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.

HELP! Trying to descale a Rinnai r85

I came across this message board while searching for help.

I just bought a house with an r85 tankless water heater and during the home inspection, the inspector said I should be sure to descale it once a year. As the house was a flip after a foreclosure, I'm pretty certain this hasn't been done in a long time and the high amount of dust confirmed my theory. I followed all of the instructions that I saw online, bought the pump, hose, bucket, vinegar, etc. and then when I went to hook everything up I can't find where the hoses would go! Going off of an old manual I found online, the hook-ups should be underneath what I can see but as you can tell in the photos, underneath the hot waterheater is just the side of my house.

The hook-ups are labeled (L to R) water outlet, water inlet and gas.

Am I missing something completely here that is obvious to everyone? Please be kind if I am! This is my first home. Is this a job where I should get a plumber involved? I can't seem to find anywhere else that all of these things hook up to.


  • lchmb
    lchmb Member Posts: 2,997
    that's actually kinda scary.... the prv should be piped 3/4. The isolation valves needed to hook and pump were not installed. The gas line looks under sized for the unit... you could shut off the cold supply and disconnect the hot line.. run a couple hoses and pump through the system with the unit off..
  • nickmvalente
    nickmvalente Member Posts: 2
    Thanks for the reply. From what you are saying, I should probably call a professional to come and make these fixes? I'm a little handy but im not comfortable cutting pipes.

    Judging by what I've seen in the house, there used to be a regular hot water heater and this was added on at some other time.