To Replace A Chromel/Alumel Thermocouple - Barnstead 47900 Operation Manual

M
To Replace a Chromel/Alumel
Thermocouple (All Furnaces)
1. Disconnect the furnace from the
power supply.
2. Remove both back covers. (Note
placement and connection of wires.)
3. Remove the clip holding the thermo-
couple in place (1 screw), and
remove the two screws on the ther-
mocouple terminals.
4. Remove the thermocouple. (Note:
first pull the thermocouple straight
out of the hole in the chamber to
avoid damage to the insulation.)
5. Guide the looped ends of the new
thermocouple through the plastic
bushings with the red (-) lead to the
right as you face the back of the fur-
nace.
6. Insert the thermocouple straight
through the hole in the chamber.
7. Secure the thermocouple with clip
and screw. Connect the looped ends
of the thermocouple to the terminals
with "+" to "+" (yellow) and "-" to "-"
(red) wires. A polarity test of the ther-
mocouple and lead wire is easily
made with the use of a magnet. On
a Chromel/Alumel thermocouple and
lead wire, the non-magnetic wire is
positive (+) and the magnetic wire is
negative (-).
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AINTENANCE AND ERVICING
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