Rinnai R50lsi low hot water pressure.....

Discussion in 'Tankless Water Heater Forum' started by NickB, Apr 9, 2010.

  1. NickB

    NickB New Member

    Apr 9, 2010
    Hi just installed another Rinnai tank-less hot water heater. I am having an issue with this unit. The hot water pressure coming directly out of the unit is very low. The cold water pressure coming into the unit is more than adequate. I checked then inlet screen filter, looked clean. The unit also shut off twice with an #12 error code. The gas pressure is good, incoming cold water pressure good, venting right through the wall so that's not an issue.

    I will be calling Rinnai tomorrow but wanted to see if anyone else has had the same issue.

    Thanks in advance for your replies.
  2. zl700

    zl700 DIY Senior Member

    Aug 26, 2009
    Western NY
    Describe "good gas pressure"
    What is the static pressure when off, full fire, and full fire with other appliances on, measured in inches of water column??

    You bought their smallest unit, look at the performance charts to determine gpm at a given temp rise, it may be all the heater can do.
    Last edited: Apr 10, 2010
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  4. Scott D. Plumber

    Scott D. Plumber In the Trades

    Jun 30, 2009
    Agree, If you are getting #12 codes my guess is that good gas pressure ain't so good. You need between 6-10"ng or 8-13.5LP with a 1" pressure drop or less when running (Dynamic pressure).

    In PA I'd expect the R50 to do a one bath home with a standard shower but not much more. You are looking at about 3-4gpm (ish) from this unit.
  5. gator37

    gator37 Retired prof. engr.

    Nov 10, 2009
    Retired prof. engr.
    You might want to review the manuf. lit., if I remember right those units have a large water pressure drop associated with them.
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