User Guide

6 © Copyright 2008 TAC All Rights Reserved. F-18782-3
CHECKOUT
After installing a thermostat, make an initial check of the switching action. Remove the
thermostat cover by removing the two (2) thermostat cover screws. Verify the switch action
by listening to and watching the switch contacts, using a volt-ohm meter between the proper
sides of the switch, or by observing the controlled device.
1. Turn each setpoint dial to a temperature above ambient. First the "R" contact should
make and then the "R1" contact should make.
2. Turn the setpoint dial setting down gradually. First the "B1" contact should make and
then the "B" contact should make.
CALIBRATION
All thermostats are calibrated at the factory and normally do not require any such attention.
However, if recalibration is necessary for any reason, proceed as follows:
1. Disconnect power to thermostat.
2. Set the adjusting dial to correspond to actual room temperature.
3. Remove thermostat cover, remove screw that secures right-hand side of insulator, fold
back insulator, and remove contact cover. (See Figure-3 .)
Caution: Do not breathe on the thermostat or handle excessively as this affects the
accuracy of the final calibration.
4. If the right contact blade is not made to the "R" contact, use a 3/16" open end wrench
(TOOL-11) to turn calibration screw clockwise (looking at head of screw) until blade just
makes "R" contact.
Note: Each complete revolution of the screw changes calibration approximately 6°F
(3.3°C).
5. If the right contact blade is made to the "R" contact, turn the calibration screw slowly
counterclockwise until the element makes the "B" contact.
6. Repeat steps 4 and 5 for the left contact blade. Thermostat is now properly calibrated.
7. Replace contact covers, insulator, and thermostat cover.
8. Restore power to thermostat.
9. Recheck calibration about 30 minutes later to be sure heat from handling did not result
in erroneous setting.
Figure-3 Part Identification.
Optional
Heat
Cover
Screws
Bimetal
Bimetal
Between
Stage
Differential
Calibration
Screw
Insulator
"R1" Contact
(2nd Stage
"B1" Contact
(1st Stage
Detent
Magnets
"R" Contact
(1st Stage
Contact Covers
"B" Contact
(2nd Stage
Optional Night
Depression
Dial
Calibration