Rinnai Tankless Water Heater Troubleshooting

Rinnai Tankless Water Heater Troubleshooting

I need your advice on Rinnai tankless water heater troubleshooting.

I’m assuming you paid the gas bill and don’t have thermostat wars over the tankless hot water heater.

That does not come up because you can simply turn the knob to get more cold water in the mix, except we are not getting much hot water.

They have problems with sediment build up, and even though they have scale control systems, you can get error codes LC zero through nine for scale build up inside the heat exchanger.

The error codes I’ve seen are only numeric.

Rinnai’s code 3 error means there was a power interruption during operation, like when you’re filling a bath tub.

What do I do about it?

The advice per the manual is turn off all the hot water, hit the on off button on the temperature controller twice, and you’ve reset it. If you’ve got brown-outs in your area, you may need to do this a couple times.

I do not know if that is better or worse than having to go down into a cold dark basement to reset the furnace.

You can get the code 3 error with Rinnai units if there’s an electrical disruption, like a circuit breaker tripped or fuse burned out. Again, fix it by hitting the on off button on the controller twice, after flipping the circuit breaker or replacing the fuse.

I cannot tell the 3 from a 5 on that unit.

If you have a code 5, the manual says to turn off power to it, turn power back on, fire it up, and if you still get the error, replace the bypass valve.

What is error code 10?

The error code 10 means the venting system has a blockage. That could be at either the intake or the exhaust.

It might have been an 11.

Code 11 means there is no ignition or the unit thinks there is no ignition. You can test the ignition to see if that sparks.

And replace it if it does not.

Code 16 means it is too hot and shuts down.

Code 14 is the same thing, well, except the manual says that’s for high temperature.

You could have a loose connection, or you could have all the same problems with a rusted burner or carbonization on it that you would see with the house furnace burner.

And even more water around it that could leak and rust things out or short out electrical connections.

Error code 12 in Rinnai systems means there’s no flame, but it can be due to a flame sensor or controller malfunction as well as burner issues.

Do I replace the flame sensor?

Power cycle it first, see if it comes up, then start looking for electrical and mechanical causes. Or a plumber’s number.