How can I increase volume for large rain shower head

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Jeff-ATX

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I'm remodeling my shower and have a 12in rain shower head I want to use. I installed a smaller version 6in in the other shower and the volume isn't too bad. It doesn't spray with much force but a decent amount of water does come out. I'm concerned the larger 12in isn't going to work. I have a standard Moen thermostatic valve with 1/2in pex coming in. The builders also stubbed out additional hot and cold lines and capped them.

My question is how can I increase the volume of water for this large rain shower head? Do I need to add the additional pex lines or can I increase the size from 1/2in to 3/4in from the valve to the shower head?

Thanks!
 
Your issue is the 1/2" pex line coming into the valve. This will need to be changed if you'd like more volume.
 
Jeff-ATX said:
I'm remodeling my shower and have a 12in rain shower head I want to use. I installed a smaller version 6in in the other shower and the volume isn't too bad. It doesn't spray with much force but a decent amount of water does come out. I'm concerned the larger 12in isn't going to work. I have a standard Moen thermostatic valve with 1/2in pex coming in. The builders also stubbed out additional hot and cold lines and capped them.

My question is how can I increase the volume of water for this large rain shower head? Do I need to add the additional pex lines or can I increase the size from 1/2in to 3/4in from the valve to the shower head?

Thanks!
Click to expand...

what size is feeding the shower

the 2 pipes hot/cold coming to the mixng valve ?
they need to be 3/4 minmum


also what is the mixing valve outlet gpm rating ?
what is the shower head gpm rating ?
 
1/2in pex supply lines connected to 1/2in copper connected to the valve. The box for the shower head says max 2.5 GPM.

I have a manabloc system and my biggest concern is adding additional supply lines or upgrading to 3/4in for this shower. I'd rather not have to rip into the drywall in order to feed the pex to it.
 
Are you sure it is a the THERMOSTATIC valve and not a Positemp which is a pressure balanced valve.

I looked up the Moen thermostatic valves which are not very common.
probably due to their $1,000 plus price range.

The thermo valves all seem to be 3/4"

2.5 gpm max to shower head
http://www.moen.com/shared/docs/product-specifications/ts3116sp.pdf

Positemp valve is only 1.8 gpm max flow to shower head
http://www.moen.com/shared/docs/product-specifications/82603sp.pdf

3/4" line to a 1/2" ported valve probably wont make much difference.
 
Last edited:
if you want more volume you have no choice. run 3/4''

and 3/4''' pex in my opinion is to small for your application

3/8'' pex id is .360 .... pex 1/2'' ID is .485 ...... and 3/4 pex ID is .681


3/8'' id .402.... 1/2'' copper is .587...... and 3/4 copper id is .745

do you see that your 1/2'' pex is about the same size as 3/8'' copper tubing ?
 
I have a moen 10 in rain head fed by 1/2pex and the volume is terrific
 
Mr_David said:
Are you sure it is a the THERMOSTATIC valve and not a Positemp which is a pressure balanced valve.

I looked up the Moen thermostatic valves which are not very common.
probably due to their $1,000 plus price range.

The thermo valves all seem to be 3/4"

2.5 gpm max to shower head
http://www.moen.com/shared/docs/product-specifications/ts3116sp.pdf

Positemp valve is only 1.8 gpm max flow to shower head
http://www.moen.com/shared/docs/product-specifications/82603sp.pdf

3/4" line to a 1/2" ported valve probably wont make much difference.
Click to expand...

Yes, it is a Positemp. Sorry. I got them mixed up.
 
There seems to be conflicting opinions so it's difficult to know who's right.
 
You aren't trying to put it on a regular shower arm out the wall are you? If so, You probably won't get it like that. They perform better when ran from overhead, as that is what the are designed for.
 
No, I'm not attaching the shower head to an arm in the wall. It'll be coming straight down from the ceiling.

I'm putting up the last few pieces of cement board that closes off the valve and I want to make sure I don't need additional supply lines, larger supply lines, or a valve that can handle a greater volume of water.
 
Last edited:
you have been cautioned, 1/2'' pex does not have the volume you are seeking.

you need a minimum 3/4'' pex line from man block to shower

.you are trying to install a kickass shower using the smallest piping size you can.
does not work that way. good luck, let us know how it turns out
 
Just curious does your home have a pressure reducing valve? If so put your pressure gauge on and check static pressure with nothing flowing. Then leave a faucet on and check pressure, if it drops more than 5 or 10 psi you may have found a problem.
 
I think I mis-quoted the flow rate on this shower head. It says the max is 2.5 GPM but then it says "For use with valves rated at 1.87 GPM or less. Thanks to Mr_David for pointing out that my valve is rated at 1.8 GPM so I think I'm ok as is.
 
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