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Rinnai condensation build up -plugging outlet

okotoks Member Posts: 2
edited December 2017 in Domestic Hot Water
I have a Rinnai that is 9 yrs old and has been a PITA since we built the house and it was installed. Several issues have been rectified however the one that is lingering is that I am clogging up my condensation hose with an almost cement-like substance. I have changed the hose out twice and have drained it directly down into a bucket. I have been receiving error codes of 12, 11 and 10. The intake/exhaust is clear. Water flow is good. Flushed out/serviced 12 months ago.
It finally quit and I pulled the hose off the collar the outlet was plugged with a grey/black concrete like substance. I cleaned out as best as I could and pulled out large chunks of material. Works fine again.
Anyone know what this could be and how to fix/mitigate.


  • Jack
    Jack Member Posts: 1,047
    What model is it? What “several” mistakes have been rectified and how long did the unit operate with those mistakes. How is the unit vented, terminated (are the clearances met) and how is the drain line run?
  • okotoks
    okotoks Member Posts: 2

    Thanks for the help. Sorry I haven't been updating more.

    The issue is the venting that was used when it was installed. The condensation is returning to the unit and it is corroding the aluminum exhaust material and running into the unit. The resulting aluminum sludge is cooking and clogging up the condensation collar and not allowing the water to escape into the drain hose. The liquid is draining into the unit and causing an error code of 12.
    I'm not happy that this material was used in the first place. This has had to be identified in the past.
    I broke down and replaced it with an IBC Boiler with a new design system for my DHW and slab heating. Hopefully this will sort out the issues.