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Reverse Cycle Defrosting Heat Pump Mode
Reverse Cycle Defrosting During Heat Pump Mode
Defrost Enable
The reverse cycle defrost will begin when either:
1. The control detects that the outdoor coil
temperature has remained below 14°F for
more than 3 minutes.
-OR-
2. The accumulated run time of the compressor
is greater than 3 hours provided that the
outdoor temperature stays below 32°F.
REVERSE CYCLE DEFROST
Outdoor Fan
Compressor
Indoor Fan
Reversing
Valve
Heaters
On
OȺ
ON (Reverse Cycle)
Max 9 mins
Min 3 mins
OȺ
OȺ
On
OnOn
On On On
On
On On
T1
T2
Stage 1 or 2 Heat
Stage 3 Heat
Reverse Cycle
Stage 3 Heat
Stage 1 or 2 Heat
Defrost Operating Sequence
When either of the conditions are detected, the
Zoneline will initiate a reverse cycle defrost.
The following steps comprise the reverse cycle
defrost:
1. Immediately stop heat pump operation.
2. Run Stage 3 heating until the room
temperature is satis¿ed.
3. Run reverse cycle defrost (cooling mode
without fans) until the outdoor coil
temperature reaches 62°F or 9 minutes of
defrost time.
4. Run a Stage 3 heating cycle to satisfy room
temperature.
5. Resume normal heating mode logic.
Reverse Cycle Defrost will be controlled as a function of compressor run time and outdoor coil temperature.
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