Installing external expansion tank on a tankless water heater

Discussion in 'General Plumbing Help' started by kyoboof, Jan 11, 2019.

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  1. Jan 11, 2019 #1

    kyoboof

    kyoboof

    kyoboof

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    Good evening. I posted previously about my coaire tankless water heater issues and these forums were a great help. I had a pressure reducing valve start leaking/losing pressure.

    With the help of these great forums we replaced the PRV and added an inline pressure gauge to help monitor the pressure.

    2 months later (now) the new PSI gauge sprung a big leak. I replaced the gauge again and all is well.

    This got me thinking. Why did a PSI gauge completely fail 2 months in? Could my expansion tank be bad? the psi guage never reads above 19 psi. Other than the gauge leaking the unit functions properly.

    I shut off the water going to the unit and drained the unit by manually lifting the pressure release valve until the unit had zero pressure at the gauges, I took my pressure gauge and measured the PSI at the expansion tank shrader valve and it measured ZERO. Does this mean my internal expansion tank failed? Did I test it properly?

    If the answer is yes, and the tank has failed. I would like to know if its possible and how to plumb in a external expansion tank. ( if it is possible it will be done by a journeymen gasfitter/plumber) dont worry! Please note this tankless unit also heats my house.

    Attached are some detailed pictures of the unit. The expansion tank is circled in red and I also attached a picture of the gauge that was leaking. hopefully this is enough info.

    Thanks so much.
     

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  2. Jan 14, 2019 #2

    frodo

    frodo

    frodo

    Just call me Macgyver Professional Supporting Member

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