Rinnai C42e - Page 11

Rinnai Water Heater Service Manual 11 100000098 Rev B
Electrical Diagnostic Points
Wire Color Voltage Resistance Connector No. Pin No.’s
Thermal Fuse / Overheat Switch
Red - Red 12 VDC below 1 ohm B, C 6 (B) ~ 1 (C)
Flame Rod
Place one lead of the meter to the flame rod and the other to ground. Flame rod to ground should
read 1 mega ohm with unit not running. With the unit running, 5-150 VAC should be read. If voltage
range is incorrect then replace PC board. Set the meter to the μ amp scale and series the meter in
line with the flame rod. Proper flame circuit should read 1 micro-amp or greater. If micro-amp range
is incorrect then clean flame rod; replace flame rod if cleaning fails.
Thermistors
Check all thermistors by inserting meter leads into each end of the thermistor plug. Set the meter to
the 20 K ohm scale and read resistance. Applying heat to the thermistor bulb should decrease the
resistance. Applying ice to the thermistor bulb should increase the resistance. Typical resistance
values are: 11.4-14 K ohm for 59°F; 6.4-7.8 K ohm for 86°F; 3.6-4.5 K ohm for 113°F; 2.2-2.7 K ohm
for 140°F; 0.6-0.8 K ohm for 221°F
Outgoing Water Thermistor
White - White see above B4 1 ~ 2
Heat Exchanger Temperature Thermistor
White - White see above B5 1 ~ 2
Surge Protector
Blue - Brown 108 - 132 VAC N/A F4 1 ~ 2
Blue - Brown 108 - 132 VAC N/A F3 1 ~ 3
With the power off, check the continuity through the surge protector. Check by placing one meter
lead on the top pin #1 and bottom pin #2. Check by placing one meter lead on the top pin #3 and
bottom pin #1. If there is continuity across both sets of points, then the surge protector is good.
Controller
Terminals D1
10 - 13 VDC
digital
1.5 - 1.9 K ohms D 1 ~ 3
Frost Protection
There are electrical heating elements mounted at different points to protect the water heater from
freezing.
heaters located on the hot water outlet line 26 - 30 ohms
heater located on heat exchanger piping 81 - 86 ohms
heater located on water flow sensor 16 - 19 ohms
Amp fuses
There are two inline 3 amp glass fuses. Remove the fuse and check continuity through it. If there is
continuity then the fuse is good.
R/C42e, R/C53e