Tankless heater alarm

[JVfromGrnBay]

Several times recently I have heard an alarm from the tankless water heater control panel while I am showering. It is a series of 3 short beeps, repeating approx 7 times. It always stops before I finish my shower so I cannot see any warning light when I check the panel. Any ideas on what this alarm is indicating? 2021 GT 25 FBT

[Bcc75]

Do you turn the water off at the shower head and/ or turn the water almost off?
Either way you would have a minimal flow of water. The tankless heater has to detect a certain amount of flow in order to fire. If not enough flow is detected it will throw a ‘low flow’ alarm. I had this happen while showering and I had the water almost off. My wife was in the bathroom and saw the error code on the panel and I looked it up later. Sure enough that’s what it was.

[JVfromGrnBay]

Each time the alarm has sounded the shower has been at full flow. I typically take a "navy shower" in the trailer and the alarm has been in the rinse phase but yesterday it also sounded briefly in the initial soaping phase.

[mewmmw]

Had the same symptoms tonight while both my wife and then I showered. No error code showing on hot water panel

[mewmmw]

Adding on to this we kept having to turn the water down as the temperature kept getting hotter than normal. I also noticed this am the rv shower seemed hotter so I’m wondering if the water out of the hose bib is too hot?

[Merlintiaga]

Do you have a shower miser installed? If yes, is the return connected to the input side of the pump or the fresh water fill hose? Connecting the return from the shower miser to the input side of the pump will cause an over-heat alarm on the water heater. The return needs to be connected to the fresh water fill hose.

[mewmmw]

No miser installed that I’m aware of. This problem only started occurring after we entered the inferno of Texas recently. Last night I monitored the gauge in the bathroom while my wife showered and the gauge at one point shot up to 138 along w the 3 beep alarm and the E3 code displayed.