0.8 x Outdoor temperature (°F) - 52.9
However, -17.7°F to 21.2°F
If the calculated result is lower than -17.7°F, the judgment temperature is defined as -17.7°F
If the calculated result is higher than 21.2°F, the judgment temperature is defined as 21.2°F
(Defrosting start judgment temperature are determined by the outdoor temperature.)
*Defrosting Start Judgment Temperature(°C) = 0.8 x Outdoor temperature (°C) - 11.6
However, -27.6°C to - 6°C
If the calculated result is lower than -27.6°C, the judgment temperature is defined as -27.6°C
If the calculated result is higher than -6°C, the judgment temperature is defined as -6°C
(Defrosting start judgment temperature are determined by the outdoor temperature.)
: Less than 10 minutes operation at outdoor temperature below 35.6°F (2°C) occured 20 times
< Defrosting start condition >
< Defrosting end condition >
Condition
At all outdoor units, heat exchange liquid temperature Defrosting End Judgment Temp.* and 180sec elapsed,
and all of outdoor unit's Suction temperature - Low pressure saturation temperature 10°F (5°C)
or
When 15 minutes have elapsed from the start
*Defrosting End Judgment Temperature(°F)= 0.39 x outdoor temperature(°F) + 54.8
-However, 41.0°F to 53.6°F range
If the calculated result is lower than 41.0°F, the judgment temperature is defined as 41.0°F.
If the calculated result is higher than 53.6°F, the judgment temperature is defined as 53.6°F.
*Defrosting End Judgment Temperature(°C)= 0.39 x outdoor temperature(°C) + 12.7
-However, 5°C to 12°C range
If the calculated result is lower than 5°C, the judgment temperature is defined as 5°C.
If the calculated result is higher than 12°C, the judgment temperature is defined as 12°C
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