OM-TDH/TDHC 19
SYMPTOM
WHO
WHAT TO CHECK
X indicates items which must be performed by an authorized technician.
Spark is present but the pilot will
not light
Auth Service
Rep Only
a. That the pilot valve is securely connected to terminals.X
b. For 24 VAC at terminals PV and PV/MV. If 24V is not present, replace
the ignition control module.X
b. That gas pressure is at least 3.5” W.C.(8.7818 b).X
c. For gas at the pilot. If it is not flowing:
(1) Check the pilot gas line for kinks and obstructions.X
(2) Clean orifice, if necessary.X
(3) Check magnetic operator for pilot valve on gas valve. Repair or
replace as necessary.X
d. That the pilot spark gap is located in the pilot gas stream. If not,
adjust or replace the pilot burner.X
e. For drafts. Shield the pilot burner, if necessary.X
Pilot lights, but main burner will
not come on and spark does not
stay on
Auth Service
Rep Only
a. For 24 V between terminals PV and PV/MV. If 24V is not present,
replace the ignition control module.X
b. That gas pressure is at least 3.5” W.C.(8.7818 b).X
c. Electrical connections of the main valve to terminals, to a sure that
they are securely attached. Check magnetic operator for pilot valve on
gas valve. Repair or replace as necessary.X
Pilot lights, but main burner will
not come on, the spark stays on
Auth Service
Rep Only
a. Check for bad burner ground. If necessary, repair with high
temperature wire.X
b. Pilot burner ceramic insulator for cracks.X
c. That cable is not grounded out. If it is, correct the ground-out
condition or replace cable.X
d. For proper gas pressure.X
e. Clean pilot assembly, or replace if necessary.X
f. Tighten all mechanical and electrical connections.X
g. If the pilot flame is weak, increase pilot orifice size.X
h. Replace ignition control module.X
Main burner comes on but will
not stay on
Auth Service
Rep Only
a. Check burner ground for bad wire or connection. Replace if
necessary with high temperature wire.X
b. Check for low gas supply pressure. If necessary, replace ignition
control module.X
Troubleshooting
Summary of Contents for TDB 48A
Page 31: ...OM TDH TDHC 31 Wiring Diagram For Classic Control Models ...
Page 32: ...32 OM TDH TDHC Wiring Diagram For Advanced Control Models ...
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Page 35: ...OM TDH TDHC 35 ...
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