Custom Shower addition plumbing questions

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by alxv, Oct 8, 2008.

  1. alxv

    alxv New Member

    Oct 8, 2008
    Hi to all,
    My first post on here.. hope i'll get some help on some of my questions..

    I'm starting to remodel my bathroom and want to make sure i plan everything ahead. bare with me i'll have many questions and hope you guys can help me..

    Previously the bathroom had only a jet bath and i'm now adding a custom tiled shower.

    Plumbing runs on 1/2 copper lines.

    Tub moves a bit so the drain has to be moved too

    #1 If the drain that was already in places is realy close to were it was before but that the P-trap is not right after the tub drain but maybe a foot further... does this makes a big difference or it as to be right underneat it ?

    The shower i am installing will the the following :

    1 rain shower kohler watertile (see here)

    3 or 4 Kohler watertile bodysprays (see here)

    1 regular Showerhead

    I will use 3 volume control valves for those items and will be all tied up to a thermostatic valve

    #2 I'm worried that a 1/2 pipe won't be enough for this type of system and that the pressure won't be enough... i know for the bodysparays i'm supposed to do a pressure balancing loop. any suggestions??? comments ?

    i'm pretty close to the water heater if that makes a difference.

    #3 since i have no previous experience in this... could all these devices should be run on 1 water line or on multiples ?

    #4 what about the shower drain.. all plumbing surounding this area is 1 1/2.. is having a 2" drain that neccessary ?

    #5 i thought of running PEX instead of copper... would this be a good idea ? or should i just stay with copper ?

    #6 the thermostatic valvel that i looked at are kohler too.. they come or in 1/2" or 3/4". could i use a 3/4 valve with fittings on the water feed? would that help the output ?

    If you want you can look at the specs of the kohler devices i mentionned maybe that will help you in knowing what is needed

    I really thank you all for you help

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    I think you'll have problems with the 1/2" line with what you want to do.

    Kohler has dissappointed me (and it appears others here), and I won't buy anything from them again. Their parts book could be confused as a phone book sitting there since they have the design of the day - parts are unlikely to be stocked, since they don't use the same thing - everybody thinks they can design it better, and they keep changing things.

    A 1/2" valve can probably flow about 6 gallons per minute. Compare that to the specs of the heads you want to run simultaneously. A 3/4" valve could flow more (it's spec'ed to) if it is connected to at least 3/4" supply lines (can you replace back to where it is at least that size?). Picture your hose without a spray head on the end. You get some increased velocity when you restrict the opening...let it just come out of the open pipe with no restriction, and it won't go far. You may have enough heads to emulate that hose with nothing on the end.

    Some of the Kohler stuff is VERY fussy about the rough-in - to about 1/16" or so or the body spray will either stick out too far, or won't tighten down and seal. You have to be really good about setting your tile and determining the position of the fittings.

    For help on tiling, building the shower properly, and to verify the if the floors and structure are okay to support tiling, check out

    Code requires the 2" drain for the shower, so you'll have to run it back until the waste is at least that size. It needs to be vented also...each drain needs its own vent line. they can be combined in the attic or in the wall above the flood plane of the highest thing on that run (probably the sink - must be 6" above the rim - inspectors often look for 42").

    Moving the tub p-trap needs to happen, too. The only issue is maintain the 1/4" per foot slope from the outlet arm of the trap. If this puts it too high, then you've got problems, but probably not terrible.
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  4. alxv

    alxv New Member

    Oct 8, 2008
    Thanks for your reply..
    i gotta say, i'm a bit dissapointed now.. those outlets have a nice look and picked themn because of that.. but did you ever hear at all about those watertiles or you simply have bad experience with other kohler products ? i checked other brand for a nice designed look,, but none of them had what i was looking for..

    If i only have 1/2 line and run 4 shower head that rate at 2,5 gpm i'm already over what the line can provide.. how big of a supply line and valve do you need to provide suffisent pressure to let's say 4 of those bodysprays PLUs the water tile shower rain ceiling device that is said to consume 10 gpm ? do the outlets need to run at cointinous 2,5 gpm to have a good experience ? at that speed, my heating tank will be empty in maximum 5 mins.. or maybe i'm missiing someting and not understanding properly.

    i'll investigate more on what i can do about running a 3/4 line but i doubt it can happen...

    Any experience with Grohe products ?


  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    I've not used the water tiles. The products could be well made, but everything eventually needs maintenance.

    FWIW, I used Grohe products in my remodel. I'm not a pro, but last time I was in London, the shower had a Grohe thermostatically controlled valve, and it worked quite well.

    You can only typically get 70% or so out of a WH before it starts to cool off very noticeably. Multiple shower sprays, heads can be nice, but it is a'll pay for it in water, sewer, and energy costs on a continuing basis, not just in the purchase price - plus, installation requirements are tough, too.

    Check the 3/4" typically will flow about twice that of a 1/2" valve. Course, that is at the same pressure.
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