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.

Rinnai Code 25

I've inherited an 11-year-old tankless system with the new house I just bought. If we run hot water for more than about 10 minutes, we get "Code 25." The condensate line runs into the same wall as the hot-pressure-release valve output, presumably connecting to the same pipe outside.


  • Slimpickens
    Slimpickens Member Posts: 1
    Your condensate is backing up and grounding out on the screws on top the trap where the green and white wires go. Pex is not a suitable drain material especially with the barb fittings. You should have an air gap on the discharge drain and the relief and condensate lines should be separate. For an air gap, use a 1/2 FIP PVC adapter on tank connection with a close nipple glued in, then use a 1/2 PVC tee and use the run of the tee to continue down to drain. On the branch of the tee, use a short nipple and a elbow pointed up with a 3' nipple. This will help the condensate drain better and if the condensate drain ever did clog, it won't back up into the heater.