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Code 12 Troubleshooting Procedure
Flame Failure
NOTE; before troubleshooting your code 12 first determine what type code 12 is present. Look into the
view window while the appliance is going through the ignition cycle to see if you ever see a visible flame.
The reason for this is; there are two types of code 12's. The most common code 12 is called a flame
failure, meaning the appliance did sense a flame at one point. In other words you could see a visible
flame in the burner box during the ignition cycle and/or during operation. The other is called an
immediate code 12 and/or no flame was ever noted in the burner box. If you note a flame even for a
few seconds follow steps below. If no flame was ever noted proceed to the last item listed in these
instructions called, "Immediate code 12 or no flame visible in burner box".
Often it is difficult to distinguish between a gas code 12 or and electrical code 12. The easiest way to do
this is to turn off the gas and then try firing the unit. It should go to a code 11 at that point. If it goes
onto code 12 you have an electrical short in a component or wiring harness.
WARNING:
You must be qualified to service gas systems before proceeding with the following items
listed below.
1. Verify proper inlet gas pressures are being fed to appliance. Check appliance rating plate for proper
pressures. This plate or label is located on the side of each unit. The minimum listed inlet pressure MUST
be maintained with all gas appliances at the location firing on high fire.
2. If you note improper inlet gas pressures check to see if the gas system was properly sized. If sized
properly you should see no more than a 0.3 inch pressure drop on natural gas with all gas appliances in
the building firing on high fire. The allowable pressure drop for propane is 0.5 inches of water column.
This pressure drop is based on the International Plumbing Code when operating on gas pressures up to
14" inches W.C. with black iron piping. There are a number of approved gas piping system out there,
make sure you refer to the manufacture's or International Plumbing Code book for pressure drops on
gas piping and pressures you are using for proper pressure drops allowed. If pressure drop excesses that
mentioned above for black iron gas systems, your system could be undersized, please recheck sizing.
The issue could be in any of the following items; the gas system, gas piping, regulator, tank, utility
supply, dirt or debris in gas system components, etc. Have the gas system checked by a professional gas
technical or master plumber that deals with gas system sizing. Refer to the International Plumbing Code
Book for proper gas system sizing for gas type, piping and pressures being used at this location.
3. Verify manifold gas pressures. You will need the gas pressure setting procedure for the model number
appliance you are working on. This information is normally found in a plastic holder on the back side of
the front panel. If procedure is not available contact Rinnai tech services for data. Verify correct dip
switch settings before adjusting/checking gas pressures. Dip switch settings can be found in the gas
pressure setting procedure. If in altitudes above two thousand foot in elevation refer to high altitude
settings and pressures. Next; connect your manometer to the gas valve test port. Fire the unit up
ensuring you have at least three gpm's of flow through the water heater. You can use the unit's key pad
to check your flow rate to verify three plus gpm's. Then; place the unit into forced low fire and follow
the gas pressure setting procedure to adjust the low fire gas pressure. Next place the unit into forced
