Supply size for shower heads body sprays 10 gpm ?

heathead

Have 75 psi water. Supply to house is 1 inch then down to 3/4. Current bath has 1/2 copper run about 20 feet to tub with three 90 elbows. I am installing 4 2.5 gallon spray heads. 10 gpm on 1/2 split between hot and cold makes me think the hot is not enough in the winter when it will be 90 percent flow though the hot water pipe. I am thinking about running another 1/2 hot and tying in making it then become 3/4. Could one justify doing just the hot and not the cold. Access is limited with the original copper pipe run. Other wise I would just change it all out. Thanks for the thoughts if I need to run cold also and make sure the extra line is needed. Thanks

hot_rod

replace both with 3/4 if you can. You only talking 20 feet. This table gives you an idea of flow rates. Ideally you want to be around 4 fps, but for an intermittent load PHCC tables allow up to 8fps.

There may be times when you are flowing 100% hot as the water heater drains down.
Got enough water heater to keep up with that demand?

heathead

Hot Rod, thank you for the input. I can't change them to 3/4 would have to rip out kitchen. I found a way to pick up the 1/2 from the sink faucets that are in the bath room, and join them to the shower. Two 1/2 pipes from different feeds in the house. Any problems except longer to wait for hot water. I wonder if they will act as gravity hot water Re-circulation some what. I love your heated shower ideas in previous posts and incorporating them into this bath remodel. I used one zone for the floor and shower walls all together, what do you normally do. Can you send some pictures of you shower wall radiant piping. Thanks again.

Paul48

"Got enough water heater to keep up with that demand"?

Maybe that went un-noticed. It's very important. Clock the flow, because you can do anything you want , but if you can't get it from the street, you're done.

hot_rod

heathead said:

Hot Rod, thank you for the input. I can't change them to 3/4 would have to rip out kitchen. I found a way to pick up the 1/2 from the sink faucets that are in the bath room, and join them to the shower. Two 1/2 pipes from different feeds in the house. Any problems except longer to wait for hot water. I wonder if they will act as gravity hot water Re-circulation some what. I love your heated shower ideas in previous posts and incorporating them into this bath remodel. I used one zone for the floor and shower walls all together, what do you normally do. Can you send some pictures of you shower wall radiant piping. Thanks again.

Sounds like a manifold approach? Sure multiple lines would increase available flow, as long as the other end of those sink runs connects to a 3/4 line?

Any way to snake 3/4 pex across the kitchen, add that to the 1/2 at the shower?

Hilly

@Hotrod where did you find that nice little tool?

Larry Weingarten

Hello: How about smallifying the problem and using 1.5 gpm showerheads? Niagra makes some good ones. Reducing flow by 40% couldn't hurt, plumbing-wise.

Yours, Larry

hot_rod

Hilly said:

@Hotrod where did you find that nice little tool?

The little calc wheel? It came as part of our membership in the PHCC many years ago. It must be 25 plus years old.

I'd guess there are electronic versions in this day and age, like the System Syzer wheel?

Abracadabra

Larry Weingarten said:

Hello: How about smallifying the problem and using 1.5 gpm showerheads? Niagra makes some good ones. Reducing flow by 40% couldn't hurt, plumbing-wise.

Yours, Larry

Larry, in my experience, people that are interested in having a mega car-wash style shower with his/hers shower heads, rain heads, body sprays, etc. are not going to be worried about 1.5gpm spray heads, nor would they want them.