I'm in need of a plumber or technician who is a guru or at least a semi-expert in the world of tankless water heaters. Specifically, a Rheem tankless water heater that randomly goes on the fritz from time to time (usually during the hot part of the year) but that otherwise works fine.

The last guy we had out was extremely nice but admitted that he doesn't know much about the electronics and "just gets the manufacturer on the phone when the problem is occurring." Problem is, this is a sporadic issue that usually only happens in the evenings. So by the time we can finally get someone to come out, the problem has usually resolved itself.

So, if you know someone who is particularly good with these things, please send me their way. Thanks in advance!

I don't know of a specialist but I like Ed Phillips plumbing. He and I have talked through issues with my tankless and how to improve it.

For Rinnai, cascade tends to keep the motherboards in stock. That would be my guess for your fix - not a lot of field serviceable parts when it comes to the computer on those things.

If you have an electric tankless, you may have problems with low voltage. Otherwise, there is an issue with your mainboard.

If you have a propane tankless, it is probably a mainboard issue.

If he has a electric tankless, he needs a propane or natural gas tankless