Technical Instructions Document No. 155-071P25 TH 357-1 February 15, 2022 POWERS™ CONTROLS TH 357 LIMITEM® Remote Bulb Thermostat Description The TH 357 LIMITEM is a gradual-direct acting thermostat for air temperature control. This pneumatically operated instrument senses a temperature and passes on a pneumatic signal whose pressure is proportional to the temperature sensed. The sensing element is liquid-filled, and is available in remote and averaging bulb styles.
Technical Instructions Document No. 155-071P25 February 15, 2022 TH 357 LIMITEM Remote Bulb Thermostat Specifications Operating range Control Action Temperature response Maximum supply air pressure Maximum ambient temperature of case Air connection Shipping weight Dimensions See Table 1 Direct 0.5°F (0.3°C) 30 psi (207 kPa) 180°F (82°C) 1/8-inch NPT 2 lbs (0.
TH 357 LIMITEM Remote Bulb Thermostat Technical Instructions Document No. 155-071P25 February 15, 2022 Installation • A 1/8-inch NPT opening in the LIMITEM body is provided for mounting. Mounting the TH 357 LIMITEM body. (See Figure 2.) • The mounting bracket (furnished with thermostat) may be attached to any flat surface and the thermostat body threaded onto the protruding pipe nipple.
Technical Instructions Document No. 155-071P25 February 15, 2022 TH 357 LIMITEM Remote Bulb Thermostat Installation, continued Figure 3. Remote Bulb Holder Kit 808-517. Figure 4. Clips, 356-115 and 7421700060. Figure 5. Clip Mounted on Coil. Figure 6. Copper Well Grainger number 38Y210. Averaging bulb mounting Averaging bulbs require some means of support for the bulb and capillary. • Use a coil clip, Part No. 356-115 (Figure 4 and Figure 5) or a capillary clip, Part No.
TH 357 LIMITEM Remote Bulb Thermostat Calibration To change setpoint To calibrate Technical Instructions Document No. 155-071P25 February 15, 2022 1. Remove the cover. 2. With a screwdriver, turn the dial adjustment screw to change to the desired setpoint. See Figure 8. 1. Using a test thermometer, accurately measure the temperature at the bulb. 2. Set the dial to the bulb temperature by turning the dial adjustment screw with a screwdriver. NOTE: You must use a screwdriver.
Technical Instructions Document No. 155-071P25 February 15, 2022 Sensitivity Adjustment TH 357 LIMITEM Remote Bulb Thermostat The sensitivity adjustment is factory set with the sensitivity spring tab in position 6 of the spring retainer. This is approximately mid span of the sensitivity. Move the sensitivity spring to a lower slot number for more gradual setting. Move the sensitivity spring to a higher slot number for more positive setting. See Table 2. To change the sensitivity: 1.
TH 357 LIMITEM Remote Bulb Thermostat Troubleshooting Technical Instructions Document No. 155-071P25 February 15, 2022 If the LIMITEM® fails to operate properly, use Table 3 as a troubleshooting guide. Ensure that the thermostat receives 18 to 30 psi (124 to 207 kPa) of clean, dry, oil-free supply air. Also, use a test gauge with a length of 3/16-inch ID rubber hose to measure the return pressure at the test port if permanent gauges are not available . Service The LIMITEM cannot be serviced.
Technical Instructions Document No. 155-071P25 February 15, 2022 TH 357 LIMITEM Remote Bulb Thermostat Figure 11. Construction of the Remote Bulb LIMITEM®. Table 4. Parts List. Item Part Table 4. Parts List, Continued. Qty Part Number Item – 21 22 – – – – 23 1 Cover 1 2 Dial 1 3 4 5 6 Lock Plate Bridge Sensitivity Spring No. 6-32 × 1-3/8” Lg.Fil. head screw 1 1 1 4 7 8 9 10 11 Housing Ring Ball Lower Diaphragm Spring No. 3-48 × 3/4" Lg.Fil.
