Johnson Controls DOA096B21S Series, Engineering Manual

Page: 27 / 48

DOAS
TC-16005-rev.2
2-15
(2) Freeze Protection Control
DOAS operates the forced heating operation for freeze protection of the heat exchanger if the outdoor
air inlet temperature is 32
o
F (0
o
C) or less during the cooling or airflow operation.
However, the operation is stopped if the outdoor air inlet temperature is 19.4
o
F (-7
o
C) or less, or the
temperature in the circuit is decreased.
In addition, the operation is stopped when the condition is not available for the heating operation.
(The operation connected DOAS and other indoor units, etc.)
Yes
Yes
Yes
Yes
No
No
No
No
Outdoor
Air Inlet
Temp.
Thermo-OFF
I.U Fan: OFF
Outdoor
Air Inlet
Temp.
Forced Heating Operation: ON Forced Heating Operation: OFF
< 32
o
F (0
o
C)
< 35.6 o F
(2
o
C)
> 35.6
o
F (2
o
C)
> 32
o
F (0
o
C)
I.U. : Indoor Unit
Operation
Forced
Heating
Operation
Forced Heating Control
I.U Fan: OFF
I.U Fan: ON
No
Yes
Yes
No
No
No
Yes
Yes
Outdoor
Air Inlet
Temp.
< 19.4
o
F (-7
o
C)
for 3 min.
Outdoor
Air Inlet
Temp.
> 19.4
o
F (-7
o
C)
for 3 min.
Forced Stop Operation
: ON
Forced Stop Operation
: ON
Defrosting
Operation
Heating
Operation
Forced Stop Control 1
No
Compressor: OFF
I.U Fan: OFF
Yes
Forced Stop Operation
: OFF
Forced Stop Operation
: OFF
Thermo-ON
I.U Fan: ON
Forced Stop
Operation
Yes
No
No
No
Yes
Forced Stop
Operation
Forced Stop Control 2
Yes
Thermo-OFF
I.U Fan: OFF
Thermo-ON
I.U Fan: ON
10 min. has passed
Since Forced Stop
I.U. : Indoor Unit
Outdoor
Air Inlet Temp.
< 32 o F (0 o C) and
I.U Heat Exchanger
Liquid Pipe (Freeze) Tem.
< 39.2
o
F (4
o
C)
for 30 min.