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Twinning HWH's Parallel or Series ??

ScottMP Member Posts: 5,884
You would'nt happen to be a rep would you ? :)

Thanks for the advice


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  • ScottMP
    ScottMP Member Posts: 5,884
    I need to add to an exsting

    50 gallon gas HWH. Its not enough for the customer and its only a year old. The house was renovated and another company put it in.

    I'd rather not pull out a year old tank and they have Forced hot air. I guess adding a second tank is the best way but with tanks of different volume I was worry about drawing evenly. I see no reason to put in another 50 and was going for a 40 but maube that will draw better in parallel ?

    Just having a brain cramp.

    Or would I be O.K. coming out of the 50 and letting the 40 kick on as the temp in its tank drops ?


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  • Hi Scott

    Parallel for high flow rate, series for capacity, in general, in my opinion.

    You might consider a basic storage tank, recirc into it as well as feed the cold into it, and let the heater heat both tanks after the water passes through the storage tank.

    Choices, choices....

  • jp_2
    jp_2 Member Posts: 1,935

    two crappy HWH will cost over 4,000,000 Btu's in wasted energy-losses per year.

    properly sized an on-demand is the way to go.

    why use 1930's technology here?
  • Big Ed
    Big Ed Member Posts: 1,117

    You would install them in series if your looking for hotter water like in comerical aplacations.

    Parallel for volume in residental .Make sure both tanks are sitting the same hight . I like to connect though the lower drain ports. Use a reverse return pipe set up for even resistance.
  • ScottMP
    ScottMP Member Posts: 5,884
    Theres more than one way

    to skin a cat pal. I can't figure what would be best for them. So I put in a good storage tank and that outlasts the HWH ???

    What to do ??

    Would a fourty and a fifty draw evenly ??


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  • jp_2
    jp_2 Member Posts: 1,935

    just been playing with some numbers lately.

    I had bad experience with them, but that could have been my fault, more and more they make sense.

    work some numbers out and tell me!

    if you have 1/2F loss per hour per tank, times 24hr times 365 days, see what you get!

    this site generally boosts about the europeans beening way ahead of us but then poop poop on-demands that are all over europe????? you'll see more on this topic later.

    ps putting tanks in series will more than double your output.
  • Weezbo
    Weezbo Member Posts: 6,232

    i would think it depends on what the fixture load and the time load happened to be.

    i think that if you had an on demand instant hot water at the tap(recirc system)lashed up, and then depending on if that was on a timer would also have some bearing on the best plan. i tend to like the idea of a simple storage tank and have the anti scald valve dually installed as per code on the water heater.
    Weezbo *~/:)
  • ScottMP
    ScottMP Member Posts: 5,884
    I agree JP

    and I have some issuies with Tankless. There not for every application. I think a small european house with one bath and located right next to the ktichen and bathroom , they work well. Put this in a house with three baths and mutli head shower and three kids .... I don't know if there right. Living in N.E. we have a low temperature input duing the winter.


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  • jp_2
    jp_2 Member Posts: 1,935
    on-demand in series w/tank?

    how about if you put an on-demand in series(down stream) with a tank heater?

    in low usage, hot water would past through the on-demand but not trigger it to fire(already hot), as the tank falls behind the on-demand tops off the temperature to 110F or something like that?

    keeps your standby losses low.
  • jp_2
    jp_2 Member Posts: 1,935
    big Ed,

    putting tanks in series can't increase water temp, will actually decrease temp! will be around the average of the two tanks.

    unless you are thinking of the second tank as a booster, then in a way you can say they increase temp.
  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
    Add storage tank

    Seeing as the water heater is new, why not just hook up a 2nd storage tank with a bronze recirc pump. Minimal losses through the 2nd tank(no flue). It should certainly outlast the original water heater - it doesn't see thermal shock of a flame.

    Think of this - two water heater's means two replacement installations in 10 years or so. If he used a storage tank, that might last 15 - 20 years or more.

    Adding an instantaneous heater may not be so easy. You still has to vent it somehow. Also have to consider gas supply. Is there an extra 250,000 btu's of capacity in the gas line?

    my $.02
  • ScottMP
    ScottMP Member Posts: 5,884
    Thanks for all the input

    Some days you just get a brain cramp and get stuck. " Honey, How do you spell Y-O-U ? "

    I'm going with the storage tank.

    This is what makes the wall great. I have all the wallies to ask question to.


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  • Jamie Pompetti_2
    Jamie Pompetti_2 Member Posts: 62

    Personally, we have never had any issues with tankless HWH. I think they are a great thing. They save space and money. Not to mention the the increase in efficiency and they last twice as long as a standard HWH.

    I've had one in my own home for 5 years and have no complaints. We have a two story four bedroom house with three kids (two are girls) my bride and I.

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  • tim smith
    tim smith Member Posts: 2,398
    Additional hot water

    I would think a tankless in series with water heater would be a great way to go if you have recirc. 1st in line would be tankless then into tank for buffer then out to system. Time the recirc for high useage times. Turn down the gas water heater so it would only come on if tankless failed. Then when tank does fail, if needed put in good storage tank or just another simple water heater. Would be pretty slick I think. Tim
  • jackchips_2
    jackchips_2 Member Posts: 1,338
    I realize

    you have already made a decision, Scott but wanted to add my two cents.

    When my wife wanted the pool heated I added a Takagi direct fired and put it before the 50 gallon gas water heater, in series.

    Not only do I heat our pool during the summer but we have not run out of hot water since. Even with the 50 gallon heater my wife would run it cold and I'd wait half an hour to shower. Not any more.

    Many solutions, much good advice and your choice is one of them.

  • Big Ed
    Big Ed Member Posts: 1,117
    My Mistake

    I read the post quickly from my cell phone.Old age and working long days are not helping me either...

    I Thought they were direct fired heaters .Thanks JP..

    Back to work.....Where are my glasses.................
  • Rich Kontny_3
    Rich Kontny_3 Member Posts: 562
    Tankless Worksheet

    Rheem/Ruud who uses Poloma for their on demand models has an excellant worksheet to see if the on demand is right for particular installations. Just go to their website and look it up.

    If you are sticking with two standard heaters then reverse return is the best way to go with the heaters piping arrangement as it provides forthe even flow and cycling of both heaters.

    Rich K.
  • jp_2
    jp_2 Member Posts: 1,935
    we all

    big ed, I think we all are guilty of reading posts too fast from time to time!!!! I know I am.
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