Rinnai ByPass Servo Troubleshooting Manual page 12

high fire per gas pressure setting procedure. Adjust high fire pressure per instructions. Improper
manifold gas pressures can lead to code 12's.
CAUTION: Verify all vent connections are properly seated per manufacturer's venting instructions.
4. Inspect vent system for loose joints, improper fittings, failure to meet proper clearances around vent
terminal outside building. See venting instructions for clearance specifications. Failure to meet vent
terminal clearances can lead to recirculation of combustion gases causing incomplete combustion which
will lead to code 12. In addition; ensure vent length is within specifications and dip switch for vent
lengths has been properly set.
5. Ensure the proper venting materials were used in this installation. You must use concentric venting
material for class III appliances approved by Rinnai. See Rinnai venting instructions for details. Verify
venting component at unit's vent connection is fully engaged into top of water heater. Separate
connection to check for proper connection. You can mark the white vent material at the stainless steel
connection before pulling it apart to check depth once separated. Failure to have this joint fully engaged
will results in code 12's within ten seconds of the unit firing.
6. Make sure the flame rod is tight in its mounting bracket. You should not be able to move it with your
finger if the gasket is intact. If you remove the flame rod it is very important to note the orientation
before removal. After removing it, clean it before re-installing. Re-install the flame rod in the same
orientation as it was before removal. You MUST replace the flame rod/igniter gasket before reassembly.
Note; a loose flame rod is called a floating flame rod and will result in code 12's. Flame rods should
never have to be replaced unless the white ceramic is cracked or broken or the flame rod is damaged.
8. Inspect flame rod wires looking for loose or damaged wires or connectors at the flame rod and PC
board.
9. Inspect flame rod silicone protective sleeve for cracks or heat damage. If cracked or has heat damage
the spark could possibly seek a grounding source other than the intended target though the igniter,
replace the sleeve.
10. A properly grounded circuit is critical. Check to ensure all ground connections are intact, free of
corrosion, tight at each joint or connection and the polarity of the circuit is correct. If unsure contact a
Licensed Electrician to inspect and/or correct any issue with the circuit.
WARNING: Turn off the electrical, gas and water supply to the water heater on the following series
product to perform this task, VA, VB, VC and KA units.
11. Pull the unit's burner and inspect for debris and/or condensate around the burner located at flame
rod position. Clean all burners using 120 psi of compressed air. Blow out combustion chamber and
copper fins in heat changer while inside the burner box. If you are unable to clean out the debris
between the copper fins in the heat exchanger, replace heat exchanger. Note the copper surface where
the burner box and heat exchanger meet. If that surface appears black from heat stress that's a good
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