Chromalox PK410-1 - Manual (Page 3)

SETTING
WR-90 controls have an adjustable differential. The movable
indicator points to the temperature at which the contacts open. The
fixed indicator points to the temperature at which the contacts close.
The difference between these two indicators is the differential.
To set the control, proceed as follows:
1. Use screwdriver in slot and turn the dial so the fixed indicator
“B” points to the temperature at which heating is to start.
2. Turn the differential adjusting screw “C” until the movable
indicator “D” points to the temperature at which the heating is
to stop.
UNITING LIQUID IN THERMOMETER
Sometimes the red liquid inside the thermometer on the WR-
80 becomes separated during shipment. The thermometer will not
read correctly when this red liquid is separated at any point. If the
red liquid in the thermometer of this thermostat has become sepa-
rated it may be reunited as follows:
1. Remove the thermostat from the wall, and straighten out the
four prongs so the cover can be removed to expose the ball of
the thermometer.
2. Hold the lighted end of a cigarette or a match at such a distance
from the SIDE of the ball of the thermometer so the red liquid
rises SLOWLY in the stem of the thermometer.
3. When the lowest separation goes into the reservoir, immedi-
ately remove the heat and blow on the thermometer.
CAUTION: If there is more red liquid in the stem of the ther-
mometer above the lowest separation than there is below it, it is
best to replace the thermometer.
CALIBRATION
Figure 4
Figure 5