180 degree bend from pump outlet?

[Homerraas]

Hi all,

I will be installing a Intelliflo in 2 weeks time at the house in France.

What is the best length from the outlet of the pump before a 180 down, I understand it's less then desirable to do an 180 for the flow but that is what i have and don't feel like ripping the floor open.

The inlet has to be 20" straight when entering the pump (2" line) , that i can make without a lot of hassle.

Here a picture of the old setup (still working) pump (1.5hp single speed 90gpm)

Any input greatly appreciated!

 

[mas985]

Bends simply add head loss and their location (before or after the pump) really doesn't affect the head loss that much to be overly concerned about.

Some manufactures will recommend a 5D rule before the pump basket but CFD simulations that I have run show very little difference in the impeller inlet velocity gradients so the difference in impeller loading should be very similar.

Pump Basket 90 Location - Google Drive

drive.google.com

Also, I have a spa jet pump that is plumbed very similar to your old pump and it has been running for 18 years without incident. I wouldn't get too worked up about it.

 

[ajw22]

What is the best length from the outlet of the pump before a 180 down, I understand it's less then desirable to do an 180 for the flow but that is what i have and don't feel like ripping the floor open.

Does not matter. You have two 90's and running a VS pump at low speeds it does not matter.

The inlet has to be 20" straight when entering the pump (2" line) , that i can make without a lot of hassle.

10 inches is all you need.

 

[JamesW]

If you keep the water velocity below 6 feet per second, it is not a big deal.

Above 6 ft/sec the main issue is noise caused by turbulence.

Noise increases exponentially like head loss.

So, if the flow is double, the head loss and noise increase by about 4 times.

Sweep 90s reduce turbulence, head loss and noise.

You can use a 2.5" pipe and fittings instead of 2" pipe to reduce velocity.

The Intelliflo3 takes either 2.5" pipe or a 3" fitting.

The regular Intelliflo uses 2" fittings, but you can use a reducer bushing to upsize to 2.5".

Pipe Size and Flow Rates.​

You want to keep the water velocity below 6 ft/sec on the suction and below 8 ft/sec on the pressure side of the pump.[7]

Pipe Size	6 ft/sec	8 ft/sec
1.5"	38 GPM	51 GPM
2"	63 GPM	84 GPM
2.5	90 GPM	119 GPM
3.0"	138 GPM	184 GPM
4.0"	235 GPM	312 GPM

You can use sweep 90s if you want.

https://assets.speakcdn.com/assets/1824/sweeps2013.pdf

https://assets.speakcdn.com/assets/2683/energy_efficient_sweep_els_specification_2020.pdf

Equipment Pad Best Practices - Further Reading

www.troublefreepool.com

 

[JamesW]

You can use two Slip x Slip or a slip x slip and a slip by spigot for a really tight turn.


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[JamesW]

What flow rates do you expect to need and for what purpose?

 

[1poolman1]

Hi all,

I will be installing a Intelliflo in 2 weeks time at the house in France.

What is the best length from the outlet of the pump before a 180 down, I understand it's less then desirable to do an 180 for the flow but that is what i have and don't feel like ripping the floor open.

The inlet has to be 20" straight when entering the pump (2" line) , that i can make without a lot of hassle.

Here a picture of the old setup (still working) pump (1.5hp single speed 90gpm)

Any input greatly appreciated!

While its not best practice to have the plumbing as in your picture, it really won't cause any issues, especially with a VSP and slow water flow. You only need about 10" in front of the pump for best hydraulics. But then there are many, many pools plumbed as in that picture. It can make for a bit of noise at full speed, but again, with slower flow it shouldn't be an issue

 

[Homerraas]

What flow rates do you expect to need and for what purpose?

It's the pool pump, filter can "handle" 70GPM doubt I will ever go that high pool is 22k

It's the Intelliflo 2 as the 3 gives me no benefits in current setup and connectivity.

While its not best practice to have the plumbing as in your picture, it really won't cause any issues, especially with a VSP and slow water flow. You only need about 10" in front of the pump for best hydraulics. But then there are many, many pools plumbed as in that picture. It can make for a bit of noise at full speed, but again, with slower flow it shouldn't be an issue

So there is no length needed from the outlet? I can more or less do the same as in the picture? outlet, few inches and 2x 90 degree bends?

Does not matter. You have two 90's and running a VS pump at low speeds it does not matter.



10 inches is all you need.

View attachment 548623

Yeah sorry 10" not 20" the conversion from CM to inch got screwed up LOL

 

[ajw22]

So there is no length needed from the outlet? I can more or less do the same as in the picture? outlet, few inches and 2x 90 degree bends?

Correct.

 

[1poolman1]

Hi all,

I will be installing a Intelliflo in 2 weeks time at the house in France.

What is the best length from the outlet of the pump before a 180 down, I understand it's less then desirable to do an 180 for the flow but that is what i have and don't feel like ripping the floor open.

The inlet has to be 20" straight when entering the pump (2" line) , that i can make without a lot of hassle.

Here a picture of the old setup (still working) pump (1.5hp single speed 90gpm)

Any input greatly appreciated!

While it is better to have a bit of straight pipe before you start turning the water, especially with two 90s that close, it won't really cause any issues as is with a VSP running slower waterflow. Or use two sweep 90s as JamesW mentioned. You're going to be moving the pump a bit anyway as the Pentair is very different from your existing pump. You can make a bit of room for the plumbing that way.

 

[mas985]

In my opinion, and the simulations back this up, there is virtually no difference in hydraulic performance with a 90 right before the pump basket and one 5D away.

The 5D requirement is a holdover from the water distribution industry. They require that for very large pumps where the inlet pipe goes straight into the pump impeller inlet without a pump basket where the velocity gradients are very steep and can cause unequal loads on the impeller. However, for residential pumps that have a pump basket and much lower HP pumps, the 5D requirement makes no difference.

However, there are other reasons to have straight pipe before/after the pump and the best reason is to have some real estate to work with for the eventual replacement of the pump.

 

[Homerraas]

While it is better to have a bit of straight pipe before you start turning the water, especially with two 90s that close, it won't really cause any issues as is with a VSP running slower waterflow. Or use two sweep 90s as JamesW mentioned. You're going to be moving the pump a bit anyway as the Pentair is very different from your existing pump. You can make a bit of room for the plumbing that way.

LOL really? they "look" the same to me. The motor is private label from some French company, the rest is Pentair as I ordered gaskets and a O ring for the filter last year. My Quad DE filter is also labeled ExelQuad as private label