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Rinnai tankless shutting off.

Happy? Sunday. I've had a problem with a 7 months old Rinnai tankless for about 4 days now. Not having any luck with any online troubleshooting. Hot water will start and flow for just under 6 minutes, then the unit itself shuts off completely. No error codes come thru. Cleaned the water inlet, not too bad. Plugged and unplugged. Plumber who installed will not return any calls. Any advice would be appreciated.


  • Leon82Leon82 Posts: 616Member
    How much would you say is flowrate of what you are using.

    If it is low near the activation rate there may be some scale which is bringing the flow too low to turn the unit on
  • hotrockpolockhotrockpolock Posts: 3Member
    Is that something we or a plumber needs to look at?
  • Leon82Leon82 Posts: 616Member
    Open a couple faucets and see if it stays on. This should guarantee you will be over the activation rate.

    Maintenance should be done yearly descaling with vinegar or a flowaid type product. More often for higher mineral content water

    Tankless turn on around.5 to ,75 gallon per minute. If you are on the borderline it may start and stop.
  • hotrockpolockhotrockpolock Posts: 3Member
    Thanks for your help. Water only stays flowing hot for approximately 4-5.5 minutes. Then goes entirely cold. Hot only starts back up after all flow is turned off for about 5 minutes, then same routine. Manufacturer help request in order, due to only being 7 month old?
  • Leon82Leon82 Posts: 616Member
    If it's not throwing a code it's hard to diagnose.

    Is the condensate drain clear?
  • DZoroDZoro Posts: 768Member
    What faucet are you running? Bath sink, bath tub, kit? What model?
  • lchmblchmb Posts: 2,932Member
    Does it do it every time? Have you cleaned the inlet screen to the unit? Do you have a water filter that needs to be cleaned? wonder if a flow servo is failing. Need to test what the unit is seeing for flow at the time it has stopped heating. Without shutting off the water..
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