3/4" vs. 1/2"

[crosby1]

i have 1/2" supply to the bathroom.

when installing a mixing valve and controls for a custom shower, do i have to use 1/2" valves or can i use 3/4" valves? should i plumb the 1/2" supply to a 3/4" mixing valve and then use 3/4" pipe for the remainder of the installation?

i guess what i'm asking is this: would the flow be better with 3/4" pipe or am i limited by the 1/2" supply so should i just stick with 1/2" valves?

the other issue is that the kohler valve i'm looking at only comes in 3/4" so should i use 3/4" pipe for the installation or 1/2" and use reducers where needed?

or does it matter at all?

thanks.
pietre.

 

[Jadnashua]

Depends...a valve designed for 3/4" supplies will be able to flow more water than one designed for 1/2" supplies. Course, that doesn't mean you are going to have that much demand. If you are going to have multiple showerheads, you will probably be unsatisfied with a 1/2" supply line that is shared with the rest of the bathroom. Calculate how much flow you want to have in the shower, and get back with the answer.

 

[Sponsor]

 

[Geniescience]

i have 1/2" supply to the bathroom. .....

pietre

You can do it any of the ways you described.

Since your supply is only 1/2" to start with. Whatever makes sense to you.

If you increase the pipe size to 3/4", its beneficial effect is the same as if the 3/4" piece were first and the 1/2" piece were second in line. In other words, the loss of flow is a linear sum of all the losses in the system, and the order doesn't matter. You get a bit less pipe noise, and a bit more flow.

How long is the total distance involved? The total length of pipe. How many elbows are there going to be? How good is flow so far? How much flow do you need? How many shower heads or jets?

David

 

[crosby1]

thanks very much david.

the total length of pipe from the 1/2" hot and cold supplies will be around 8 - 10 feet (rough estimate). i'm planning on a standard shower head and an overhead rainshower (wife's idea). i imagine there will be 2 perhaps 3 elbows on each. i don't have an exact measurement on the flow now, but my kids call the shower the "nipple peeler" if that gives you an idea.

so, are you saying it's better to go with the 3/4" pipe after the initial mixing valve? will that give me more flow to the showerheads than using 1/2"?

there's no way i can re-plumb the hot and cold supplies to the bathroom with 3/4" pipe...that would involve a total house renovation and i'm not quite ready for that yet.

 

[Geniescience]

so, are you saying it's better to go with the 3/4" pipe after the initial mixing valve? will that give me more flow to the showerheads than using 1/2"?

well, i don't want to encourage you to go to ridiculous lengths all for no palpable improvement.

in raw and absolute terms, if you are thinking like a pure scientist, yes there is an improvement in flow if a segment is plumbed using 3/4" pipe.

Now I read in the above post that you are asking me if using 3/4" pipe for the distance from the mixing valve to the shower head would be "worth" doing. Hmm.

That amounts to a distance of about 42" and one elbow, more or less... Not much. But, yes, go ahead and plumb it with 3/4" if you really want to. Nobody can tell you in advance whether you will notice the difference, in my opinion.

I would do it. I like big pipe.

David