Maintenance And Servicing; To Replace A Heating Element - Barnstead 47900 Operation Manual

Maintenance and Servicing

Warning
To avoid electrical shock, this furnace
must always be disconnected from the
power supply prior to maintenance and
service.
Perform only maintenance described in
this manual. Contact an authorized deal-
er or our factory for parts and assistance.
Refer servicing to qualified
personnel.
Note
The ceramic hearth collar may crack.
This is a normal condition and will not
affect the performance of the hearth col-
lar.
44

To Replace a Heating Element

1. Disconnect the furnace from the
power supply.
2. Remove the back terminal cover of
the furnace. (Note placement and
connection of wires.)
3. Loosen the nuts on the terminal points
of the four heating element lead wires
and remove the element wires from
the terminals.
4. Loosen the thermocouple hold-down
clip and carefully remove the thermo-
couple from the rear of the furnace
chamber.
5. Remove both the back of the furnace
and the blanket insulation.
6. Grasp the element lead wires and pull
out both elements and the back
chamber insulation.
7. Replace the defective element.
8. Reverse the disassembly procedure,
making sure you thread all element
lead wires through the insulating
porcelain bushings on the back of the
furnace and cut off any excess ele-
ment lead wire after securing the
leads to the terminal points.
9. Reconnect the furnace to the power
supply.
10. Test the operation of the furnace.