SERVICE PROCEDURE AG-I
Thermocouple Testing and Replacement
For Models Using Honeywell Gas Control
OPEN CIRCUIT THERMOPILE TESTING
Step 1. Disconnect red and white thermopile wires from the wire harness leading to the gas control.
Step 2. Using a multimeter capable of reading millivolts, check across thermopile leads.
Step 3. Following the instructions located on the lighting instruction label or the lighting instructions located in the installation and operation manual, proceed to light the pilot and allow the gas control to operate for three minutes.
NOTE:
It may be necessary to hold the gas control knob down in the “PILOT” position continuously throughout this test.
In an OPEN CIRCUIT test: |
|
Any reading over 400 millivolts |
|
indicates good thermopile output. |
|
For readings under 400 millivolts |
|
replacement of thermopile is | Figure 5 |
recommended. |
CLOSED CIRCUIT THERMOPILE TESTING
Step 1. Closed circuit testing is the preferred method for testing the thermopile. Following the instructions located on the lighting instruction label or the lighting instructions located in the installation and operation manual, proceed to light the pilot and allow the control to operate for three minutes.
Step 2. Using a multimeter capable of measuring millivolts, measure across thermopile connections at the gas control (see Figure 6).
In a CLOSED CIRCUIT test:
Any reading over 300 millivolts indicates good thermopile output. For readings under 300 millivolts replacement of thermopile is recommended.
Gas Control
Knob
NOTE:
It may be necessary to hold the gas control knob down in the “PILOT” position continuously throughout this test.
Thermopile
Connections at gas
control
Figure 6
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