User Guide
6 © Copyright 2008 TAC All Rights Reserved. F-24576-4
2. To calibrate the cooling dial, the heating dial must first be
turned to the 57°F setting. This moves the heating bimetal
away from the deadband lever. Turn screw “B” to obtain
10.5 psig. If there is a difference between the ambient
temperature and the dial reading, rotate the dial gently to
its stop and continue rotating the screw, slipping the
screw inside the dial. Rotate the dial back to again obtain
10.5 psig. If the dial does not match the ambient
temperature, a second try may be required.
3. Position the heating and cooling dials to the desired
setting and replace the cover.
Reverse-Acting Models
The reverse-acting models are calibrated to have a 5.5 psig
branch pressure when the cooling dial is positioned at ambient
temperature, and 10.5 psig when the heating dial is positioned
at ambient temperature.
To calibrate the reverse-acting models, refer to Figure-11 and
proceed with calibration as outlined under the procedures for
the direct-acting models.
Note:
If, for some reason, a thermostat gets completely out
of adjustment and does not respond to the preceding
calibration, first adjust screws “B” and “C” until, by
observation, neither the heating nor cooling bimetals are
touching the deadband lever. Then proceed with the
calibration as outlined.
Calibrating
Screw "C"
Heating
Dial
Heating Setpoint
and Stop
Cooling Setpoint
and Stop
Cooling
Dial
Calibrating
Screw "B"
Calibrating
Screw "A"
Branch
Pressure
Tap
Direct-Acting
H
E
A
T
I
N
G
74
72
7
0
68
66
C
O
O
L
I
N
G
7
8
76
74
7
2
7
0
6
8
Cooling Bimetal
Heating Bimetal
Dead-Band
Lever
Sensor Ball
Figure-10 Direct-Acting Calibration.
C
O
O
L
I
N
G
6
8
70
72
74
76
78
H
E
A
T
I
N
G
66
68
70
72
74
Calibrating
Screw "B"
Cooling
Dial
Cooling Setpoint
and Stop
Heating Setpoint
and Stop
Heating
Dial
Calibrating
Screw "C"
Calibrating
Screw "A"
Branch
Pressure
Tap
Reverse-Acting
Cooling Bimetal
Heating Bimetal
Dead-Band
Lever
Sensor Ball
Figure-11 Reverse-Acting Calibration.