Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Tankless water heater water intermitently turns cold

I have Renai R85 tankless water heater. The issue of hot water suddenly becoming cold for a minute or two before becoming hot again occurs only in the Kitchen faucet. This does not occur anywhere else like in bathrooms etc.

I have flushed the unit and increased water temp to 130 which helped a little but the issue has not completely resolved. There are no error codes. I noticed while hot water was on the burner in the unit stopped momentarily (and water started to get cold in kitchen). It began to fire again a minute or so later. I am not sure some sensor needs to be replaced or something else might be worng. Any suggestions? Much appreciated

Comments

  • mikeg2015
    mikeg2015 Member Posts: 1,187
    Minimum firing rate issue? Maybe flow rate was below minimum? Flow sensor could be going bad. IS the water temp steady? Does it do it at high flow rates?
  • HVACNUT
    HVACNUT Member Posts: 4,856
    If the problem is only from the kitchen faucet it stands to reason that the issue is with the faucet. Anti scald, single lever, or the piping to it.
    How's the pressure at the kitchen faucet? Try cleaning the screen thingy (aerator?) if it has one.
  • SuperTech
    SuperTech Member Posts: 1,854
    I'm not familiar with that unit, but based on your description it sounds like a possible flow issue. Is there any reason why the flow would be different for this faucet? I'd check any visible piping and compare sizes, number of elbows against the working faucets. Something is different causing the tankless to respond differently. How long has this been happening? Has this always happened with this unit? Any pictures of the equipment and piping could help us too.
  • Leon82
    Leon82 Member Posts: 684
    Check the faucet strainer. It may be a little clogged. There may be an orange in there too can remove for more flow
  • SuperTech
    SuperTech Member Posts: 1,854
    > @Leon82 said:
    > Check the faucet strainer. It may be a little clogged. There may be an orange in there too can remove for more flow

    How would an orange get in there? Thats crazy talk. I would definitely check the strainer, that's easy enough. See if it still happens with the strainer removed.
  • Canucker
    Canucker Member Posts: 717
    Or spellcheck guessed orange instead of orifice
    You can have it good, fast or cheap. Pick two
  • Leon82
    Leon82 Member Posts: 684
    I meant to write oring
    Canucker
  • SuperTech
    SuperTech Member Posts: 1,854
    > @Leon82 said:
    > I meant to write oring

    I thought that was it, crazy talk was the more interesting explanation. How would an O ring restrict the flow? I don't do plumbing much, I'm an HVAC technician. Maybe this is something I haven't seen in my own faucets
  • Leon82
    Leon82 Member Posts: 684
    > @SuperTech said:
    > > @Leon82 said:
    > > I meant to write oring
    >
    > I thought that was it, crazy talk was the more interesting explanation. How would an O ring restrict the flow? I don't do plumbing much, I'm an HVAC technician. Maybe this is something I haven't seen in my own faucets

    There is a screen and a green (at least on mine) plastic piece with an oring which make it a water saving. Faucet
    SuperTech
  • Leon82
    Leon82 Member Posts: 684
    edited February 2019
    Have to pull it out . As you can see there was some sediment in there.
    SuperTech
  • SuperTech
    SuperTech Member Posts: 1,854
    I can definitely see the potential for restriction there! I definitely don't have water saving faucets.
  • Intplm.
    Intplm. Member Posts: 1,417
    @Imshaikh . How far away is the kitchen faucet? Is the kitchen faucet the farthest faucet from the water heater?