Questions about PEX repipe project

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Tally Wacher, Nov 15, 2015.

  1. Tally Wacher

    Tally Wacher New Member

    Joined:
    Nov 15, 2015
    Location:
    Texas
    Hello gentlemen (and Ladies if there are any on here), I'm going to be embarking on a repipe of my 1960s built 2800 sqft one story home's galvanized pipes in the up coming weeks. We have been in it for about 4 months and have had a leak at a copper to Galvy with a dielectric union repair done by the previous owner over the master lavs. The owner before that had a leak repaired over the kitchen, but not sure what was done. I stop-gapped it with some of the that pipe wrap that is similar to the stuff you use to make casts with.

    I figure I would post all my questions and show my progress in one thread.

    I'd appreciate all the help I can get.

    So the meter size is 5/8th and copper to the building at the front left corner. The copper service goes into a bib and then into the house. Please see the attached JPEG, sorry about the rendering.

    So the first question is to manifold or not? The service comes in from the left front corner and the water heater is in the back right of the house. I could Tee off the 3/4" cold trunk after it comes in from front the left corner and run one cold trunk to supply the left side and one to supply the right side with 1/2" drops and water heater with 3/4". I could do the same for the hot water with 3/4" trunk and 1/2" drops or I could home run the hot water. Not sure where I would place the manifold. Maybe 3/4" into the attic and put the manifold there and run the 1/2" to each fixture. The wife and kids complain about it taking so long for hot water. Will blow in lots of insulation after the repipe is done. Thanks and keep checking back.
     

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  2. CountryBumkin

    CountryBumkin Active Member

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    Location:
    Orlando, FL
    I would use a manifold system - that's the beauty of PEX. Do a hot water return loop while your at it.
    There are plenty of websites/suppliers available. This is one I've used a lot. http://www.supplyhouse.com/pex
    I used the "ProPEX" (AquaPEX) system.
     
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  4. Reach4

    Reach4 Well-Known Member

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    [Irrelevant information accidentally posted to this thread moved to the appropriate thread.]
     
    Last edited: Nov 16, 2015
  5. Tally Wacher

    Tally Wacher New Member

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    Location:
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    Thanks for taking the time to comment.

    So should I put the manifold in the attic and run the hot water 3/4" line to it? Don't really look forward to making a big hole in the drywall or top plate for all the hot home run 1/2" lines. Manabloc or copper manifold? Speaking of Viega, does the Manabloc play nice with the Uponor expansion system or do I have to crimp to connect to the manifold?

    I have been looking at the supplyhouse web site for a couple of months and have the Milwaukee tool coming in the mail. Will most likely go with aquapex.
     
  6. Tally Wacher

    Tally Wacher New Member

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    Location:
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    I don't have any PB pipe in my system, so not sure to what you are referring. About Apollo, I've seen some of the fittings at the local Lowes. Can one use the brass or EP Apollo fittings (or Sharkbite EP fittings at Home Depot) with the Uponor expansion system? Thanks.
     
  7. Reach4

    Reach4 Well-Known Member

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    IL
    You cannot use the Uponor expansion system except with PEX A, such as Uponor . My understanding is that you can use other fittings with PEX A, but PEX A costs significantly more than PEX B, such as Apollo that you might get at Lowes..

    My mistake. I accidentally responded to the wrong thread.
     
    Last edited: Nov 16, 2015
  8. CountryBumkin

    CountryBumkin Active Member

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    There are adapters for PB to PEX, if you need one - such as this http://www.supplyhouse.com/Wirsbo-Uponor-LF4585050-ProPEX-LF-Brass-to-PB-Coupling-1-2-PEX-x-1-2-PB
    The location of the manifold depends on how easy it is to access and install. I put mine in the garage next to the water heater where the water comes in (from Well). The Manabloc system is nice, and you can use the AquaPEX pipe and fittings. See this chart http://www.supplyhouse.com/PEX-Tubing-516000
    I used the Uponor AquaPEX and their "copper manifold" which allowed some customization of the layout. http://www.supplyhouse.com/ProPEX-Copper-Manifolds-519000
     
  9. Tally Wacher

    Tally Wacher New Member

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    That is the issue with my particular situation. Water heater is in the utility room in the back right corner of the house and attic access is on the other side of the house. Then I'd blow in about 3 feet of insulation after the repipe, so access to the manifold would be difficult. Really do not want to make a big cavity between the 2x4s of the wall to mount the manifold not to mention all the drilling of the top plate to route the 9 or so hot 1/2" lines. The other option of running the 3/4" hot to the in-attic located manifold is more appealing, but still does not deal with access issues.

    On the subject of a hot-water circulation loop, a home run system would not make it needed, right? If I truck and branch the system, I'd run the hot line back to the water heater and Tee it into the cold water supply going into the water heater?
     
  10. Master Plumber Mark

    Master Plumber Mark Sensitivity trainer and plumber of mens souls

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    Being that you are talking about installing a pex maifold in the attic,
    I assume that you are in a warmer climate??? things generally freeze if
    installed in the attic in a lot of areas north of texas and arizona...and florida.

    Even if you are in Texas or arizona
    both the hot and cold lines at that manifold will be like very warm bath water for a minute
    or two before it would chill out.... and you also have to figure they will sweat like a pig up there...

    just wondering if any of this pertains to you......

    manifolds have their place but are really not as cost effective and energy
    efficient as simple straight pipeing.....
     
  11. CountryBumkin

    CountryBumkin Active Member

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    I think you could install your manifold in the attic, but you need to consider the temperature up there. I have some PEX running through the attic and I was told to (and did) run insulated PEX. I'm in FL so my attic gets around 100+ in the summer and that could cause my cold water pipes to get real hot. I think if you did a manifold up there you would want to build an insulated cabinet for the manifold and/or insulate the pipes as much as possible.

    On the hot water recirculation system, a Home Run layout would not contribute to recirculation on its own. You would need a gravity loop or a recirculation pump to get the hot water to return to the cold water side (usually back at the Hot Water Tank).
    See http://www.finehomebuilding.com/des...mart-details/hot-water-circulation-loops.aspx or Google it for more ideas.

    And http://www.finehomebuilding.com/item/4829/three-designs-for-pex-plumbing-systems
     
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Depending on where you put a manifold, it would be fairly easy to run a recirculation line from it back to the WH, and depending on how long the runs were, may still help a lot. That would only work if the manifold could be central to the more critical points of use so that those lengths from the manifold would be minimized. Otherwise, you'd need a lot more runs. Trying to get a gravity recirculation system to work with pex is harder than with copper since any slight dip could be enough to stop convection...it's easier to run rigid pipe with the required slope and expect it to stay there.

    Depending on how the ceiling joists run in the attic, it may be tough to keep the pipes insulated. Ideally, it would run next to the ceiling, below the insulation there so it would stay near ceiling temperature. Keep in mind that insulation only slows heat transfer...it does not make any heat and if there's none there in the first place, things can freeze. The pex pipe itself usually isn't damaged, but fittings and manifolds are not so lucky! Super heated attics and the water in the pipe, even if the pipe run was made with insulated pex, will get to ambient there...it could be enough to scald you on the cold water, depending on where you live.
     
  13. Tally Wacher

    Tally Wacher New Member

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    Location:
    Texas
    I'm in Houston and in the summer my cold water is very hot. I would home run the hot water lines and trunk and branch the cold water lines due where the water comes into the house and location of the water heater. I have thought about insulating the cold water lines to help with condensation. I would blow in insulation on top of all the pex after everything was done anyway so I'm not sure insulating the hot and cold lines would be anymore beneficial than having insulation blown on top.

    The way my galvy plumbing is laid out now it takes a long time to get hot water, like 4 minutes as timds by my teen daughter. I was thinking of sticking with the cold water layout and either home run or Teeing the hot with one side to feed the right side and the other to feed the left side of the house.


    Appreciate you input and thoughtful insight.
     
    Last edited by a moderator: Mar 1, 2020
  14. Tally Wacher

    Tally Wacher New Member

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    Did you insulate both hot and cold lines? Did you use pex with pre-installed insulation?

    I have an old under the lav recirc pump I got from costco. I could probably use that on the return line to pump the hot water back to the cold side at the water heater or under the furthest lav. This is assuming that I use a trunk and branch because if I home run I don't see how recirc would benefit because it would recirc only to that lav. I could run a return from line from the furthest hot fixture to the pump at the water heater but that is a trunk and branch set up. I guess you could loop a home run system but that would mean return lines for all hot fixtures.
     
  15. Tally Wacher

    Tally Wacher New Member

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    I don't have much choice because of the layout, but the manifold would have to be close to the water heater. I could run two lavs of one 1/2" line to the baths and that washer and half bath. Running a recirc from the manifold would work if I used sub manifolds. I would run a 3/4" from water heater to the attic and Tee it off to a 3 valve sub manifold to feed the kitchen sink, lav in the half bath, and washer. The other part of the Tee would be run to the other side of the house to feed the bathrooms with everything getting its own 1/2" line except the lavs sharing 1/2" lines. Then I'd run a 3/4" or 1/2" line back to the recirc pump at the water heater and tie it into the cold water feed line.
     
    Last edited by a moderator: Mar 1, 2020
  16. CountryBumkin

    CountryBumkin Active Member

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    I bought the pre-insulated PEX lines.

    I only did the recirculation line for the master bedroom (which is furthest from the WH and needed it the most). I ran a new hot water feed and hot water return through the attic.

    For now, I left the original cold water line as is (coming up from under the slab for the bathroom's cold water supply). Someday I will replace that line with PEX too.

    I don't plan to do a hot water recirculation loop for the other full-bathroom (or 1/2 bath) since it close to WH (and doesn't get used much).
     
  17. Reach4

    Reach4 Well-Known Member

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    If you don't add a mixer to mix cold into your hot, that will be simpler and efficient. People will want you to have such a device. If you feel compelled to do that, consider not having it at the water heater.
     
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    New England
    Where I live, code requires a tempering valve for ALL hot water sources (except WM and DW), and it's prudent in all situations. You can run one 1/2" pex line to the shower, and another to feed the toilet and sink, but you will have issues if you use one for all of the fixtures unless you are the only person ever in that bathroom. Trying to feed more than one room with a single 1/2" pipe is asking for issues. You may or may not notice an issue with the hot line when using the shower, but would if you were trying to fill a tub and someone was using the sink at the same time. 4-minutes to get hot means you're probably throwing away 10-20 gallons of water down the drain to the sewer, and that also means that you've refilled the WH with that much cold water than then needs to be reheated, making what's left cooler and effectively making the tank look smaller. Makes a recirculation system seem cheap. ANd the convenience factor is nice, too.

    WIth some valves, you could probably get by with one recirculation line looping past all of the fixtures
     
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