Temco Tool 41DVN - Manual (Page 32)

32
41DVN / DVSN Direct Vent Gas Fireplace
20009999
System Checks (continued)
Problem Possible Cause Solution
Thermo-generator output After the pilot has been lit for approximately three
voltage not within design minutes, and only the thermo-generator wire connected
parameters. 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 adjustment
screw until the mV reading falls within these parameters.
(Counter-clockwise increases mV reading, clockwise
decreases) If unable to meet minimum requirements,
replace thermo-generator.
Defective thermostat or (A) With the pilot adjusted properly, ( After the pilot has
thermostat wiring. 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 be
tween 500mV and 750mV. Tune the pilot adjustment
screw until the mV reading falls within these param-
eters. Counterclockwise increases mV reading,
clockwise decreases), place a jumper wire between
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 read-
ing.
(B) Remove jumper wire from the TPTH and TH con
nections, 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 150mV, excessive resistance exists in
the thermostat circuit, and must be isolated and
eliminated.
Thermostat/wall switch Defective wall switch. Repeat the above troubleshooting items covered under
will not cycle main “Defective thermostat or thermostat wiring”, except
burner. substitute the words “wall switch” where the word
“thermostat” appears in the instructions.
Excessive wire resistance. Make certain that all mV connections are made using
wire of the proper size. (Reference Page 26).
Valve wired wrong. Thermo-generator leads must be connected to the
TPTH and TP connections of the main operator. Ther
mostat wires must be connected to the TPTH , and TH
terminals of the valve.
Main burner lights in Main operator coil defective. Verify electrical resistance of main operator coil in the
the PILOT position. following manner.
(A) Remove all wires from operator head.
With an Ohm meter, measure electrical resistance
between TP and TH terminals. If the resistance does
not fall within specification, replace valve. (See table 1).
Debris on seat of main valve. Replace valve.
Main seat blown out as a Replace valve.
result of exposing LPG gas
valve to unregulated line
pressure in excess of 15 PSI.