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  1. #1
    Join Date
    Mar 2008
    Posts
    11

    Default Upgrading to PEX

    I have a small house that has a rat's nest of copper piping that's been patched and extended and capped over the years. I'm doing a kitchen remodel and heating system upgrade (switching from air to hydronic), and have decided to just rip it all out and switch to PEX.

    I am planning not to do a manifold because the house is tiny, but rather a 3/4" trunk with 1/2" branches to the fixtures.

    However, every pipe in the house is 1/2" at the moment, including the pipe that connects the main shutoff to the inlet of the water meter. I'm pretty comfortable changing out the pipe at the outlet of the meter, but should I change this inlet pipe to 3/4" copper to match? Seems like a real bottleneck.

    Or maybe I don't NEED 3/4" and should just stick with 1/2" everywhere?

    Thanks,
    Eric

  2. #2
    Join Date
    Aug 2007
    Posts
    443

    Default Re: Upgrading to PEX

    I'm sure you'll get advocates on both sides of the ledger on this issue.

    The trunk lines from the water meter, as you note should be 3/4"---then 1/2" to the fixtures.

    I prefer copper because of its neat appearance & low cost of its fittings.

    On the other hand, if you live in a northern climate, PEX is much less likely to burst if the house loses heat in freezing weather.

    Since the cost of copper has shot up in recent months, nearly everyone is using PEX for such things as new distribution lines for a HW heating system.
    Last edited by JacktheShack; 03-14-2008 at 01:02 PM.

  3. #3
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Upgrading to PEX

    Usually the water feed to the meter is one of two sizes .... the older 5/8 inch or the more common 3/4 inch.
    It's not uncommon to see the transition downsized to 1/2 inch copper with the 5/8 couplings attached to inlet of the meter and 1/2 copper feed for the home from the outlet of the meter. Sometimes this is done to maintain a required pressure level but this can have an impact by reducing the gpm flow.

    If the incoming water pressure can be maintained at a reasonable pressure of around 50 psi with 3/4 inch feed that would be an ideal situation.

    I agree with JacktheShack ...... having the 3/4 inch tubing for the main feed trunk and the 1/2 inch tubing for the branches would be nice for providing good flow distribution .... proving the supply can support this.

    The other thing is in a smaller home .... if the distance of the run is reasonably short then the 1/2 inch trunk and branch may be reasonable with little impact of flow distribution.


    Just a thought.

  4. #4
    Join Date
    Mar 2008
    Posts
    11

    Default Re: Upgrading to PEX

    Thanks for the insight. I think I'll leave it alone for now, and see what kind of pressure I measure at the outlet.

    Eric

  5. #5
    Join Date
    Oct 2007
    Posts
    32

    Default Re: Upgrading to PEX

    Define tiny, as in the size of the house. I did a PEX home run style system in my 1380 sq ft house. Built my own manifolds out of brass 3/4x3/4x1/2" tees and ran a 1/2" hot & 1/2" cold line to each of 4 rooms about 25' each, using about 225' total. Including fittings, & tool rental, the whole thing cost around $250. Originally there were 1" galvanized trunks running to the farthest room & it was taking 2 min to get hot. Now its 20 sec for any room. It was really worth it!
    When I pulled permits for the addition this was part of, I was advised to go at least 1" pipe from the meter, that way the water line was upgraded for all future use. Did 1 1/2" & have no pressure probs. City delivery is pretty high pressure in my area, esp. being almost across the street from the well. If you can swing it, I would really consider a home run system. Don't buy a 20-fitting manifold, just make your own to suit your needs. Just don't forget to add shutoff valves everywhere you might want them, like to individual runs & a master before thy "manifold."

  6. #6
    Join Date
    Oct 2007
    Posts
    32

    Default Re: Upgrading to PEX

    About the 1 1/2" supply, the way the guy at the permit counter explained it, larger diamerter pipe is going to reduce wear on the inside of the pipe. Compare 1 gpm moving through 1/2" pipe. 1 gallon of water has to move quickly through the pipe. Now if the pipe was 1", it would move 4X SLOWER because 1" has twice the area of 3/4", which has twice the area of 1/2" pipe. Slower water movement is supposed to equal less wear on the insides of the pipe, but I am sure there are some experts here who can verify or refute that, as needs be.

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