Rinnai HE Series How To Use Manual page 161

10. Look into view window on appliance to see if you ever see a flame in the burner box while the unit is
going through the ignition cycle. If you do that indicates an issue in the flame rectification circuit. This
could be a buildup of carbon or a white substance on flame rod, bad connection at flame rod, loose or
damaged flame rod, bad PC board, gas valve or low inlet gas pressures. Before replacing the PC board or
gas valve continue troubleshooting the steps below.
11. Remove igniter and flame rod and inspect them for carbon or a white substance build‐up. Clean both
the igniter and flame rod before reinstalling. In addition inspect the burners under the igniter for
condensate build‐up or debris. Blow out burners and burner box with 120 psi of air. If you remove just
the igniter and flame rod assemblies, make sure you have a new flame rod/igniter gasket. This gasket
MUST be replaced if this seal is broken. While inside the burner box look up between the copper fins
inside the heat exchanger for debris and/or blockage. Blow out fins, if unable to clean out fins inside
combustion box replace heat exchanger.
12. 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.
13. Inspect vent system for loose joints, improper fittings, failure to meet 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 carbon build up on flame rod. In addition; ensure vent length is within specifications and dip
switch for vent lengths has been properly set.
14. Verify installer used the proper venting materials for the unit at your location. They must use the
correct venting material for class III appliances approved by Rinnai. See Rinnai venting instructions for
details.
15. Verify proper altitude settings, see high altitude gas pressure setting procedure for dip switch and
manifold gas pressure settings.
16. On internal units inspect the plastic tube running from the bottom of the combustion chamber to
the gas valve. If you find moisture in that tube, replace the gas valve. Also inspect the vent system to see
where the condensate/moisture is coming from. The burner and heat exchanger fins should be
inspected for excessive corrosion also. Signs of moisture could be a result of an improper venting or a
leak inside the heat exchange.
17. Verify installer used the condensate drain tap as recommended by Rinnai on the vent terminal
connection at the top of the water heater, non‐condensing product. If the condensate drain line is not
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