Rinnai RUR199I Recirculation Pump Noise

Discussion in 'Tankless Water Heater Forum' started by db3058, Apr 7, 2021.

  1. db3058

    db3058 New Member

    Joined:
    May 10, 2013
    Location:
    San Jose, CA
    I installed a Rinnai tankless with a dedicated re circulation line on one side of a 4000 ft home (There is a standard tank water heater on the other side). The tank water heater removed for the tankless had a passive re circulation line that was used for the return line. It worked with the tank and works now. I have 2 one way valves and an expansion tank set to 60 PSI to prevent hammer between the one way valves. The tankless works fine. The water has a long way travel, probably 150 ft from the Rinnai, under the house to the 2nd story master bedroom. It serves 1 whirlpool bath, 1 regular bath with shower, one shower with 2 outlet heads and 5 faucets. Water is set to 125. Main line is 3/4", recirc line is 1/2". There's only 2 of us in the house.

    Although I'm getting old and harder of hearing I can clearly hear the re-circulation pump operating in 3 rooms of the house, where the recirc line obviously travels through. It's loudest closest to the tankless. The copper lines are insulated everywhere I have access to them under the house, where most of the travel is.

    Is there any way to muffle the sound of the recirculating water? It's a low sound but easily heard and annoying.
     
  2. breplum

    breplum Member

    Joined:
    Oct 2, 2004
    Occupation:
    Plumbing and heating contractor
    Location:
    San Francisco Bay Area
    Does the Rinnai model you have support that 150ft for half inch copper?
    I am not aware that any of their units would be designed for that constriction, and within that range you also have to take elbow equivalent length as add on footage.
    Likely also that the hot piping did not include long sweep elbows, so that, and maybe some sloppy reaming of the copper tube will all be contributing to velocity noise.
    Your best bet at this point is to utilize either the timer option or wifi control to minimize recirc run time.
    It wouldn't hurt to up-size the accessible pipe run under the house and eliminate elbows as much as possible with 3/4"pex.
     
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  4. db3058

    db3058 New Member

    Joined:
    May 10, 2013
    Location:
    San Jose, CA
     
  5. db3058

    db3058 New Member

    Joined:
    May 10, 2013
    Location:
    San Jose, CA
    It's just the recirc line that's 1/2". I bought this house and so I couldn't design how the pipe was run or properly ream the insides of the pipe. Thank you for your response. I'll look into the timer option.
     
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