# Water Pipe Size for Double Shower



## slakker (May 29, 2007)

Do you want to operate both all the time or just some of the time...

I'm not sure if there is a specific code for this, but I have a 8" rain shower and a hand show head attached to a single mixer with 2 volume controls. I used standard 1/2 OD in PEX to feed hot and cold and have no problems with water pressure.

I also used a temp control mixer too, and the temp for the second shower head is around 1 degree cooler that the first. Apparently it's part of the design from the manufacturer...

A friend installed a "human car wash" with 13 shower heads. 6 front and 6 back in 2 vertical rows of 3 each/row and a 12" rain shower. He fed it with 1/2 copper for hot/cold and he definitely does not have the pressure nor the volume to feed it. So it'll be a combination of volume (which I think is limited by the inner diameter of the pipe) and pressure....


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## froddan (Jun 14, 2007)

Slakker,
Thanks for your post!



slakker said:


> Do you want to operate both all the time or just some of the time...
> I would prefer to have the option to operate one or both at the same time.
> 
> Your setup sounds similar to what I would like to accomplish...
> ...


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## slakker (May 29, 2007)

froddan said:


> Your setup sounds similar to what I would like to accomplish...
> One large shower head (possibly coming from the ceiling) and a hand shower head on the side.
> Is yours one single valve, or are there two valves?
> I have copper pipes in my place - so I will have to stick with that, but the principle seem to be very similar.
> If you are happy with yours, what brand and model is it?


I'm very happy with the setup... I bought the Paini product and I think bang for buck, it's much better value than the more popular brands such as Kohler, Moen, etc.

The temp control mixer has one valve built in to control one of the shower head, and in my case, I used it to control the rain shower. The bottom of the mixer has a plug that can be removed and attached to a second valve to control the other shower head. The difference is that this second outlet is around 1 degrees Celsius lower in temp. In this way, you can control one, the other or both shower heads at once.

BTW, my wife was also the one that persisted in needing this setup and am glad she did. But she's a designer, so I just build what she designs...


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## froddan (Jun 14, 2007)

Ha ha, sounds like we are in the same boat...wife designs, we build...
As long as it works out it is a good deal I think.

I will look into that product to see what they offer.
At this point I am mostly confused about what pipe size is recommended for such as setup. If 1/2" copper pipe is fine I am all set, otherwise I would upgrade to 3/4".

Thanks again!


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## jogr (Jul 24, 2007)

If it was me I'd run a separate 1/2" for each shower head off the 3/4" for both hot and cold. You could either extend the 3/4 or run both 1/2s off where the 3/4 ends now. That way you know you'll have enough pressure.


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## froddan (Jun 14, 2007)

Jogr, thanks for your post!

I think that will make alot of sence. I've been researching valves, and most of them, if not all, seem to be 1/2" so your suggestion makes a lot of sence.
At least common sense, that's all I have...not sure about my Plumbing Sence 

Any ideas of if it matter where to split the 3/4" into the 2 1/2" pipes?
Does running a longer 1/2" reduce pressure?

Thanks again!!!


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## jogr (Jul 24, 2007)

I doubt ther'd be any pressure drop or flow decrease in 1/2" pipe in normal residential distances. You could branch off right where the 3/4 ends (3 feet from the shower). Are your hot and cold lines both 3/4" up to near the shower?


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## froddan (Jun 14, 2007)

Both hot and cold are 3/4" about 3-5 feet away from the shower.

These lines feed another bathroom too though, with a tub-shower, sink, and toilet. I doubt both bathrooms will often be used at the same time.


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## ktkelly (Apr 7, 2007)

I did my master bathroom recently (pics in the my project section) with all Groehe products.

1 Fixed Shower Head
1 Handheld Shower Head (on a slide bar)
3 Body Spray

1 Temp Control/Mixing Valve
3 Shut Off Valves

Since this was a second floor that had 1/2" lines, I went with that, even though the Groehe specs called for 3/4" for the unit I was sold (discounted deal, so I took it)..

With both shower heads and the 3 body sprays on, it still has more than adequate waterflow.:yes: 

_*BUT*......._

If I could have run 3/4", I would have. It *will *make a difference.

*FWIW:*

Rather than a ceiling head, I would use a standard wall head and a sliding, hand held as I did. I really believe you'll get more use out of that arrangement.

It's really nice having the hot water coming from all those different directions. Plus if you want, you can shower together without fighting to see who get the water...:laughing:


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## troubleseeker (Sep 25, 2006)

I would tee from the 3/4" with a separate 1/2" line to each hot and cold inlet. Set the 3/4" tee so that the incoming water feeds into the side outlet, thus hitting a "dead end" and forcing water to go in both directions for a balanced flow when both showers are on at the same time. If you set the tee so that one shower is fed straight through, the shower fed from the side tap will get less water pressure when they are both on, as water will take the path of least resistence, which is to the shower head that is fed in a straight line through the tee. It will not be very noticable with two small, highly restrictive low flow heads, as they will keep suficient pressure in the supply lines because of their low volume. But with large volume heads, the difference will be very obvious.


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## froddan (Jun 14, 2007)

*Ktkelly - Which Model*

Ktkelly,
Thanks for your reply, sounds like you have a great set-up.
Do you happen to have the model number, or a link to the product you used?
Did Groehe ask for a 3/4" valve, or just the line before it split?

Thanks again!



ktkelly said:


> I did my master bathroom recently (pics in the my project section) with all Groehe products.
> 
> 1 Fixed Shower Head
> 1 Handheld Shower Head (on a slide bar)
> ...


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## ktkelly (Apr 7, 2007)

First go to:

http://www.grohecatalog.com

Select categories tab.

Select "Shower/Safety Valves". Mine is the Grohtemp (34-902). The Grohtemp is offered as either a 1/2" or 3/4" valve. You also need one of the trims.

Select categories tab.

Select Shower Valves/Volume Controls/Diverters. Pick out the ones that fit you applications.

Select categories tab.

Select Shower Products for heads, etc.

The style that I have is no longer in production, that's partly why I got a pretty serious discount. Not cheap stuff by any means, but it is definitely very well made. And Grohe support is excellent!

The installation instructions can be a bit of a pain to decode, but one call to tech and you're good to go. Or you can ask me. I might know the answer. Might....:wink: 

Got to laugh at myself. I've been spelling the name wrong the entire post....:laughing:


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