Single handle shower/tub valve recommendations for good flow rate?

Discussion in 'Shower & Bathtub Forum & Blog' started by dunstergirl, Jan 30, 2016.

  1. dunstergirl

    dunstergirl New Member

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    Oct 30, 2007
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    Getting ready to renovate the bathroom and want to find a good quality single-handle mixing/diverter valve that will give us good flow rates at the tub AND shower spouts (before shower head). I was very unhappy with the flow rates from the Moen I put in my last bathroom a couple of years ago.

    We are completely redoing the plumbing so have the option of using either 3/4" or 1/2" pex to the installation from the main lines. I'm willing to spend the money on a more expensive valve if it gives the results we want. We're in Canada in case that makes a difference for codes, although we aren't terribly worried about that.

    I would rather not go with more handles but would consider it if it makes a difference for flow.

    Thank you for any advice.
    Lelani
     
  2. Gary Swart

    Gary Swart In the Trades

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    I use a Delta. I think the number is 1700, but can't swear to that. It has just a single handle with controls on/off and flow. Temperature is controlled by a knob in the center of the fixture. Of course it has the anti scald feature. My plumbing is all copper, but I see no real problem using PEX to connect the water supply to the fixture. Perhaps a copper pipe from the fixture to the shower head would be better than PEX, but maybe there are ways to secure the shower head when using PEX. I've had this fixture for several years, and there well might be newer models out since. Can't comment on other brands.
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    The wall thickness of pex is substantially larger than copper, so 1/2" pex's ID is much closer to 3/8" copper. 1/2" pex's ID= 0.485", 3/4 pex=0.681" while the corresponding copper is: 0.569" for type M 1/2" and 3/4"=0.811". That's a huge difference when you consider the area of the opening has the r-squared factor in it. To get the equivalent of 3/4" copper, you'd need 1" pex (which would have slightly more capacity).

    But, it really depends on what you want and need. Some valve designs have more capacity than others. But, it all depends on what you expect to be using, what you need. At least in the USA, many fixtures are flow restricted, so it normally isn't a big deal.
     
  5. hj

    hj Moderator & Master Plumber Staff Member

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    whatever valve you use will be limited by the openings in the cartridge and shower head, REGARDLESS of the size pipe you use. You will get a bit more capacity by using a Delta valve and inverting it so the shower is fed by the "tub' opening.
     
  6. Smooky

    Smooky In the Trades

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    Last edited: Jan 30, 2016
  7. QueBall

    QueBall New Member

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    Delta gave me a spreadsheet showing the flow rates of their various rough in valves and cartridge combinations at different water pressures.

    Long story short, for a shower only application the greatest flow combination is the R10000-UNBXHF rough in valve with the 17T cartridge giving you 8.61gpm at 60psi water pressure.

    So that is the rough in valve that has no built in shut off stops and no tub outlet along with the high end thermostatic tempassure cartridge.

    If you want both tub and shower, then the R10000-UNBX model gives you 7.32gpm on the shower port and 7.75gpm on the tub port with 17T cartridge at 60psi.

    So if going with Delta and you want maximum flow rates make sure you get the rough in valves without integrated service stops and use the 17T series cartridges. I love the 17T cartridges myself, they are designed to keep consistent water temperature and the fact they give the best flow is just a nice bonus.
    Delta flow rates.png
    Delta part numbers:
    WS = Service stops
    HF = High flow shower model with no tub port on the bottom
     
    csstile and mikek753 like this.
  8. gregmech26

    gregmech26 Member

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    Last edited: Jan 19, 2017
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Realizing, of course that if you did have enough showerheads to use that, with a significant 100g WH, you'd probably get still less than 10-minutes of a shower, depending on how hot you made it (in the cold of winter, you'd get less since you'd need more hot water outlet to offset the super cold, cold water inlet)! It would make it nice filling a big tub, though!
     
  10. rjbphd

    rjbphd In the Trades

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    You probably had the basement garbage, Moen Postitemp. . However, the Moen.. Moentrol is a way better made and much more volume than most of the run of the mill faucets out there.
     
  11. gregmech26

    gregmech26 Member

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    Even with just one "old school" shower head with the water-savers removed (that offers 10 gpm), all I would really need in addition to a 100 gallon WH is enough psi from the city to maximize my "old school" shower head. Or am I wrong?
     
  12. csstile

    csstile New Member

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  13. csstile

    csstile New Member

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    I'm curious as to where you got the GPM flow chart? Great reference! I've looked on Delta's site, Build.com, etc. but GPM specs are no where to be found. The all-in-one spec sheet for all Delta R10000 rough-in valves has no GPM specs.

    As an FYI the 17T cartridge (RP47201) is listing for $353.95! Ridiculous! And Build.com is offering NO discount from that price! A 17S (RP46463)is only $117.15!

    17T https://www.deltafaucet.com/parts-product-detail?modelNumber=RP47201

    17S https://www.build.com/search?term=rp46463

    Can I assume that the "17S" cartridge is the default cartridge for all Delta 17-Series shower trim packages?

    We purchased a 17 Series Linden shower system with H20 shower head and 4 body sprays that totals 8GPM. I hope there water pressure is high which I'll check tomorrow. I'm sure they are not going to want to spend another $353.95 x 2 for there two shower head shower! Next time if a customer wants a Delta fixture with a body spray option I'll recommend a Delta 17T series or try to convince them to go with Kohler with 3/4" rough-in valves.

    Finally, I sent a few questions to Delta and one question was "Why doesn't Delta offer a competitive 3/4" rough-in valve? to match Kohler. The response should be interesting!
     
  14. csstile

    csstile New Member

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    Your thinking old school water tank. Get a tankless and you won't run out of hot water! :)
     
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Most thermostatically controlled valves tend to have a higher maximum flow than a single-handle type. I think it's because they run full hot and control the amount of cold required to keep it at the desired temperature rather than adjusting the balance between the hot and cold, and in most cases, will never run the full volume of either except at cold.

    Try to get 18gpm with a tankless, and you'll probably need 3-4 of them...not exactly an inexpensive setup. Especially, when you consider the size of the gas line you'd need to run them.
     
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