Greenheck TSU Direct Gas Manual (456857) - Manual (Page 7)

Trouble Shooting
The following is a cause and correction list for common problems with these units. Also included in the unit owners
packet are the Maxitrol Systems owner’s manual plus the Flame Safeguard owner’s manual. The sequence of operation
should be used to help determine where the problems could be when trouble shooting the unit.
Heater
Symptom Possible Cause Corrective Action
Blower runs but Gas is not on Turn gas on
heater will not operate
Heater is not getting power Check switch and wiring
Gas piping is not purged of air Purge line
Inlet clogged Clear inlet of unit
Filter(s) clogged Clean or replace filters
Ductwork clogged Check ductwork for obstructions
Registers in building closed Open registers
Airflow pickups clogged or Unclog pickups
tubing crimped Straighten or replace tubing
Blower rotating in the Reverse blower rotation
wrong direction
Inlet damper closed Open damper
or not fully open
Bad airflow sensing switch Replace
Note: Do not replace or adjust airflow switch
without determining burner air pressure
differential, Step 2 in the system startup.
Flame safeguard is not A. Check heater main voltage
getting power B. Check high limit switch (requires manual reset)
C. Check High/Low Gas Switch
D. Check inlet air sensor setting (if supplied)
E. Check wiring
F. Check summer/winter switch in gas section
Flame safeguard is getting A. Reset manual switch on cover of flame
power but will not operate safeguard
B. Check airflow and switch
C. Check purge card
Inlet clogged with ice or snow Check for building or unit exhaust near intake
Moist air can clog filter with snow and frost
Unit not grounded or The flame safeguard will not operate if unit is
improperly grounded not grounded
Blower Runs, heater tries Air in pilot line Cycle unit to purge air
to light - no visible pilot
Spark rod and flame
Check wires to be sure they are correct
rod wires crossed
Bad connections to spark Check all wire connections from flame safeguard
generator and to spark plug
Spark plug gap not set Adjust spark plug gap to .062"
Cracked porcelain Replace spark plug
Dirty or corroded spark plug Clean and remove any matter from the spark
plug or porcelain or replace with AC or equivalent
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