Rinnai RHFE-551FA Service Manual page 72

Troubleshooting
(FM)
Read voltage across:
Black-Red
* Be sure to check for obstructions to blades. Check the capacitor before replacing motor.
(PS) Pressure Sensor:
Note: Ensure clear and black hose from pressure switch to blower air chamber is not blocked or
crimped with any obstructions including spider webs.
(TH) Room Thermistor:
Check thermistor by inserting meter leads into each end of thermistor plug. Set your meter to the
200 KΩ scale. Apply heat to the thermistor bulb and the resistance should decrease. Apply cold
and the resistance should increase. Examples of readings:
41ºF=91KΩ
(FR1, FR2, FR3) Flame Rod
FR1 and FR2 are high fire flame rods. The left hand rod (FR1) is a blue wire and the right hand
rod (FR2) is a red wire. Flame current through these rods should range from 4 to 8 micro amps (µ
amps) depending on gas type being used. FR3 fire flame rod is the yellow wire located on the
front center of the unit next to the electrode. Low fire flame current should be 1.2 to 2.0 micro
amps (µ amps).
Improperly setup and /or converted units can soot and cause hard lockouts. If carbon is found on the
flame rod, clean the carbon from it. Confirm that your manifold differential gas pressure on Hi fire and Lo
fire is correct. Insure primary and secondary air dampers are correct. Check to ensure proper orifices
were placed in the unit..
IMPORTANT INFORMATION CONCERNING HARD LOCKOUTS:
Other items that can cause hard lockouts are: improper sized gas lines, low gas pressures or pressure drops due
to other appliances on the gas system, spider webs in the burner and air intake of vent system, improper ground
or no ground at receptacle, supply regulators freezing up or defective, voltage drops or bad receptacles, winds in
excess of 40 mph causing turbulence inside the vent terminal, etc.
(OHS1, OHS2, TF1, TF2) Safety Circuit Check: CN8
Check for continuity reading from pin #1 white wire to pin #5 blue wire. If you do not read continuity through this
circuit, locate defective switch and replace that component. Determine what caused overheat condition.
(MS) Main Switch: CN11
Disconnect CN11 from PCB, being careful not to break wires. Read Blue to Blue, pin #9 and 10 on 40KΩ . When
ON/OFF is in the ON position, you should read 10--18KΩ. When released, you should read open or 0 Ω
Wiring harness, connectors, and fuses should be checked if all above readings are normal.
72
Voltage Potential
40-105 VAC
Electronic
50ºF=65KΩ 68ºF=39KΩ
Rinnai Direct Vent Service Manual
Read resistance
25-50 Ω
0.31 in (8.0 mm) WC
ON
86ºF=23KΩ
RHFE-1004FA
RHFE-1004RFA
RHFE-1004FTA
Pin Numbers
1-2
0.11 in (2.8 mm) WC
OFF