Rinnai Tankless Water Heater only putting out warm water

michaelnadel

Hi
I have a Rinnai tankless water heater (R94LSi) that has been working perfectly for 10 years. Each year I flush the system with white vinegar as instructed in the manual. After doing some unrelated plumbing, I turned the water back on and now the Rinnai is only putting out warm water. I suspected sediment might be blocking something so I flushed out the system for several hours with vinegar. It is still only putting out warm water. The water flow through the heater is very strong. It sounds like it is running normally but then slows down as if running at a slower speed. I'd be surprised if it decided to break at the exact time that I was doing my plumbing work. Could sediment fool the flow sensor? Would that cause this problem or could it be something else? There aren't any error codes being displayed.
Thank you for your help,
Mike

delta T

check your air inlet to make sure it isn't clogged with a wasp nest or something similar, pull the fan and check the fan blades for obstructions, and check the air inlet outside. I was tracing a similar issue recently on a c51 and it turned out the fan was full of dead wasps. Did you pull the water filter out and check it for an obstruction?

michaelnadel

The air intake both inside and outside are clear. The fan is clean as well as the water filter at the intake.
Thanks for your response

michaelnadel

I have also removed and inspected the flow turbine as per technical bulletin #105. No help.

michaelnadel

I did find 2 small chips on the bottom of the flow turbine. Is it possible that this could be the cause?

SuperTech

> @michaelnadel said:
> I did find 2 small chips on the bottom of the flow turbine. Is it possible that this could be the cause?

It's possible, seeing that the flow of water is what turns the burner on.

Slimpickins

Sounds like you have a crossover connection in your plumbing. If you shut off the supply ball valve on the cold feed to unit and open the relief valve and have pressure and flow, that's your problem.

FFernandez

Hello Slimpickins, a while ago you mention to a person complaining about only having warm water on his rinnai tankless water heater after cleaning or working on the plumbing. and you mention a cross over plumbing what you mean by that cause i having same issued after doing the flush on my tank.
i did close the supply line and open the pressure valve and i do have a flow of water and pressure.
thank you
hope you can help me with this situation.
F.Fernandez

Slimpickins

If you close the valve feeding the unit on cold side and you have pressure by popping the relief valve, you definitely have a cross in your plumbing. Maybe you don't have your valves in the right position under the unit after you flushed it.

To verify that you have a cross. Make sure you have the cold supply valve open, then close the hot side valve off. Either put a hose on the hot side ball valve and run or let it run out the relief valve if you can. If the water it hot, you have a cross inside on the plumbing somewhere. It could be a few things, if you have a recir pump, you may have a bad check valve.