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RUR199e conversion

I would like to put the RUR199e outside unit, in my 8' high, vented crawl space.
My thinking is that in the winter the unit may freeze. By bringing the unit inside the crawl space I'll gain 20 degrees or higher ambient temperature and the bonus of re-piping the PEX inside, not exposed when it was an outside application, keeps it from freezing the recirculation line.
The trick is to make an exhaust system that directs 98% of the combustion gases out and away from re-entering that space. Including, placing the vent cap away from reentering the home by windows or air inlet areas.
My thinking is by mounting the unit away from the exterior wall by 5', give or take. I will build a sheet metal connection to the units existing exhaust vent onto the cover of the unit so that the double-walled galvanized 4" piping and using a standard side wall vent cap will remove all the exhaust gases when the unit fires up.
Advice, please.


  • mattmia2
    mattmia2 Member Posts: 9,747
    Unless rinnai sells a conversion kit leave it outside or get a listed indoor model. I think it has freeze protection that can be enabled that runs the burner and recirculation if the temp drops below 40 or so.
  • Slimpickins
    Slimpickins Member Posts: 340
    They make indoor and outdoor units for a reason. The following is from the installation manual. If the information in these instructions is not followed exactly, a fire or explosion may result
    causing property damage, personal injury, or death. Besides the danger, you will void the warranty.