20
CHS-SVN011C-EN
Defrost Control Instructions
(F0) Units
Dial description
Two simplified dials control defrost cycle initiation and
duration. The outer dial rotates once every 24 hours to
establish cycle initiation. It is calibrated in hours 1-24 and
accepts timer pins which are inserted opposite desired
cycle initiation times. Up to 6 defrost cycles are obtainable
in a 24 hour period.
The inner dial controls the duration of each defrost cycle
and rotates once every 2 hours. It is calibrated in 2 minute
increments up to 110 minutes and has a hand set pointer
which indicates the length of the cycle in minutes. This
timer also has a solenoid which is activated by a
thermostat or pressure switch to terminate defrost.
To set timer
1. Screw timer pins in outer dial at desired starting time.
2. Press in on bronze pointer on inner dial and slide it to
indicate cycle length in minutes.
3. Turn time setting knob until time of day pointer is
pointing to
4. number on outer dial corresponding to actual time of
day at that moment.
(F1) Units
The electric defrost is initiated by an ABB multi-function
timer (see picture for factory settings). The defrost cycle
allows the coil to clear of all frost before returning to the
cooling cycle. If this does not occur the timer settings may
need to be adjusted. For changing the settings see the
section below on TIMERS. The cooling times and defrost
times are preset but may need to be adjusted depending
on the job specific conditions.
The two timers on the left are to provide a delay between
VFD and soft start fan selection. The settings on the two
timers on the left should never be changed, doing so may
cause harm to the VFD or soft start. The third timer from
the left controls length of the cooling cycle run time. The
far-right timer controls the length of defrost cycle run time.
EXAMPLE:
To change the cooling cycle from 50 minutes
to 10 hours with a 30 minute defrost cycle. This will
achieve approximately 2 defrost periods of 30 minutes in
a 24-hour period. On the third timer from the left change
the “Time selector” to “10h” and the “Time value” to “10”
(sets cooling cycle to 10 hours). On the fourth timer from
the left change the “Time value” to “3” (sets defrost cycle
to 30 minutes).
For a more detailed description of the timer functions see
the timer manual located in the inside the control panel.
See below for typical “Lead/Follow” mode timer settings
for 50 minute cool cycle and 20 minute defrost cycle:
VFD timer
Soft start
Timer
Cooling cycle
Timer
Defrost cycle
Timer
