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tankless water heater

JackFre Member Posts: 225
Tankless water heaters are all about flow and temp rise. If you feed a Rinnai R53i, 50F water and you want 120F hot water you will get 4.5gallons/min all day long at the 120F. If you feed it 40F water it will make 3.9gpm at 120F all day long. Typically ground water is going to be (at least here in MA), 52F, according to the US Geological survey. However, if your water line is buried close to the ground and the frost can drive down to it you can hit the 40F cold water supply temp. This will usually happen in Jan, Feb and March time period. So, the unit will work fine you will just see reduced output when you are feeding it very cold water.

Check out foreverhotwater.com. for more info


  • Sonya_2
    Sonya_2 Member Posts: 2
    Tankless water heaters

    I was looking to replace my old 50 gallon water heater with a new tankless on-demand type. Problem is that I've just been told that "the tankless type doesn't work here because our water supply system runs about 45 degrees. And tankless water heaters need a water supply of 55 degrees or more. Is this correct?
  • Elmer Fudd_2
    Elmer Fudd_2 Member Posts: 3
    Tankless instantenous hot water heaters

    I have been looking it to these because I have a small mechanical space and the $300 tax credit.

    More of the major concern I have been reading about is at low flow conditions. some of the heaters need a minimum flow of .75 gpm. if you fall below the minimum flow the unit shuts off. you get cold water, turn the water hotter the heater goes on and you get water that is to hot. some require .5 gpm but I am still concerned at this flow. i am thinkg about installing a small storage tank with a dedicated circ pump. more expensive but again my main goal is to make more space in my utility room. I have a hard time believing all of the hype about the energy savings.

    also the size of the gas line. I only have a 1/2" line to my propane tank which I am not sure if it big enough to run the tankless water heaters.

    Hard water is a concern. even with a softener my water is hard. with the small piping in the heat exchanger I am not sure how it will last

    things to consider - I am still planning on doing it if the cost is not to much.

  • Kniggit
    Kniggit Member Posts: 123

    Look into electrics the Seisco is assembled in Texas and has been fairly reliable, our only issue with them has been temperature sensors, but I have never replaced the same sensor twice, they say they had a bad batch, and the parts were free. we had two leaky tanks but again, free parts not a big issue, they have always handled our problems quickly.

    The biggest issue with the electric tankless is the fact that they use about 120 amps when they are one, however this is usualy only for short periods of time.

    We have installed a couple gas tankless, and never been on any call backs that were the fault of the unit, only the owner's lack of understanding.
    Good luck
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