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GNA-2538 R0
8.2. FENWAL-Related Issues
Input Polarity
If the system shuts down after the ignition trial period even though a spark is present and the gas valves are
open, measure the voltages at L1 and L2 with respect to ground. The voltage at terminal (L1) should be 120
VAC; the voltage at (L2) should be 0. (L2 is neutral). If the polarity is incorrect, check the fan and heater wiring.
Make sure they are wired correctly, and that a true neutral exists. A poor or nonexistent neutral will cause
erratic operation or prevent operation altogether.
Note
VAC refers to Volts Alternating Current.
Improper Grounding
If the system shuts down after the ignition trial period (even though a spark is present and the gas valves are
open) make sure the Fenwal module is properly grounded to the burner and that the burner itself is grounded.
It can be easily remedied by checking for continuity to ground.
High Resistance
Make sure all terminals make good contact. Clean all corroded contacts and replace any damaged wiring.
Valve Malfunction
Check the 1.5 amp fuse. If the fuse continues to blow, replace at least one of the solenoid valves (or its coil). If
the valve will not open even though there is a spark during the ignition trial, check the valve for an open coil or
broken wire. Use a voltage meter to make sure there is a minimum 110 VAC between (V1) and neutral.
Operation outside specifications could result in failure of the Fenwal product and other
equipment with potential for injury to people and property.
Igniter Malfunction
1. Check for a good ground between terminal B on the Fenwal module and the ground.
2. Make sure the spark plug gap is set at 0.07” (1.78 mm).
3. Check the orientation of the igniter. Spark gap should be pointed back at burner holes.
4. Replace the igniter if the porcelain is riddled with cracks.
5. Carbon buildup on the igniter electrode may cause arcing on the electrode closest to the igniter base.
Cleaning the igniter may cure the problem. If not, replace the igniter.
6. The igniter may arc to a location other than the electrode tip if the igniter shorts out against the heater. If
this happens, reposition the electrode. By moving it away from burner deflectors.
7. Check the connections on the Fenwal board.
Erratic Operation
Improper placement of the flame probe can lead to nuisance shutdowns. You may need to clean or reposition
the flame probe. To measure flame current, connect a DC microammeter in series between terminals FC+ and
FC- on the Fenwal Board. The meter should read 1 microamp or higher. Alternately, a voltmeter may be used to
measure DC voltage between FC+ and FC- terminals. Each micro-amp of flame current produces 1.0 VDC. For
example, 1 Volt DC equates to 1 microamp or higher while sensing a flame. A negative meter reading indicates
that the leads are reversed. Interchanging the meter leads will correct the polarity.
AXIAL FAN HEATER – LP AND NG-FIRED HEATER
