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Usnthedog's avatar
Usnthedog
Explorer
Jun 29, 2025

Tankless heater over heating

Furrion tankless water heater heats water to 144 degrees when set for 124 degrees.  I lowered setting to 115 degrees and it heated to 136 degrees.  We are traveling in the deep south and I thought it was due to the higher water temperature but I'm not sure.  Stange thing is if you only turn on the hot water the temp stays at 115 but if you turn on the cold water it heats to 136.  I tried to change the water flow valve at the heater but it won't move and is on max.  Do I have an issue??  I fear over heating the water tubes and having a blow out.  Is the issue in the heater control or the heater unit?  Since I'm on the road now I'm reluctant to get aggressive with control valave.     Thanks,  Jeff.

1 Reply

  • I wonder if it is trying to maintain the outlet temp instead of the temp of the hot water.  if it is accurate with just the hot water going then it seams to be that way.  I would just set the temp you want and only open the hot water.  I don't think you'll actually get anymore flow out of the rv water pumps with two taps open, or at least enough to make it worth it.