Bradford White IGI-180R-10N - Manual (Page 44)

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a. # Disconnect the modulating valve festoon C2
terminals and measure the resistance at the terminals.
Normal: 67 ~ 81 Ω
If normal, check b.
Faulty: Replace gas valve.
(Service Procedure IGI-9, page 52)
b. Re-connect terminal C2 and measure voltage
across the pink ~ pink wires when the unit is
firing.
Normal: 2 ~ 15 VDC
If normal, check c below.
Faulty: Replace the PCB unit.
(Service Procedure IGI-2, page 49)
c. Investigate the change in the manifold gas
pressure, when the remote control pre-set
temperature is altered from 96 ~ 140 ºF.
Normal: If the manifold pressure changes,
proceed to check item 4 below. DO NOT
adjust manifold pressures.
Faulty: Replace gas valve.
(Service Procedure IGI-9, page 52)
a. # Disconnect connector B2 and measure the
resistance of the water flow servo, red ~ blue wires.
Normal: 22 ~ 26 Ω
If normal, proceed to b.
Faulty: Replace the water flow servo and sensor.
(Service Procedure IGI-2, page 49)
b. Disconnect connector B2 , and measure the voltage on
the PCB unit side, were the orange (+), and/or grey or
black (-) wires connect to the board.
Normal: 3.3 ~ 4.5 VDC
If normal, proceed to c.
Faulty: Replace the PCB unit.
(Service Procedure IGI-2, page 49)
c. With connector B
2
, connected (do not turn water
ON … wait for the water flow servo to return to
fully open), measure the voltage at the brown ~
grey wires.
Normal: 4 ~ 6 VDC vent limiter OFF
Faulty: Replace the water flow servo and
sensor. (Service Procedure IGI-2, page 49)
d. With connector B2 , connected (do not turn
water ON… wait for the water flow servo to
return to fully open), measure the voltage at the
yellow ~ grey wires.
Normal: Less than 0.5 VDC when unit is set at
120 °F and there is no water flowing through the unit.
Faulty: Replace water flow servo and sensor.
(Service Procedure IGI-2, page 49)
3) Is the modulating valve operating normally ? Error code 52
4) Is the water flow servo normal ?
BEFORE CARRYING OUT CHECKS MARKED WITH A # SIGN, DISCONNECT THE POWER SUPPLY.