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We're redoing our bathroom. I'd like to have a tub spout, two body jets, and shower head.

Original Plan

My original plan was to have the hot and cold water lines come into a mixing valve, run a line from mixing valve down to spout and up to diverter valve, and then from diverter into either a pressure stabilization loop for the jets or to the shower head.

The problem is that we run this very same setup in the basement. And when I divert 50% of the water to the body jets the shower head becomes very limited, and I lose a lot of shower head water to a trickle that just falls to the floor. It is an underwhelming experience.

Proposed Alternative

Given that I assume, and a quick Google search seems to tentatively confirm, mixing valves cause some level of flow restriction or are designed to only allow a certain maximum flow rate, I can at least partially blame the valve for not providing enough pressure.

So I'm wondering if it may may sense to put a T in the hot and cold water lines, then run lines to two different mixing valves. One mixing valve would feed the tub spout and shower, while the other feeds the body jets. My hope is that this would accomplish two things:

  1. Increased overall flow rate as each mixing valve can allow its maximum flow to reach its single outlet. (so I get mixing valve max flow rate x2)
  2. More granular control over flow rate to shower jets (right now it's 50/50 if both are on, which may not be desirable)

Will these goals be accomplished? Are there any other reasons not to do this?

Components

I've settled on Delta components at this point. I'm going to connect everything using pex and Sharkbite fittings.

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  • For more flow rate you need bigger pipe diameter from the house inlet. The more pipe openings(faucets) you have open at one time, the less flow/pressure from all.
    – crip659
    Mar 11, 2023 at 21:01
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    You'll use more water faster. So you'll hit cold water faster, whether that be from an "instant" hot water heater that can't keep up, or using up the heated water in a tank water heater. Or you need commercial-scale water heating. Faster than that, you may use up your available pressure, depending on supply line size.
    – Ecnerwal
    Mar 11, 2023 at 21:21
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    I just finished a bathroom. For all the cost of the in-wall valves, nipples etc and the fact they are buried in tile, I wish I had gone with a good column/panel that combines all the things you said, costs less, looks better, is easier to maintain and the required plumbing in wall is just hot and cold feed.
    – jay613
    Mar 11, 2023 at 22:00
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    If you go in-wall, Delta has integrated diverter valves. They are expensive but they are designed for what you want, and guaranteed.
    – jay613
    Mar 11, 2023 at 22:02

1 Answer 1

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It's not that mixing valves have a flow restriction particularly. Everything has a flow restriction.

The problem is simply that you have not adequately sized your water supply equipment for the extra water outlets you have added. Most consumer tier mixing valves, diverters, etc. are sized for typical American showerheads. If you do unusual things, you need unusual equipment.

Unfortunately - and here's the part you're not gonna like - unusual equipment isn't made in million quantity, so it fails to benefit from economies of scale so cost to you is considerably higher.

Your proposal is to simply use two commodity mixing valves in parallel. Sure, if everything else they share is up to the flow. Still, it could have the annoyance of the body jets having a different temperature than the showerhead, and having cognitive dissonance when wanting to deal with a too-cold or too-hot spray in a hurry. As such, it seems to me like a cheap-ass hillbilly solution. I would hold out for better.

As far as mixing body vs showerhead, I would want total control there, allowing either one to go 0% to 100% independent of each other (so increasing body sprayers doesn't decrease showerhead). You know, like two simple valves!

I'm not a fan of high shower flow for another reason: the tanked heater won't last very long, and the tankless will require ridiculous electric power. It's possible to get a tankless heater that runs on Putin Juice, of course, and at 200,000 BTU they can serve the need.

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