Greenheck TSU Direct Gas Manual (456857) - Manual (Page 8)

8
Heater
Symptom Possible Cause Corrective Action
Blower runs, heater tries Cracked flame rod Porcelain can be cracked. Replace
to light with visible spark, flame rod.
and possibly pilot but
shuts down prior to
No gas to pilot A. Check gas pressure
main fire. B. Check pilot solenoid valve for
restrictions
C. Check pilot regulator for restrictions
D. Check for bend in aluminum pilot line,
repair or replace
Check for ground A. Unit should be well grounded
B. Flame safeguard has a grounding
screw in it, check to see if it is
grounded. Pilot will not work if unit is
not grounded.
Dirty flame rod Clean flame rod with emery cloth and
wipe porcelain clean.
Flame rod is grounded out Check that flame rod is not touching
burner or that foreign debris is not
grounding out unit. Clean or adjust.
Blower runs, High limit switch not
High limit should be set to 130°F.
high limit trips out set correctly
Modulation device is not Check modulation system and see
modulating owners manuals for repair.
Blower runs, flame High gas pressure not set properly See startup instructions for
safeguard goes out on setting high fire
safety after operating
or unit cycles on and off
Pilot regulator not set properly Pilot is too large causing flame to go
past flame rod. Turn down gas pressure
Airflow too low or marginal for unit. A. Adjust unit's CFMs to increase SP
Unit heats, lowering airflow loss across burner
causing switch to open B. Adjust baffles across burner to
increase SP
Microamps not steady with pilot on A. Check wiring for spark rod and
flame rod
B. Check for cracks in porcelain on
flame rod. If present, replace
C. Soot buildup on flame rod
If present clean rod
Blower runs, unit heats, Output temperature not set properly See startup section for proper setting
Output air not warm
enough.
Main regulator not set properly See setup section for setting high
fire on main regulator
Clogged vent orifice on regulator Clean or replace vent
Supply pipe too small Recheck pipe size going to unit and
repipe with larger pipe if necessary
Discharge bulb not sensing Check placement, should be in
discharge air blower discharge
Maxitrol System Refer to Maxitrol manuals,
not functioning properly make adjustments as manuals suggest
Supply pressure too low Contact utility company