Supply line diameter

[cscjjd]

Hi,
My question is about pipe diameters and how it affects available water in the home. I will be replacing the last 35 feet of an existing 1200 foot supply line. The supply line is 1” diameter but it connects to 3/4" pipe going into the home (through the foundation).

If I use 35 feet of 1” pipe followed by a 1” x ¾” coupling, will I get better available water into the home than if I just use 35 feet of ¾” pipe?

 

[ShaunCorbs]

Yes best not to reduce

 

[king of pipes]

I would agree keep it large as possible. Kop

 

[cscjjd]

Thanks for the replies. I just thought that since the line is reduced to 3/4" before entering the house (at the foundation) perhaps it wouldn't make too much of a difference to reduce it 35' sooner. (Using 3/4" for the replacement section would have several advantages for me if it does not substantially affect the water usage in the house.)

 

[John.g]

Depends on how much dynamic head you have to play with. 35ft of 1ins pipe will lose 0.23M at a flowrate of 20LPM, 3/4ins will lose 0.93M. or if available head very low and you require a very small pipe loss, a 3/4ins pipe (35ft) will only give a flowrate of 9.4LPM for the same loss of 0.23M which will give a flowrate of 20LPM using 35ft of the 1ins pipe.

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[John.g]

Looking at that again in the overall context of mains pressure in Bar.
1235ft of 1 ins piping flowing 25LPM will have a pressure drop of 1.22bar and 1200ft of 1ins piping + 35ft of 3/4ins piping flowing 25LPM will have a pressure drop of 1.32bar so practically no difference so shouldn't create a problem if 35ft of 3/4ins pipe is installed.

 

[cscjjd]

J: Great and thanks for both - especially the second explanation. I will get back to you if I need a third