HElp with Pipe Sizing

[orthopod]

Plumbing is going in soon. Our pool is now about 40,000 gallons. Pic attached of an aereal shot.

2 3HP VS pumps, 1 for the pool/Spa, 1 for the waterfall, a very large 30-40 ton water feature up on a raised wall.


Just talked with the pool builder, he was thinking 3 inch suctions x 2 for the waterfall, 2 inch returns x 4 to the waterfall.

He was planning 2 inch returns for the pool x 4 (8 total returns 2 on each pipe), 2 2 inch suctions

He was planning 2 inch suction from Spa and 1 1/2 returns.


Im thinking we need to go 3 inch suctions from pool, 2 inch returns are fine.

Im thinking 3 inch suction from spa, and 3 inch return that tapers down to 1 1/2 at spa......


Ive been reading and reading and its a bit confusing....Guess thats why Im not an engineer

 

[mas985]

For proper hydraulic balance, the return pipe head loss should be more than the suction side. So I would agree that you want at least 2.5" suction side plumbing given there are only two runs vs the 4 runs on the return side. 4x2" returns are equivalent to 1x3.67" pipe while 2x2.5" are equivalent to 1x3.29" so a better balance but 3" wouldn't hurt either.

As for the spa, depending on the design, that could be way too small of pipe to uses. Spas generally require very high flow rates and should have very low head loss so they operate properly. How many jets do you have and what is the flow rate requirement for each of the jets?

 

[ctrav]

I don’t have your answer but two things I do...

1 More than one person has the answer on this forum...they are so smart!
2 Your pool is going to be awesome in an awesome setting!

 

[orthopod]

mark-
e are deciding on either the waterways therapeutic jets, or jets with a minimum requirement of 15gpm....

Ive ready the Stickys in this forum page about 50 times and I think I am starting to understand more....Im becoming obsessed about building an efficient pool that works great.....

this forum has been awesome.
w

 

[jimmythegreek]

The one problem w the 3" lines from the pool is they end up in a 2" pump inlet and outlet so on long runs u loose the benefit. My opinion is u rly only need about 5 returns back to pool and a 2" manifold to 1.5" home runs will work great eyeballs r only 3/4 holes. 2" suction w 2 home runs is perfect it's what I have I run 14psi at full power on my 3hp vsp. The spa needs the bigger pipe it's short runs u can move water faster just size ur jets as said above. The waterfall if it's a slow rolling waterfall doesn't need as much water as u think. Depends on how it's laid out and what the vision is. If u want high volume u want a waterfall pump

 

[mas985]

The one problem w the 3" lines from the pool is they end up in a 2" pump inlet and outlet so on long runs u loose the benefit.

Totally untrue. The benefit still exists. Head loss is dependent upon the length of pipe and the diameter. The transition back to 2" adds very little head loss to the system.