4
-BURNER IGNITES BUT THEN SHUTS DOWN
A-
Check flame current coming back to gas primary.
Flame current is the current that passes through the flame from the sensor to ground. The minimum flame
current necessary to keep the system from lockout is 1 microamp. To measure flame current, connect an
analog DC microammeter to the FC terminals (beside LED light). Meter should read 1 microamp or higher.
If meter reads below “0” on scale, meter leads are reversed. Disconnect power and reconnect meter leads
for proper polarity.
B- If flame current measures below 1 microamp, replace gas primary control
C- If no flame current measured, remove electrode assembly. Check continuity on flame rod wire.
Inspect flame rod for chips or cracks. Clean if necessary. Check and clean nozzle. Ensure all connections
are tight.
D- Supply gas pressure to unit must be the proper pressure. (Refer to manual) If wrong size line is
used to correspond with length, you may have to adjust to ensure correct supply pressure at unit.
E-Check polarity, ensure no AC voltage on terminal 2. Voltage supply must be consistent 108-132
volts.
F- If you are running more than one unit off of a single gas source and one unit is shutting down, be
sure size of hose is correct for the BTU’s and the length of the hose. Check at test port on elbow to ensure
proper and constant pressure to burner.
5-MAIN SUPPLY MOTOR DOES NOT COME ON, UNIT SHUTS DOWN ON HIGH LIMIT
A- Check temperature feeler, make sure it is in properly.
B- Jumper out fan switch to test motor. If you have voltage to motor and still does not start replace
motor. Check line voltage to ensure proper voltage. Also check amp draw on motor, motor may be running
too hot and not running due to thermal overload being tripped.
C- Replace fan switch if you have power on one side after unit heating up it does not make.
D- Replace high limit as it may be tripping too soon and not giving fan switch time to engage.
Connect D.C. Micro amp multimeter probes to FC pins controller ( beside LED light). You should
receive a reading between 3.5-5.5 microamp (fluctuating 10%) during the time it fires. If reading is lower,
check flame rod and wire as per trouble shooting instructions. Disconnect orange MVI wire f rom controller.
Shut off gas and with AC voltage tester, check between 24v ground side o f transformer and MVI terminal for
voltage during TFI. Reading should be steady 24v. AC.
E- Make sure fan switch is at the correct temperature for conditions. See page 18 for settings.
6-IF THE UNIT DOES NOT RUN SMOOTHLY AND QUIETLY
A Check to ensure proper gas supply pressure and proper manifold pressure.
B Adjust the air setting on the adjustable damper connection.
9
Summary of Contents for IDH350QR LP/NG
Page 12: ...10...
