Temco DV1000N/P Installation And Operating Manual page 30

Temco DV1000/1200/1400 Series
System Checks
(continued)
Problem
Pilot drops out.
No gas to main burner
Thermostat/wall switch
will not cycle main
burner.
30
Possible Cause
Defective thermocouple.
(mv Plus systems)
Defective thermo-generator.
(Millivolt system)
Defective safety magnet.
(mv Plus systems)
Defective Safety Magnet
(Millivolt system)
Pilot orifice blocked.
Wrong pilot orifice.
Low gas pressure to appliance.
Pilot not lit.
Control knob not in ON
position.
Thermostat not in ON position.
Solution
Verify that thermocouple is not kinked or damaged.
Check open circuit voltage of thermocouple. Voltage
should be between 18mv and 28mv. If voltage is
less than 14mv, replace thermocouple.
After the pilot has been lit for approximately three
minutes, and only the thermo-generator wire con-
nected to the main operator head, measure the volt-
age across TPTH and TP. This open circuit voltage
should be between 500mv and 750mv. Tune the
pilot adjustment screw until the mv reading falls
within these parameters. (Counter-clockwise
increases mv reading, clockwise decreases)
Verify operation of safety magnet in the following
manner.
(A) Depress and hold pilot button.
(B) Verify open-circuit thermocouple voltage as de-
scribed in previous step.
(C) Reconnect thermocouple to valve.
(D) Measure the Millivoltage between the solder
button on the base of the safety magnet, and the
valve body. If the mv reading is above 6mv for
vented appliances, or 8.5 mv for un-vented
appliances, and the safety magnet does not hold,
replace the valve.
(E) If closed circuit mv reading is the same as the
open circuit reading, the coil is electrically open.
Replace the valve.
Verify operation of safety magnet in the following
manner.
(A) Remove all wires from the terminals of the main
operator.
(B) Measure the electrical voltage between the term-
inals TPTH and TP. If the voltage is above 110mV
and the safety magnet does not hold, replace the
valve.
Replace orifice with a new orifice of the exact size
and type.
Replace the orifice with a new orifice supplied
specifically for the appliance and gas type in
question.
With the main burner functioning, adjust the inlet
pressure regulator to supply gas to the appliance
within the design parameters of the appliance manu-
facturer. (Typically 7"NG, 11"LPG).
Light pilot and wait for thermo-generator to heat up
sufficiently to power the main operator. If pilot fails
to light, or hold, refer to above sections.
Rotate OFF/PILOT/ON control knob to the ON posi-
tion.
Turn thermostat ON, and adjust temperature control
to call for heat.
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