Temco DV5200MB Installation And Operating Manual page 27

System Checks
(continued)
Problem
Thermostat/wall switch
will not cycle main
burner.
Thermostat/wall switch
will not cycle mian
burner.
78674
Possible Cause
Pilot not lit.
Control knob not in ON
position.
Thermostat not in ON position.
Thermo-generator output
voltage not within design
parameters.
Defective thermostat or
thermostat wiring
Defective wall switch.
Excessive wire resistance.
Valve wired wrong.
Solution
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.
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
voltage acrossTPTH and TP. This open circuit volt-
age should be between 500mv and 750mv. Tune the
pilot adjustment screw until the mv reding falls with-
in these parameters. (Counterclockwise increases
mv reading, clockwise decreases) If unable to meet
minimum requirements, repalce thermo-generator.
(A) With the pilot adjusted properly, ( After the pilot
has been lit for approximately three minutes, and
only the thermo-generator wire connected to the
main operator head, measure the voltage across
TPTH and TP. This open circuit voltage should be
between 500mv and 750mv. Tune the pilot adjust-
ment screw until the mv reading falls within these
parameters. Counterclockwise increases mv read-
ing, clockwise decreases), place a jumper wire be-
tween TPTH and TH. Take a mv reading across the
TPTH and TP terminals on the valve. This closed
circuit voltage should not fall below 300mv. Record
reading.
(B) Remove jumper wire form the TPTH and TH
connections, and reconnect the thermostat wires to
the same terminals. Take the closed circuit voltage
as described in the previous step. If the mv reading
drops below 150mvm, excessive resistance exists
in the thermostat circuit, and must be isolated and
eliminated.
Repeat the above troubleshooting items covered
under "Defective thermostat or thermostat wiring",
except substitute the words "wall switch" where the
word "thermostat" appears in the instructions.
Make certain that all mv connections are made us-
ing wire of the proper size. (Reference Page 23).
Thermo-generator leads must be connected to the
TPTH and TP connections of the main operator.
Thermostat wires must be connected to the TPTH ,
and TH terminals of the valve.
Temco DV5200 Series
27