Main Line Sizing

[Killawhale]

So I am building a shop/ apt, apt is 2bdrm 2 bath, and in the future building a 3bdrm/2.5 bath house on same property. I have asked around locally and get so many different answers. I want to plan for the future so what size main should i use. My initial idea was 2in to a Y then 1 1/4 to house and building. From street to Y is 900ish feet and 450+ to building and house site. City has 3/4 connection and 70+ psi of pressure. Thank you in advance

 

[JoeJee]

I would be interested in the answer. Assuming no elevation change and 500’ you would be good with 2” but you have much more than that to go. 2” copper is also better flow than 2” Pex or other Plastic pipe.

 

[Sponsor]

 

[Terry]

This chart is a start, they also make them for more distance.

 

[John Gayewski]

There aren't really Ys for water piping. A tee is generally I think what your after. Water is calculated in fixture units. So you'd need a drawing that shows how many and what fixtures your planning to use. Are you saying that from the provided 3/4"connection your roughly 1350 feet away?

 

[Killawhale]

JoeJee I'd love to do copper but at about 300 per 20 ft its just not in the budget. Thank you Terry. I have been trying to apply those charts to this problem. John I haven't found any Ys but was trying everything to maintain flow and pressure. Yes both structures will be 1450-1500ft from city tap.

 

[John Gayewski]

The pressure loss on 2 piping is very low. I think I'd go with it. I'm thinking your 3/4 connection won't be sufficient.

The pressure loss on 1.25" is low but given the distance I'd go 2"

 

[Killawhale]

I have requested a 1 in meter from the city. Probably go with 2in HDPE

 

[Reach4]

I would be interested in the answer. Assuming no elevation change and 500’ you would be good with 2” but you have much more than that to go. 2” copper is also better flow than 2” Pex or other Plastic pipe.

Two-inch SIDR polyethylene pipe has better flow than 2 inch copper, and costs a lot less.

 

[John Gayewski]

I have requested a 1 in meter from the city. Probably go with 2in HDPE

2"pipe looses about 0.4ft of head at 30gpm every 100 feet. 1.25" pipe looses about 8 feet of head at 30 gpm every 100 feet

30 gpm is a high side guess at about how much flow you'll need.

With a1" meter you'll lose another 6.5psi at 30 gpm

 

[John Gayewski]

If you ran 1.25 you'd lose about 60psi at 30 gpm 1400ft including the meter. (edit I did my head conversion backwards it's actually about double [120psi]) These are rough estimates

 

[Reach4]

http://irrigation.wsu.edu/Content/Calculators/General/Pipeline-Pressure-Loss.php is a simple pressure drop calculator.
http://www.pressure-drop.com/Online-Calculator/ is a more complex calculatorl

I think 15 gpm would be a good flow for what you describe.

https://www.menards.com/main/search.html?sf_categoryHierarchy=&search=sidr shows the type of pipe I would use. I would go for at least 160 psi rating. Do not pull pipe tight, but instead snake it in the trench to allow for thermal contraction.

 

[John Gayewski]

http://irrigation.wsu.edu/Content/Calculators/General/Pipeline-Pressure-Loss.php is a simple pressure drop calculator.
http://www.pressure-drop.com/Online-Calculator/ is a more complex calculatorl

I think 15 gpm would be a good flow for what you describe.

https://www.menards.com/main/search.html?sf_categoryHierarchy=&search=sidr shows the type of pipe I would use. I would go for at least 160 psi rating. Do not pull pipe tight, but instead snake it in the trench to allow for thermal contraction.

That's two hose bibs