NatGas valve water exposure - effects?

[KTMBerg]

If a little water backs up into a gas valve, is it likely hosed?

My Rinnai R94LSi suffered a minor flood of water flowing through it for a short period of time when our sewer stopped up and water backed up through the ventstack condensate drain! (A check valve in addition to the gas trap would have been a good suggestion in the installation manual.)

It immediately threw a code 11 (no ignition) the next time the unit attempted to run.

When tearing it down to dry it out, I found the gas manifold full of H2O and some sitting in the outlet ports of the now-exposed dual port gas valve. I can presume some water crept into the valve(s) when the unit called for gas.

Thoroughly cleaned and dried everything (except the non-serviceable gas valve), reassembled, and all is good... so it seemed. Then it starts thowing a code 12 (flame failure) from time to time particularly when the gas flow is on its lowest setting to match low flow through the unit. Inspecting the flame in that condition, it's there but barely. Flame is just dandy on higher-demand settings. Flame sensor wires were checked and cleaned, with no change in results.

I can't find parts for Rinnai online so I guess I need to grovel to a dealer? Surely they hate DIYers.

Any feedback would be greatly appreciated!

[jadnashua]

Most gas valves should not be reused if they get immersed, and should be replaced. Most places don't like to sell gas parts direct to consumers for liability reasons, so your experience isn't particularly unusual. Whether it is actually safe, I cannot say. The owner's manual will probably have a statement about this situation, if not, call them to verify.