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Indirect Water Heater Swap

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Greetings everyone, I currently have a WeilMclain GV4 Series3 88000 BTU output NG boiler that has a Bock indirect WH model CT30 connected. The coil piping is 3/4" and that is what this Bock is supposed to be. The Bock is 20 years old, on city water. I have acquired a new HTP Superstor condender SSC35 that I will soon install. My problem is that the SSC coil piping is one inch. I'd like to know if I reduce the coil out to 3/4" how much recovery time will suffer? The circulater currently used is a Grundfos UP 15-42fr.



There is more going on with the boiler itself but I don't want to mire things with a deluge of questions yet :) Thanks for your help with this issue..

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  • Zman
    Zman Member Posts: 7,572
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    Indirect

    Assumptions:

    20 piping,8-90's 1-check valve.



    With the 3/4" you are at 5.9 GPM

    with 1" it is 8.2 GPM.



    If your boiler is 84% efficient it will output about 74,000 BTU/hr

    With the 1" you will have a delta T of 74,000/500/8.2= 18 degrees

    With the 3/4" 74,000/500/5.9= 25 degrees



    There are a handful of other factors like whether the indirect can absorb all those BTU's and whether the boiler will run in condensation mode once thermal equilibrium is reached. The manual is the "For Dummies" version so it would take a call to manufacture to figure that one out.



    Long story short...

    If it was a new install it should be 1".

    As a replacement, there will be little or no performance sacrifice with the 3/4"



    OK,

    NOW will you let Dan go?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Docfletcher
    Docfletcher Member Posts: 487
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    Dan's Release

    Thank you. Just a moment please while I unshackle Dan... The deed is done he's all yours.







    .
  • Docfletcher
    Docfletcher Member Posts: 487
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    My new HTP SSC35 has been in service for a just over a week now. I piped it 1" copper up to the ball valves where I reduced to 3/4". I am very pleased with the performance. Recovery is very fast, less than 15 minutes.

    The boiler condensate used to drip constantly out the hose onto the garage floor. Quite noticeable. However, since the new water heater has been in it has not dripped at all. Do you know why this would be so?
  • Zman
    Zman Member Posts: 7,572
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    I would say that either the condensate drain is plugged or the boiler is returning hotter water and boiler is not condensing as much.
    With most boilers you can adjust the supply water temp in DHW mode.
    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Docfletcher
    Docfletcher Member Posts: 487
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    I don't have a provision to adjust the temp of water temp going through the coil. I'm sure coil water is at boiler water temp 180/185F. The return feels less worm but not by much... For what that's worth :) There is no mechanical device to moderate the temp. I took condensate line off & there is water did flow from it.
    Thanks, Don
    l
  • Zman
    Zman Member Posts: 7,572
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    I originally thought that was a condensing boiler. It is not.
    The fact that it is not condensing is a good thing.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Docfletcher
    Docfletcher Member Posts: 487
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    That's good to know. I think everything is back on a even keel with this boiler.
    In the first post above there is a error where I said it was a series 3. It is not. It is a series 2. Thanks again.
  • Docfletcher
    Docfletcher Member Posts: 487
    edited November 2014
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    End