10
TP970 AND TP9600 SERIES PNEUMATIC THERMOSTATS
77-9382—1
Fig. 15. TP971 and TP9610 Operation, DAY/AUTO Lever Manually Set to
DAY Position—Main Air Pressure 18 psi (124 kPa).
Fig. 16. TP972A and TP9620A Cross Section Showing
Adjustments and Modular Construction.
BLEED 1
F
FILTER
RESTRICTOR
R
VALVE
UNIT
SECONDARY
BRANCH
S
S
S
B
DAY/AUTO LEVER
MANUAL DAY
LOGIC
MODULE C
LOGIC
MODULE D
SPRING
LOGIC MODULE A
DOTTED LINES INDICATE THE SECONDARY
BRANCH LINE INTEGRAL TO THE TP971C
BRANCH LINE
MAIN LINE
PILOT
CHAMBER
SPRING
BLEED 2
DIAPHRAGM
PORT B2
PORT B1
13 PSI (90 kPa)
DAY
18 PSI (124 kPa)
NIGHT
LOGIC
MODULE B
C6060-1
B
SB
NOZZLE
1
1
When the air supply system returns to its normal daytime
pressure, the DAY/AUTO lever is spring returned to the
AUTO position and the Thermostat returns to normal
operation. The occupant can also return the system to
normal operation by manually switching the DAY/AUTO lever
to AUTO.
In the preceding situation, the P/E switch contacts are
closed. This is because the secondary BLP is under 15 psi
(103 kPa); the DAY/AUTO lever is held in the DAY position
by pressure on Logic Module C; and the Thermostat uses its
daytime bimetal because the airflow through Logic Module
D is closed off.
TP972A AND TP9620A HIGH-CAPACITY,
HEATING/COOLING THERMOSTAT
General
The TP972A and TP9620A (Fig. 16) are high-capacity, two-
pipe, proportioning pneumatic Thermostats with two bimetal
sensing elements.
FLAPPER
THROTTLING RANGE
ADJUSTMENT
COOLING THROTTLING
RANGE ADJUSTMENT
HEATING THROTTLING
RANGE ADJUSTMENT
BRANCH LINE
PRESSURE GAGE PORT
BIMETAL
COOLING
BIMETAL
HEATING
BIMETAL
NOZZLE
CALIBRATION
ADJUSTMENT
NIGHT
SETPOINT KNOB
COOLING
SETPOINT
KNOB
SETPOINT
KNOB (TAB
REMOVED FOR
TP972A1036)
HEATING/COOLING
LOGIC CIRCUIT
VALVE UNIT
C6061-1
HEATING SETPOINT
KNOB FOR TP972A1036
(55-75
°
F (13-24
°
C) RANGE)
AIR CONNECTION
FILTER AND
RESTRICTOR
THERMOMETER
POST
