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INSTALLATION AND OPERATING INSTRUCTIONS FOR TYPE XT
EXPLOSION RESISTANT AND MOISTURE RESISTANT THERMOSTATS
1.0 GENERAL
The XT thermostat series features Norseman’s unique x-Max track and trolley wiring system (patent pending). The unit can be
®
field converted from externally adjustable to tamper-proof adjustable in minutes.
1.1 Type XT thermostats are suitable for both Moisture resistant and Explosion resistant applications. Check the thermostat
nameplate to ensure that the thermostat area classification is suitable for the hazardous area classification.
TEMPERATURE DIFFERENTIAL
Usually 5% of the range, but subject to variation depending on the application. Such factors as rate of temperature change,
location of sensing bulb, etc. will affect the differential.
OVERSHOOT
This control works on the principle of liquid expansion. A temperature rise expands the liquid in a bellows which operates a
switch. Overshoot in excess of 25°C above the highest set point can produce expansion forces that will possibly rupture the
bellows or at least cause a deformation that will affect calibration. Calibration shifts result in the process operating at higher
temperatures than indicated on the dial. Ultimate failure of this style of control will result in the load being energized
continuously. Therefore it is very important to include a high limit in the control circuit as dictated by the electrical code.
SENSING BULB
When handling the sensing bulb, do not kink or squeeze the bulb or capillary. Style 9, / " diameter bulbs may be bent to a
minimum radius of / ". Style 4, / " diameter bulbs may not be bent.
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88
3
16
CAUTION: ALWAYS DISCONNECT POWER BEFORE INSTALLATION OR SERVICING.
2.0WIRING
2.1All units must be wired by qualified personnel to electrical code requirements. Conduit, conduit seals and fittings shall be
approved for intended use.
2.2Disconnect the power to the unit. Remove knurled cover.
2.3Make all necessary electrical connections. Models XT*****1 are equipped with a S.P.S.T thermostat suitable for use as a
switching component for single phase applications using less than 240 V / 30 A, 277 V / 25 A and 600 V / 15 A. Models XT*****3
are equipped with a D.P.S.T. thermostat suitable for use as a switching component for single or three phase applications using
less than 600 V / 15 A (See Figures 1 and 2 below). Thermostats are suitable for pilot duty only in applications requiring higher
voltages or currents.
Figure 1: Wiring diagram for XT****1 S.P.S.T. Thermostats Figure 2: Wiring diagram for XT****3 D.P.S.T. Thermostats
MI133.rev.2004
3.0CONVERTING FROM TAMPER-PROOF TO KNOB-ADJUST MODE
3.1Disconnect the power to the device. Remove the knurled cover from the housing assembly. Remove the socket-head cap
screw.
3.2Ensuring that the thermostat shaft remains aligned with the cap screw hole, place the knob onto the operating shaft and
thread it into the cap screw hole.
3.3When the operating shaft engages with the thermostat shaft, with
light finger pressure, gently spring the thermostat away from the
PRESS
THERMOSTAT
TO SPRING
bracket assembly, as shown in Figure 3 (DO NOT press down on the
steel bracket). Rotate the knob one more full revolution to assure a
positive engagement of the thermostat. Release the thermostat.
3.4Upon release, the thermostat should spring back into its original
position. If the thermostat remains sprung down, a slight twisting of the
knob in both directions should create a positive engagement. The
knob should be able to turn through the entire temperature range but
THERMOSTAT
IN ‘SPRUNG’
POSITION
should not turn one full revolution. If the knob turns completely around,
repeat 3.3.
Figure 3: ‘Springing’ the thermostat
4.0CONVERTING FROM KNOB-ADJUST TO TAMPER-PROOF MODE:
4.1Disconnect the power to the device. Remove the knurled cover from the housing assembly. Using finger pressure, gently
spring the thermostat away from the bracket assembly, as shown in Figure 3 (DO NOT press down on the steel bracket). While
the thermostat is sprung down, rotate the thermostat knob counterclockwise to remove the operating shaft.
4.2Ensuring that the thermostat shaft remains aligned with the operating shaft hole, place the socket-head cap screw into the
hole at the front of the housing and tighten. Replace the knurled cover.
5.0OPERATION
5.1TAMPER-PROOF MODE: To set the thermostat temperature:
5.1.1 Disconnect the power to the unit.
5.1.2 Completely remove the socket-head cap screw from the housing
assembly.
5.1.3 Insert a flat-head screwdriver into the slot cut in the thermostat
SLOT IN THERMOSTAT SHAFT
Figure 4: Thermostat temperature setting
READ TEMPERATURE
HERE
shaft.
5.1.4 Rotate the screwdriver to set the thermostat to the desired temperature. See Figure 4 to determine the temperature
setting. Turning the shaft clockwise increases the set point temperature, counterclockwise rotation decreases the set point
temperature (As a quick check, note that the thermostat will switch at the ambient temperature when the shaft is rotated).
5.1.5 Read the temperature from the front face of unit, as shown in Figure 4.
5.2KNOB-ADJUST MODE: To set the thermostat temperature:
5.2.1 Rotate the knob to set the thermostat to the desired temperature. Turning the shaft clockwise increases the set point
temperature, counterclockwise rotation decreases the set point temperature.
6.0INSTALLATION
6.1The type XT universal mounting bracket is designed for horizontal (knurled cover at the side) or vertical (knurled cover at
the top) mounting. Use the bracket supplied as a template to locate wall holes before attaching the bracket to the thermostat
and affixing the assembly to the wall.
6.2 The model XTW*****L has an external / " NPT fitting for installing into a tank wall. Use an open end wrench to tighten the
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8
fitting to a mating tank fitting. Check for leaks and retighten if necessary.
6.3 All other model XTW thermostats are equipped with aluminum fins for increased temperature sensitivity.
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