Phason
FHC-1D user manual
11140706
9
Off set-back/IDLE SET Mode (OSB)
OSB is the number of degrees Celsius or Fahrenheit below the TEMP SET that the fan will switch
between OFF and IDLE. IDLE mode provides minimum ventilation at temperatures below the
TEMP SET. For more information, see
Example 1, operation in off set-back (OSB) mode
on page
13.
To display and adjust OSB
1.
Click the switch to the right to start at the beginning of the parameter list.
2.
Click the switch to the left two times and then hold. The display flashes between
oS
and the
setting. If
id
is displayed, the control is in IDLE SET mode.
3.
Use a small flat screwdriver to adjust the internal trimmer to the desired OSB or turn the
trimmer fully clockwise to put the control into IDLE SET mode. See section C of the diagram
on page 4 for trimmer location.
Adjusting minimum ventilation in OSB mode
There must be a temperature probe connected before adjusting the minimum ventilation.
1.
Turn the
Idle Speed
knob fully counter-clockwise and then back ¼-turn clockwise.
2.
Click the front cover switch to the right and hold while turning the
Temperature
knob fully
clockwise and then release the switch. The fan should not be running
3.
Click the front cover switch to the right and hold while slowly turning the
Temperature
knob
counter-clockwise. When the fan runs full speed, release the front cover switch and the
Temperature
knob.
The fan runs at maximum speed for approximately three seconds, and then at IDLE. The
Temperature
knob should be approximately one °F higher than the temperature.
4.
Slowly adjust the
Idle Speed
knob until a satisfactory IDLE has been reached. A voltmeter is
helpful for determining the voltage. If you are unsure, see your fan dealer for the minimum idle
voltage for your fan motor.
5.
Click the front cover switch to the right and adjust the
Temperature
knob to the desired
temperature.
6.
Release the switch.
