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Thread: 1.25" Main Vs 1" Line

  1. #1
    Network Engineer rmelo99's Avatar
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    Default 1.25" Main Vs 1" Line

    I have a 1.25" main line that comes into the house. It currently is soft(not so much) but not straight copper after the main shutoff. I want to replace this wavy 28' of piping from the main valve up.

    Main valve is a new ball valve so I'm not worried bout that, my concern more about is there a big difference between 1" and 1.25". I want to keep it at 1.25" but that size tubing is not as common and readily available and there is premium on it b.c of that. What am I losing if anything going down to 1"?

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    In the Trades Gary Swart's Avatar
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    There is a significant difference between 1" and 1-1/4" pipe, figure the area of each with the formula, Pi (3.14) x radius squared and you can see. That said, 1" is plenty large enough for a normal household. Many homes has just 3/4". Now, if you are talking about a quarter of mile of pipe, then you would have to take friction loss into account, but that's only for an extremely long run.

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    Forum Admin, Expert Plumber Terry's Avatar
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    Here is a nice chart for sizing

    http://www.terrylove.com/watersize.htm

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    Network Engineer rmelo99's Avatar
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    Ok, thanks for the chart, looks like there are several reasons for me to not bush it down to 1".

    Need to check now if the meter is 3.4" or 1".

    I'm sure I can make do with 1" supplying the house but, I may in the near future install a sprinkler system, and I think I will need as much volume/pressure as I can. Correct?

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    1" should be more than enough for any standard house, even with an irrigation system.

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    In the Trades Gary Swart's Avatar
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    I have a 1" line out of a 1" meter for my house and irrigation system and there is plenty of flow.

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    Moderator & Master Plumber hj's Avatar
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    Default Copper

    If you were to use 1 1/4" soft copper as a replacement, unless you were a very good and very careful installer, you would wind up with a pipe that supplied less water than a 1" copper line, because you would kink it at least once, and maybe several times while unrolling it, and it would be oval rather than round once you had it installed. We use copper up to 1" and PVC for anything larger than that.

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    Network Engineer rmelo99's Avatar
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    I didn't even think about pvc.

    I agree that I wouldn't consider using soft copper. That is what is there now and it is all wavy, complete with flared ends!

    Now by PVC u mean CPVC right? Isn't that what the kind for supplies is called?
    I have to imagine that is waaay cheaper than copper, right?

    What's the consensus on 1.25" CPVC for my main line "inside" the house? Keep in mind the whole house has been replumed in PEX. I need this main run to go back and feed my manifolds.

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    Moderator & Master Plumber hj's Avatar
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    Default pipe

    If this is inside the house, I assume then that it is overhead, I WOULD use copper, but not soft copper or plastic. Either 1 1/4" type "M" which is less exensive or 1", but rigid 20' lengths of either. If it is inside the house then we need more information as to the situation.

  10. #10
    Network Engineer rmelo99's Avatar
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    I think I would be using 10' sections of copper. Any reason to use "L"?

    I priced 1" fittings the other day at HD and they were in the $6-8 each? Does that sound right? I checked online at pexsupply dot com and their fittings are a fraction of that.

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