Rinnai RHFE-551FA Service Manual page 33

Troubleshooting
(PS) Pressure switch:
White - Ground
Check from both white to ground to ensure circuit is complete.
In order to eliminate this switch as a cause of failure, shut the power off to the unit and jump out this
switch. Resart unit. If it functions, remove jumper, and replace air pressure switch.
(RT) Room temperature control:
To check the slide thermostat, set your meter to the 200k ohm scale. By reading across the white and
black wires you should have an ohm reading from 0 to 30k ohms from low to high, after unplugging pin #9
and 10 from PCB.
(TH) Thermistor:
Check thermistor by inserting meter leads into each end of thermistor plug. Set your meter to the 200k
scale and read resistance. You should be able to apply heat to the thermistor bulb and see resistance
decrease. Then apply some ice to the thermistor and the resistance should increase. Pin # 6 and 7.
EXAMPLES:
(FR1, FR2, and FR3) Flame Rods:
FR2 and FR3 are high fire flame rods = the left hand rod (FR3) is a white wire with a blue tracer and the
right hand rod (FR2) is a white wire with a red tracer. Flame current through these rods should range
from 4 to 8 micro amps depending on gas type being used. FR1 low fire flame rod = white wire with yellow
tracer located on the front center of unit next to the electrode. Low fire flame current should be 1.2 to 2.0
micro amps. The micro symbol on your meter will look like this µ.
Improperly setup and /or converted units can soot and cause hard lockouts. If carbon is found on any
one flame rod, remove all three rods and clean carbon from them. Then you need to confirm your
manifold gas pressure and air rod settings. Also, 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:
Check for continuity reading from pin #22 blue wire to pin# 27 orange wire. If you do not read continuity through
this circuit, locate defective switch and replace that component.
(MS) Main Switch:
In the off position you should read continuity from the brown wire to the blue wire. In the on position you should
read continuity from the brown wire to the red wire. If not, replace main switch.
41 °F = 91 k ohms
50 °F = 65 k ohms
68 °F = 39 k ohms
86 °F = 23 k ohms
Rinnai Direct Vent Service Manual
9 - 12 VDC
RHFE-1001FA
n/a 4 - 5
33