Verify Voltage

Are you handy with a multimeter? Both AC and DC circuits are used in Noritz units. The Technical Data Sheet taped to the inside front cover of the units will summarize the voltage checkpoints for all the components, amp draws from the flame rod assemblies and resistances on the gas valve solenoids and hi limit switches

AC Checkpoints

power supply to circuit board = 120VAC

igniter spark = 120VAC

DC Checkpoints

remote controller = 15VDC

quick connect = 15VDC

water control valves = variable 1-15VDC

flow sensor = 15VDC

gas valve = 90-120VDC

Amp Checkpoints

flame rod rectification > 1 micro amp (10^-6) when flame is present, < 0.45 micro amps when no flame is detected

Resistance Checkpoints

gas valves = 1220-1500 ohms

high limit switches < 1 ohm

thermistor resistance < 1 ohm