3/4" or 1/2" question

[Gregavi]

Greetings,
I am a General Contractor and I have used many professional plumbers over the years. For a bathroom for instance, I have had some plumbers run 3/4" copper all the way to the the shower valve or faucet or tub valve and then adapt down to the necessary 1/2" for connection. I have had other plumbers adapt down to 1/2" right after the last "branch off" and run the 1/2" the rest of the way. In either case, they always tell me their way is best. Opinions??? What is the better way and why? Leave it 3/4" as long as possible or adapt down after the last "branch off"?

Thanks in advance.

 

[Matt30]

Greetings,
I am a General Contractor and I have used many professional plumbers over the years. For a bathroom for instance, I have had some plumbers run 3/4" copper all the way to the the shower valve or faucet or tub valve and then adapt down to the necessary 1/2" for connection. I have had other plumbers adapt down to 1/2" right after the last "branch off" and run the 1/2" the rest of the way. In either case, they always tell me their way is best. Opinions??? What is the better way and why? Leave it 3/4" as long as possible or adapt down after the last "branch off"?

Thanks in advance.

I've done it both ways. I have noticed no difference in either if your whole system is sized right. Most faucets are pressure balanced anyway

 

[frodo]

I've done it both ways. I have noticed no difference in eitherif the whole system is sized right . Most faucets are pressure balanced anyway

i agree completely

depends on a lot of factors. pressure, volume, length, number of fixtures.




Copper Tubes


Nominal Pipe Size

(in)--------
------------------ Water Content (Gallons/ft)
-----------------Type K------------Type L------------ Type M
1/8 ------ 0.0014----- 0.0016----- 0.0016
1/4----- 0.0039----- 0.0040----- 0.0043
3/8----- 0.0066----- 0.0075----- 0.0083
1/2----- 0.0113----- 0.0121----- 0.0132
5/8----- 0.0173 ----- 0.0181 ----- 0.0194
3/4----- 0.0226----- 0.0251----- 0.0268
1 0.----- 0404 ----- 0.0429 ----- 0.0454
•1 Gallon (U.S.) = 3.785x10-3 m3 = 3.785 dm3 (liter) = 231 in3 = 0.13368 ft3 = 4.951x10-3 yd3 = 0.8327 Imp. gal (UK) = 4 Quarts = 8 Pints

 

[Mr_David]

cost is biggest factor I think. That is if you're running copper.
Another thing to consider is if you run 3/4' on the hot side, it will take longer for the shower to get hot, because you have to displace more cold water that was dormant in line. now if you're not living in Southern Calif in a severe drought climate and you have plenty of water, mores always better. install 2 , 3, maybe even 4 heads. better run 1" and add another valve.

 

[frodo]

rule of thumb in plumbing

1/2'' to 1 fixture

3/4 to 2 fixtures then use a 3/4x1/2x1/2 tee


if you run all 1/2'' hot line..you will notice a drop in volume while taking a shower when another fixture is turned on

 

[Gregavi]

Thanks to all. Very informative. I do live in SoCal but we're going to run 3/4" all the way anyway and use a recirc pump to solve the water waste issue.