Recirculation pump questions -- Please help

Discussion in 'Tankless Water Heater Forum' started by rafael, Nov 2, 2010.

  1. rafael

    rafael New Member

    Messages:
    18
    Location:
    SF
    I've got a Noritz N-069M for my two bathroom home. It mostly works, but there are a few problems. Specifically, it takes about 30 seconds for hot water to come out of the farthest fixture. And as far as I can tell, the dishwasher and clothes waster don't get much, if any, hot water unless I turn on the hot water about 30 seconds before starting a load.

    Do you think a Metlund pump or some other type of recirculation pump would help? Why or why not? These things are pretty expensive. I'm willing to pay the cost, but only if it will allow me to quit wasting so much water. Any thoughts?

    Also, if I do install one, it most likely will go in the master bath room, which is just a few feet from where we sleep. How loud are these things?

    Thanks for any help or wisdom you can provide.

    Rafael
  2. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    30 seconds at 2 GPM with 1/2" pipe is about 100' of pipe. If the pipe is shorter some of the 30 seconds is water heater response time.

    If you get a recirc pump it has to be larger than 0.5 GPM.

    With all the ifs, ands & buts in this manual
    http://www.noritz.com/u/installation_manual__n_069m_n_063s.pdf
    I'm surprised you get any hot water.

    You might want to check your fuel input rate on your gas meter when the heater is on, pg. 26.
    Last edited: Nov 3, 2010
  3. rafael

    rafael New Member

    Messages:
    18
    Location:
    SF
    Thanks for the response, Thatguy. I'm a novice in these matters, so I'm having a little trouble figuring out what the upshot of your comments are. If I understand you correctly, you seem to be saying that 30 seconds is a long time for hot water to start coming out of the fixtures. Is that correct? Someone told me it takes my model about 6 seconds to deliver hot water. Does that sound right to you?

    You seem to have a pretty low opinion of this model. Why?

    Finally, what is the reason for checking my fuel input rate on my gas meter, and how exactly do I go about doing that?

    Thanks again.
  4. Thatguy

    Thatguy Homeowner

    Messages:
    1,459
    Location:
    MD
    With a 6 second response time and 2 GPM water flow and 30 seconds total wait, the pipe to the heater should be no longer than 80'. Otherwise there is a problem to be pursued.

    I believe very few people are happy with tankless heaters but I can't confirm this. I guess sales per capita in the US of tankless vs. "other" heaters might give a clue.

    When the heater is running, time how many cubic feet of gas is used per minute. This quantity can be converted into BTU per hour and compared with the input rating of your heater.
    Last edited: Nov 4, 2010
  5. rafael

    rafael New Member

    Messages:
    18
    Location:
    SF
    My home is so small that there literally is no place to put a tank water heater.

    I'd like to try the test you describe with the gas meter. Do you know where I'd find step-by-step instructions to do that?
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,015
    Location:
    New England
    The readout on your gas meter is likely fairly standard. If you can't figure it out, ask your gas company, or check their website on how to read your meter...it's pretty simple.
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