PEX and Vent Questions

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by monkeystomach, Jul 19, 2010.

  1. monkeystomach

    monkeystomach New Member

    Messages:
    27
    Location:
    VA
    Hi everyone,

    I’m new here, as you can tell by my post count, and I do have some problems I hope you all can help me with.

    First… I tried searching “pex†using the search tool, but every time it says Sorry - no matches. Please try some different terms… I must be searching wrong because I cannot believe that pex has not been talked about somewhere on this site…


    But my main problems are as followed:

    I am trying to install this pedestal sink where a vanity use to be. Since I already ripped all of the drywall down I was going to move the water supply pipes and valves closer together so they would hide behind the pedestal.

    [​IMG]





    Since I’m a regular DIY homeowner, I opted for pex and this is what I have now…

    [​IMG]

    So… I know that my cold water (on the right) cannot stay like that… can it? Is that too much bend in the pex? I do not want to put too much pressure on the fitting. I might have to redo my vent and drain system to get it to work correctly... opinions?

    What about my hot water line? Do I need to attach it to something else, or will the screws in the fitting at the top be enough? Is that angle okay on the hot water line?

    After reading some articles and posts about PEX, I’m a little worried about it now. I might not have all the facts straight but here it goes (please correct me if I’m wrong).
    PEX is great, but the fittings are where the problem is. The fittings use to be a lot thinner which caused them to snap and spray water everywhere. The fittings are now much thicker and breaking is not a problem. However, with thicker fittings there is less water flow…?

    If that is correct, and I have ½ copper, should I use ¾ PEX to get the same flow? Will I notice a difference?


    Sorry for the long crazy post.

    Thanks,
    Monkey
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,152
    Location:
    New England
    The supplies for the sink are fine...pex that diameter can probably be bent into a 6" radius, and you've got nowhere near that angle. Ensure you screw it to the blocking. To minimize the stress right at the fitting, there's no reason why you can't tilt the dog-eared fitting to the incoming pipe, if you wish.

    For the sink, the 1/2" pex will be fine since the flow restrictors required in any vanity faucet will restrict the flow to about 2.2 gpm. But, you may notice a difference if using a multi-head shower system or filling the tub. There, you may want to convert to 3/4, then back to 1/2" at the valve. While a showerhead is restricted to about the same as the vanity, with 1/2" pex supplies to the tub, you will decrease the flow rate, probably noticably unless you go to 3/4" (no big need for a 3/4" valve, use an adapter to get it back down to 1/2"). that being said, mine is plumbed with 1/2" pex, but they used Wirsbo/Uphonor, which uses the expander tool and their fittings. This system does not use crimp rings, the tool is inserted into the end of the pipe, expanded, then you quickly insert the fitting and the pipe collapses around the fitting. Because of the expansion, the flow restriction isn't anywhere near as great since the fitting OD and ID can be larger.
  3. Terry

    Terry Administrator Staff Member

    Messages:
    15,130
    Location:
    Bothell, Washington
    You will need to screw the fittings down to the wood if you expect to thread in brass nipples for the shutoffs.

    The bend on the PEX is fine. We bend it all the time.

    1/2" to a lav faucet is plenty. You have a aerator on the faucet that restricts to 1.5 or 2.0 gallons anyway.

    If PEX was such a problem, we wouldn't be installing it, and the builders wouldn't be asking for it.

    Since you have the wall board out, now is a good time to put the wood backing in for the lav.
  4. nhmaster3015

    nhmaster3015 Master Plumber

    Messages:
    836
    Location:
    The granite state
    In my experience most builders are only interested in cost and getting in and out as fast as possible.
  5. monkeystomach

    monkeystomach New Member

    Messages:
    27
    Location:
    VA
    thanks for the help guys.
  6. monkeystomach

    monkeystomach New Member

    Messages:
    27
    Location:
    VA
    More Pics...

    Hi guys.
    Before I put the last few screws and clamps on the pipe system and put up the drywall I just wanted to check again on the cold water pipe (on the right) to make sure that it is okay and not going to snap and flood my house :)

    [​IMG]
    [​IMG]
    [​IMG]
  7. monkeystomach

    monkeystomach New Member

    Messages:
    27
    Location:
    VA
    some more...

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
  8. monkeystomach

    monkeystomach New Member

    Messages:
    27
    Location:
    VA
    [​IMG]
    [​IMG]

    sorry for the cell phone pics, but they are better than nothing i guess...
    Thanks again!
  9. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    Nope! Your fine with the PEX!

    I'd be more concerned about the ABS with all the cement the plumber slathered on it...
    Sometimes excessive cement can cause joint failure.

    As Terry stated make sure you put in a backer board for the lav sink to screw into so it doesn't rip off the wall when someone leans on it....
  10. Terry

    Terry Administrator Staff Member

    Messages:
    15,130
    Location:
    Bothell, Washington
    Redwood, how can you say that when there are only a few pictures of the PEX to look at.
    There were a few angles I would have liked to have seen.

    Maybe one angle from the Lunar Lander, or from that tall tree in my parents yard.
    You can't be too careful.
  11. shacko

    shacko Master Plumber-Gas Fitter

    Messages:
    561
    Location:
    Rosedale, Md
    I hope you roughed that in to the sinks dimensions that should of come with it, otherwise you will be a unhappy camper when it comes time to hook it up, luck.
  12. Redwood

    Redwood Master Plumber

    Messages:
    7,450
    Location:
    Connecticut
    Yea maybe 5-10 more from angles not covered yet...
Similar Threads: Vent Questions
Forum Title Date
Plumbing Forum, Professional & DIY Advice New bathroom venting questions - w diagram Jul 11, 2014
Plumbing Forum, Professional & DIY Advice Venting Questions for the Pros Apr 30, 2014
Plumbing Forum, Professional & DIY Advice Gas Dryer Vent Questions Feb 16, 2014
Plumbing Forum, Professional & DIY Advice Kitchen Sink Drain/Vent Questions Feb 10, 2014
Plumbing Forum, Professional & DIY Advice Venting Questions Mar 18, 2013

Share This Page