We have a 1" main line coming into the city Water meter. It then goes down to 3/4 in to the hot water and then remains 3/4 to the rest of the house.

In the master shower, we are looking to install the following and I wanted to know if we should use 3/4 or 1/2 for Thermostatic valves and On/off volume control valves.

1. On one side of the shower: 3 jets, shower, hand-held shower. Using one thermostatic valve and 3 on/off Vol controls, we want the ability to turn the jets and shower on, or Jets and handheld on.

Question: Should we use a 3/4 or 1/2? I saw the Grohe 35 026 GrohFlex Universal Rough-In Box which is a 1/2 inlet. Is that sufficient for flow and pressure to run the 3 jets and shower at the same time?


2. Also in the shower, we plan on having a 8" or 10" overhead rain shower with its own thermostatic and no/off valve so someone can control their own temperature and pressure. Question: Should we use a 3/4 or 1/2" rough-in valve?

with each fixture pushing 2.5GPM, what do you recommend?

thanks
Nish

Will you be using Pex? If so then definitely use 3/4".

I'd test the 3/4" main first, to see how many gpm I could get out of it. There are booster pumps that will increase speed based on load.

use 3/4 inch to feed the hot and cold to a 3/4 inch valve.
use a 3/4 volume control for the body sprays and make a loop to feed them.
[ths.gardenweb.com]
1/2 volume control for the handheld
3/4 volume control for the shower head if it is going to be a large size rainhead.

Unless it is a very unusual layout, "body spray loops" are more "busy work" than an actual benefit.

@North Carolina Plumber (NC) - Thanks for your response. Not sure if we are using Pex. I'll need to confirm with the plumber. If we go with copper piping, then should it still be 3/4?

@Paul 48 - What is the best way to test the GPM from the main? What is the minimum required GPM where I can go with an 1/2 valve vs. 3/4?


@Packy (MA) -
So are you suggesting to use a 3/4 thermostatic valve for the shower and jets. Not sure what you mean by 'loop to feed them'.
Why does the volume control for the handheld have to be 1/2 inch. On one side of the shower, we will have a handheld and regular shower (2 showers) and 3 jets. Should they all be 3/4 valves and vol control?

And the seprate rain shower can be 3/4. When you say 'Large size rainshower', what is considered large?

@jk (AZ) - What is a body spray loop?



Edited 1 times.

you can make everything 3/4 if you wish.
1/2 inch to the handheld will be cheaper and plenty big enough..
1/2 to the shower head same thing.. i can't really tell you when i would increase the shower head piping to 3/4 but some of the rain heads are like a car wash..
as for loop body sprays.. have a look at these images...
[www.google.com]
lastly, make sure the drain you choose will handle the higher volume.
lastly, lastly.. water heater must be sized properly as well.

1. So is it possible to have 3/4 as the main and downsize it right before it goes into the thermostatic valve to 1/2?

2. Or I have the possibility to come out of the hot water tank at 1" and then branch (split) to 3/4. One branch would go to the rain shower thermostatic valve. The second 3/4 branch would go to the regular shower and jets Thermostatic valve. both in the master shower.

Once they get to the valve, I can downsize to the 1/2 valve. Is that ok to get good pressure for the 3 jets and shower on one side?