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Tankless Instant Hot Water for Gravity Retrofit

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Tim Daley
Tim Daley Member Posts: 1
in THE MAIN WALL
Can an old (vintage 1920's) cast iron gas hot water heater in a gravity system be replaced with a tankless instant hot water heater (such as an Aquastar) and a circulator?

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  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    It could, but...

    the pump required to overcome the pressure drop of the heater is substantial. Like 185 watts per hour. You would also need an additional pump for the loop. You'd also have to provide some means of long term condensation production control. And you would not be able to utilize it for DHW production without a tank/exchanger combination.

    Like I said, you could, but...

    ME
  • jp_2
    jp_2 Member Posts: 1,935
    aquastar

    I was told that none of the aquastars will have a warranty in a heating application. they are no longer making the one they suggested for radiant heat? so, sounds like they are having problems. I tried to use one, temp would always runaway. not that efficient, approx 76%.
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