Rinnai RHFE-551FA Service Manual page 31

Troubleshooting
(FR) Flame Rod:
Flame rod - yellow wire = pin #26. Low fire current should be 1.3 to 2.0 micro amps (Fa). High fire current should
be 4 to 8 micro amps, depending on gas type being used.
NOTE: Improperly setup and/or converted units can soot and cause carbon to accumulate on flame rods. This
will cause hard lockouts. If carbon is found on the flame rod, remove and clean carbon from rod. Then
you will need to confirm manifold gas pressure, proper air dampers and ensure vent is clear. Also, check
for proper orifices.
(H , H and H ) Safety Circuit:
1 2 3
Check for continuity across pins 46 and 48 at terminal H on the PC board. If you have no continuity, this means
one of these switch/thermal fuses is open. Isolate the open switch or thermal fuse and replace the defective
component.
(OH - TH) Overheat Thermistor:
Check resistance reading across pins 9 and 10 at terminal A on the PC board. Proper readings should be 0.6 k
and 523 k. A reading below 0.6 k ohms indicates a short and a reading above 523k indicates an open circuit.
IMPORTANT INFORMATION CONCERNING HARD LOCKOUTS:
Other items that can cause lockouts are: Improperly converted units, spider webs in burner and
air intake of vent system, improperly sized gas lines, low gas pressures or pressure drops due to other appliances
on the gas system, improper ground or no ground at receptacle, supply regulators freezing up or defective,
voltage drops or bad receptacle, winds in excess of 30 to 40 MPH causing turbulence inside the vent terminal, etc.
Rinnai Direct Vent Service Manual
RHFE-431WTA
RHFE-556WTA
31