Bradford White IGI-180R-10 Service Manual page 43

VI - TROUBLESHOOTING
BEFORE CARRYING OUT CHECKS MARKED WITH A # SIGN, DISCONNECT THE POWER SUPPLY.
1) Is the water temperature thermistor operating normally ?
2) Is the change over solenoid (SV1) normal ?
(cont.)
Unable to adjust hot water temperature
a.
a.
b.
43
# Disconnect the connector B5, and measure the
resistance between the white wires, see below
for resistance readings.
Thermistor resistance valves:
59 ºF = 11.4 ~ 14 K Ω
86 ºF = 6.4 ~ 7.8 K Ω
113 ºF = 3.6 ~ 4.5 K Ω
140 ºF = 2.2 ~ 2.7 K Ω
221 ºF = 0.6 ~ 0.8 Ω
Normal: Proceed to check item 2 below.
Faulty: Replace the water temperature
thermistor.
(Service Procedure IGI-6, page 50)
# Disconnect the changeover solenoid (SV1)
connector, and measure resistance at the
solenoid terminals.
Normal: 1.7 ~ 2.1 K Ω
If normal, proceed to b.
Faulty: Replace the gas valve.
(Service Procedure IGI-9, page 52)
Measure the voltage at the changeover solenoid
(SV1) yellow ~ black wires.
Normal: 80 ~ 100 VDC
If normal, proceed to check item 3, on next
page.
Faulty: Replace the PCB unit.
(Service Procedure IGI-2, page 49)