Rinnai ByPass Servo Troubleshooting Manual page 9

11. WARNING: Turn off the electrical, gas and water supply before performing this inspection. Remove
the igniter and flame rod assemblies and inspect them for carbon or a white substance build-up. Clean
both components before re-installing them. If you removed just the igniter and flame rod assemblies,
make sure you have a new flame rod/igniter gasket before removing these components. This gasket
MUST be replaced if the seal is broken.
12. 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. Next; remove the burner manifold and inspect the
orifices on the back side of this manifold for clogged or blocked orifices. Proceed with removing the
burner assembly and inspect the chamber for insects or other debris. Clean out all debris found in the
burner and air chambers. Also inspect the copper fins in heat exchanger for a build-up between the fins.
Build-up or blockage between the heat exchanger fins will cause air flow restrictions, which will lead to
code 10's. If build up is present, you will need an air compressor capable of delivering 120 psi of
compressed air to blow out the burner and heat exchanger fins. If unable to clean the heat exchanger
with compressed air, replace the heat exchanger. CAUTION: Always wear safety glasses and a mask
when blowing out the burner.
13. 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.
14. 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.
15. Verify that proper venting materials were used in this installation. They must use the correct venting
material for class III appliances approved by Rinnai. See Rinnai venting instructions for details.
16. Verify proper altitude settings, see high altitude gas pressure setting procedure for dip switch and
manifold gas pressure settings.
17. 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.
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