Two Shower Heads on One 1/2" Supply???

[ande8414]

Hi All!

I am new here but keep seeing this thread when I google questions so thank you so much in advance for any experience you're willing to share!

I want to run two shower heads next to each other on the same wall. It will be rare they both run together

but still nice to have available. Currently we have a typical 1/2" copper supply. My thought is to just tee off the existing 1/2" supply lines and run up to two separate pressure balancing valves and then heads. My wife has her eye on two heads with 2.5 gpm flow each (5 gpm total). Would that still have decent pressure enough to enjoy? I feel like low flow heads around 1.8 gpm each would help maintain some better backpressure but wonder what you all think?

Separately, has anyone tried those latest low flow heads with the little filtration balls stating "200% more pressure!" Now that I'm searching for shower heads, those are the only ads on my social media.

Please and thanks so much for your thoughts!
__________________
Robbie

 

[Breplum]

More info please.
Best to know what your existing house pressure is.
And how long the run and the size of the trunk.
do you have 3/4" cold supply at the water heater.

 

[Sponsor]

 

[ande8414]

More info please.
Best to know what your existing house pressure is.
And how long the run and the size of the trunk.
do you have 3/4" cold supply at the water heater.

Thank you! It is 3/4" supply initially. I would guess I could rip up the floor and find the 3/4" main where it reduces down to 1/2", just haven't decided how motivated I should be to find it. This is the master bath upstairs, roughly 1.5 floors. I'd estimate around 30-45 feet or so of length. I should get a gauge and see what I have for pressure there. Thank you!!

 

[Jadnashua]

Shower heads are rated for NGT 2.5gpm each. A typical 1/2" shower valve is rated for 5-7gpm depending on its design. The Copper Institute calls for hot water velocity in pipes to not exceed 5fps, and on 1/2" pipes, that equates to 4gpm, less than what 2 shower heads can flow. Depending on how cold the cold is, in the winter, you'd be likely to exceed the maximum recommended flow rate. A 3/4" line can flow double that to 8gpm at the same velocity.

Shower heads' nozzles cause a restriction...that causes the water to accelerate through them. The pressure stays the same, and many people confuse velocity with pressure. AN open hose has the same actual pressure as one with a nozzle on it, but one with a nozzle will have the exiting water flowing faster. You won't get that acceleration unless you can flow enough volume to them.

So, depends on the valve you choose, and the specific flow rate of the shower heads involved.

Keep in mind that a typical tub/shower valve has two outlets. The one normally used for the shower has a built-in restrictor. If you want more than one shower head, you should probably use the full-port outlet designed for the tub, which is usually on the bottom. You might be able to drill out the restriction on the (normally) top outlet, but be careful, you could damage the valve, depending on its design. Safer to use the one designed for the tub.

 

[ande8414]

Thank you so much, Jim! I'm definitely going to see what current capacity is, and really like the great explanation. You got me thinking now about maximum flow capacity for the freestanding tub we're going to do next to the shower. Similarly, previous supply to the old tub was again 1/2" supplies. Would be amazing to find the 3/4" main and get more like 6-8+ gpm to the tub instead of 4 or so.

 

[ande8414]

Hi All!

Minor updates - timed some flow rates and then bought some parts! Guest bathroom flowed about 1.7 GPM from the shower head and 4.1 from the tub spout. Slower than I hoped but oh well. We got this two head controller. Super excited about it. https://decorativeplumbingonline.com...hoCetQQAvD_BwE

Also got two low flow shower heads to go with it! Figure we'll run only one probably 90% of the time. Hopefully will be fine.

I also have another new uncertainty I'd be grateful for your thoughts on. I want to put the tub plumbing in a ledge wall, which is an addition to a cold wall. Essentially a 2x6 ledge wall infront of the 2x6 cold wall. Is it okay to run plumbing right next to a cold wall as long as it's in the warm space? And then what order of materials would be correct from the cold wall? Should I just drywall once after the second wall? Only one vapor barrier? I'm not sure whether to leave the vapor barrier, then drywall and redgaurd, or I have a bunch of goboard, and then tile it. Please and thanks!!

 

[Sylvan]

I ran three heads off a Delta shower body.

One was high and when I used the diverter then the two on the side walls would work.

I did use a 1/2 copper supply, low flow showerheads

The reason the CDA gave a warning about the velocity on the hot water is it can cause erosion BUT that would depend on the temperature normally found in hydronic systems which can exceed 180 DEG

A shower should never exceed 120 DEG F so the point is mute

 

[ande8414]

Thank you both so much! That makes me feel much better about our decision.

On that insulated wall in the picture, how would you guys finish it with another 2x6 ledge wall framed in front? Currently shown, with the pink insulation and partial vapor barrier, should I finish that wall with drywall first to segregate the ledge wall? Or silly to drywall twice? I have a bunch of goboard so I was thinking maybe seam tape and finish the vapor barrier to the floor, then frame in the 2x6 ledge wall, add tub plumbing, goboard, and then tile it. Would that make sense? Thank you!

 

[ande8414]

Hi All,

Thanks so much for all of your help lately. Here is my latest curiosity and silly question. For the shower, I'm leaning regular drywall and Kerdi membrane (no vapor barrier). Then for remaining painted and tiled walls around the freestanding tub, I'm leaning vapor barrier plus regular drywall. What if I don't bring the shower width even with a stud, and thus stop the kerdi membrane before I get to my vapor barrier with plain drywall? What would be best in that uncertain transition point? Or is it a better idea to transition right at a stud? Bad sketch attached with this idea in mind. Please and thanks for your thoughts!

 

[Jadnashua]

You don't want a moisture sandwich between two vapor barriers. What you could do where the Kerdi will cover the area up to the stud is to take a razor knife and put some strategic slices in the plastic that would prevent sandwiching any moisture that might get through. Kerdi is waterproof, and suitable for a residential steam shower (to work in a commercial application, you have to use the thicker Kerdi), but is not totally vapor proof.

I've found www.johnbridge.com to be my go-to spot for help with tiling things that aren't directly plumbing related.

 

[ande8414]

Thank you so much!

That does seem like a good idea. Thanks and I'll try to keep it strictly plumbing here. I did ask the same question there also but you're the quickest so thanks so much!