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Technical Instructions

Document No. 155-070P25

TH 356-1

September 24, 2004

TH 356 Limitem Rigid Bulb

Thermostat

Description

The TH 356 Rigid Bulb Limitem is a pneumatically operated thermostat available either

as direct acting or reverse acting in a variety of ranges.

Features

• Copper motor tube and invar steel rod sensing element

• Two-valve design eliminates wasting of air

• 18-inch (457 mm) bulb useful where stratification occurs

• Flange, locknut and screws for duct mounting included

Product Numbers

Table 1.

Product

Number

Operating Range Action

356-0750 30 to 180°F (-1 to 82°C)

356-0012 0 to 100°F (-18 to 38°C)

Direct

Acting

356-1005 30 to 180°F (-1 to 82°C)

356-1006 100 to 250°F (38 to 121°C)

356-0013 0 to 100°F (-18 to 38°C)

Reverse

Acting

Application

The 356 Rigid Bulb Limitem is recommended for use in controlling duct air

temperatures such as mixed air or discharge air. It can also be used as a high or low

temperature limit control. In unit ventilator applications it is used as a low limit control.

When used with a well, it can be used for water temperature control.

Siemens Building Technologies, Inc.

Summary of content (8 pages)

PAGE 1
Technical Instructions Document No. 155-070P25 TH 356-1 September 24, 2004 PowersTM Controls TH 356 Limitem Rigid Bulb Thermostat Description The TH 356 Rigid Bulb Limitem is a pneumatically operated thermostat available either as direct acting or reverse acting in a variety of ranges.
PAGE 2
Technical Instructions Document No. 155-070P25 September 24, 2004 Specifications Accessories Operating range Normal air supply pressure Maximum supply air pressure Maximum external pressure on bulb Maximum ambient temperature case bulb 30 to 180°F 100 to 250°F 40 to 120°C 0 to 100°F -20 to 40°C Factory sensitivity setting Sensitivity range adjustable Temperature response Mounting Air connection Shipping weight Dimensions Bulb length Case Flange O.D.
PAGE 3
TH 356 Limitem Rigid Bulb Thermostat Technical Instructions Document No. 155-070P25 September 24, 2004 Operation The copper motor tube and invar steel rod average temperature changes by measuring the difference in expansion between the two metals. This positions the two-valve mechanism in response to the slightest temperature changes.
PAGE 4
Technical Instructions Document No. 155-070P25 September 24, 2004 Installation NOTE: Duct Mounting (See Figure 3) Flange, lock nut and sheet metal screws are provided for duct mounting. Calibrate the Limitem for your application after installation. 1. Remove the flange from the Limitem and use the flange as a template. Mark the location of the center hole and three screw holes. Drill the holes. 2. Slip the flange over the rigid bulb and secure with the lock nut. 3.
PAGE 5
TH 356 Limitem Rigid Bulb Thermostat Technical Instructions Document No. 155-070P25 September 24, 2004 Installation, continued Figure 4. Swivel Flange Mounting Kit part No. 356-090. Well Mounting (See Figure 5) 1. Exercise care when installing the limitem into a well. 2. The Limitem must fit freely in the well to operate properly. 3. Screw the limitem into the well finger tight. 4. Tighten the set screw on the well to hold the limitem securely. The installation is now complete. Figure 5.
PAGE 6
Technical Instructions Document No. 155-070P25 September 24, 2004 Calibration, continued To calibrate 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. Do not attempt to change the dial by rotating it with your hand. 3. If permanent return air gauge is not installed, use the pressure test port. See Figure 6 for its location. 4.
PAGE 7
TH 356 Limitem Rigid Bulb Thermostat Technical Instructions Document No. 155-070P25 September 24, 2004 Sensitivity Adjustment, continued Table 1. Slot No. Sensitivity Psi/°F 1 2 3 4 5 6 7 8 9 10 11 0.29 0.44 0.64 0.89 1.03 1.22 1.41 1.61 1.80 2.0 2.0 Figure 8. Sensitivity Spring Setting. Troubleshooting If the limitem fails to operate properly, use Table 3 as a troubleshooting guide. Make certain the thermostat receives 18 to 30 psi (124 to 207 kPa) of clean, dry, oil-free supply air.
PAGE 8
Technical Instructions Document No. 155-070P25 September 24, 2004 Figure 9. Construction of the Rigid Bulb Limitem. Table 4. Parts List. Table 4. Parts List, continued. Item Part Qty.