Elbow use in pool plumbing

[NewPumpGoingIn]

When making a 90 degree turn in the plumbing, is it better to use one 90 degree elbow or two 45 degree elbows? Is there any data to support one versus the other in providing the best flow through the pipes? It would seem that a gentle curve would be better than a sharp turn, so to speak.

[czechmate]

Either way is fine. It is water afterall.
It makes difference in pumping crude oil with impurities and friction in a metal pipelines.
The less connections means less potential leaks. There is also small 90 degree fitting available in plumbing shops.
I would not be concerned as 99 percent of plumbers are not either.
The only thing that may be potentialy an advantage is to add a "compensator" in a runs, for likelihood of a pool or ground settling. (Can be done with fitting or by bowing the pipe on longer runs).I had not done either and have not had a problem in Dallas black clay.
BTW, never lay large PVC SCH40 in very hot weather on longer runs without covering with dirt immediately. Hot weather also impedes proper gluing.
Evening cooling may pull fittings apart. (Have seen it many times on long electrical runs).

[TSH Tech]

Well, you may want to consider a few factors if you are concerned about water flow. If you are plumbing pool equipment, a 90 sharp elbow with a size of 1 1/2 inch pipe, is equivalent to 7 feet of straight pipe. A 2 inch 90 degree sharp elbow is equivalent to 8 feet of straight pipe.
What does this all mean? In water flow terms, it's the amount of friction that slows down water as it passes through the pipe. Two 45's wouldn't hurt if you have space to plumb, they do have a lower water friction coefficient. If space is of concern, Waterway Plastics makes a sweeping 90 PVC coupler Sch. 40 called an Ells 90 degree PVC sweep.

I can see this being applicable to a water fountain where flow is of great importance.

[kiwi norman]

Czechmate can you email me kiwipool@vodafone.net.nz

Norman.

[mas985]

2 45s have about the same head loss as a single 90 so it really shouldn't make much of a difference. When you include the glue joints, it is usually worse. However, if you really want to save on head loss, the most cost effective way is to increase the pipe diameter. Increasing from 2" to 2.5" reduces head loss by over 60% for the pipe and fittings. Far better than fiddling with the fittings.

[Brandotheplumber]

Hello
I am a master plumber and have plumbed in a few pools. I am working on one that I had to stack some 90’s to make the pipes come out straight. First I hate fittings because I hate leaks. So I was torn was I doing the right thing… Am I loosing head??? Do I have more chance at a leak just because it’s a 90??? I think to my 24 years of plumbing and doing radiant heat. The first thing I think about is that the eyeball on the end of the jet reduces down to 1/2” so why should I worry?
In the end I agree with czeckmate. The use of fittings are important force bending pipe makes cracks. Less fittings the best 2 45’s no way unless it’s a waste line. Leaks are going to be your no 1 problem. Just my 10cents here is a chart for you https://www.pmmag.com/articles/88006-eq ... nthaler-pe
Brando

[Teapot1]

The first thing I think about is that the eyeball on the end of the jet reduces down to 1/2” so why should I worry?
In the end I agree with czeckmate. The use of fittings are important force bending pipe makes cracks. Less fittings the best 2 45’s no way.

Your first point is of course correct in that the stupid pool industry generally hasnt a clue. My sytems and installs balance (enlarge ) the return fitting holes to equal the cross sectional area of the pipe divided by the number of returns obviously. However with powerful pumps this would almost certainly lead to cavitation at the pump so another good reason to use a variable speed pump. Standard setups with 1/2" holes just creates more dynamic head and larger electricity bills.

Depending on the system 2 x 45's can often produce higher flow due to less resistance as seldom are there just one 90 bend so they all add up. As you reduce the speed and power of the pump the flow becomes more important so long radius bends and 2x 45's are relevant.
The biggest loss is still the filter, manufacturers overstate the flow you are likely to get by x2 to try and outsell the competition, I know this from flow testing actual figures from pools I have worked on, its the first test I do.
Gluing joints, do it right and no leaks, these are low pressure open systems.