Rinnai R94 PSi Error Code 10 and no error code

curbaniu

We own a small 25 unit mom and pop motel and have 4 Rinnai R94 PSi units. We have had error code 10, 11 and 12 in the past and our local propane guys have come out to clean the units and they worked fine for another year.

Earlier this month our units started error coding again (mostly 10 but sometimes 12) and we would have to turn them off/on to make it go away while we waited for the propane company to schedule us in. Sometimes turning it off/on would last hours or days and other times not even a few seconds before it would start beeping again. All four units
were randomly do this about a week before our big snow storm 3 wks ago when the power kept flickering for hours. After that only the main unit was error coding on us, the others were on and displaying the 120 (with the green light on next to the Priority button) but they weren't cycling the water or doing anything.

We thought it must be the PC Board, but our propane company has come out three times and can't figure it out (they are the ones who installed the units 9 years ago). We had a plumber come out and put a new thermostat on our holding tank as my husband noticed the old thermostat kept running but that hasn't fixed the problem. The main unit is still the only one running. It's like it's not communicating with the other three anymore.

The propane company is coming out tomorrow but any advice to have them check would be appreciated as running downstairs at 5am to turn the unit off/on to get the hot water flowing again gets a little cold in this winter weather!

Thank you!