Decrease pressure and re-plumbing

Jump to latest Follow Reply
V

Vafa

Member
Apr 30, 2021
6
Dallas, TX
Pool Size
12500
Surface
Plaster
Chlorine
Liquid Chlorine
I had to read some study on how to design and build dust collector system for my workshop garage and I thought since the water obeying same law as air, so I may be able to improve water flow on my pool by bypassing the heater on return line(Skipping seven elbow) and replace two 90 degree elbows with two 22.5 degree connection.
So I did this experiment with some $1~$3 connection, one $14 2" ball valve, 2' pipe. Fitting those non-90 degree connection in 3 dimensions and different height was a big challenge and close to impossible.
Took me two afternoon and tree trip to home store to make it happen.
Before:
IMG_20220403_135951~2.jpg
IMG_20220403_135846.jpg
After:
IMG_20220512_091052.jpg

I have about 10 psi less on filter gauge with the new path and this 10 psi is gold for me because even after a week without backwash the gauge read 25 psi and I visually guess it's at least twice water movement on my pool.
Fitting this new connection between two fixed side wasn't easy job specially with 5 second window for glue from applying to hardening.
I messed on point and had to cover it with cutout from 4" pipe to stop the leak.
The high water flow that I see on my lion mouth, vacuum and spa fountain is worth the effort.
I just wonder why the pool builders don't care for this basic physic on design it.
I can explain it move if the picture is not clear what I'm done.
 
Last edited:
I commend the creativity. However… I can’t read the markings on the pipe, but several of the fittings (including the wye & 22s) look to be PVC-DWV (drain/waste/vent) fittings and not Schedule 40 PVC. DWV fittings are not pressure rated and only designed for low-pressure (drain/vent) systems.

I have never seen those fittings in Schedule 40 PVC; if they exist they aren’t commonly stocked anywhere I shop. That’s likely why you haven’t seen other systems designed this way.
 
magiteck said:
I commend the creativity. However… I can’t read the markings on the pipe, but several of the fittings (including the wye & 22s) look to be PVC-DWV (drain/waste/vent) fittings and not Schedule 40 PVC. DWV fittings are not pressure rated and only designed for low-pressure (drain/vent) systems.

I have never seen those fittings in Schedule 40 PVC; if they exist they aren’t commonly stocked anywhere I shop. That’s likely why you haven’t seen other systems designed this way.
Click to expand...
I live in DFW and found them in Lowe's but I know Home Depot carry them too. I checked Lowe's at Neenah, Wisconsin for you and I see they got them in stock. So it is "commonly stocked anywhere".
This is the link for some of the SCH40 2" pipe and connection.
As you see in below screenshots, All of this are SCH40. So all are made for working under pressure.

Screenshot from 2022-05-12 17-48-26.pngScreenshot from 2022-05-12 17-47-32.pngScreenshot from 2022-05-12 17-46-50.pngScreenshot from 2022-05-12 17-54-26.pngScreenshot from 2022-05-12 17-46-39.pngScreenshot from 2022-05-12 17-46-22.pngScreenshot from 2022-05-12 17-45-59.png
 
  • Like
Reactions: DBswim
Vafa said:
I live in DFW and found them in Lowe's but I know Home Depot carry them too. I checked Lowe's at Neenah, Wisconsin for you and I see they got them in stock. So it is "commonly stocked anywhere".
This is the link for some of the SCH40 2" pipe and connection.
As you see in below screenshots, All of this are SCH40. So all are made for working under pressure.

View attachment 409817View attachment 409818View attachment 409819View attachment 409823View attachment 409820View attachment 409821View attachment 409822
Click to expand...
That’s interesting, thanks for posting. I’m not used to seeing such shallow sockets on pressure pipe.

I checked some of the items on Lowes site and it gets even more interesting. Take the 90, item 00304 0800. Here’s what it states in the description:
21F27C82-9830-487E-BF32-55DCCBEF6040.jpeg

Same disclaimers listed on the wye.
 
  • Like
Reactions: Vafa
I think @magiteck is right. Check out this post/thread...

Schedule 40 DWV

Reading through these forums its been mentioned to use Schedule 40 PVC and avoid DWV for above ground pool plumbing. But what if something is both DWV and Schedule 40 (see links bellow)? Could these be used...
www.troublefreepool.com www.troublefreepool.com
 
  • Like
Reactions: Vafa
ASTM D2466 is the correct rating for pressure fittings.

ASTM D 1785 is the standard for pressure rated pipe.

ASTM D 2665 is the standard for DWV pipe and fittings.

A pipe can be dual rated ASTM D 1785 and ASTM D 2665, but it has to say ASTM D 1785 if it's going to be used for pressure.

ASTM D2665-20
An ASTM designation number identifies a unique version of an ASTM standard.
D2665-20
D = Miscellaneous Materials
2665 = assigned sequential number
20 = year of original adoption (or, In the case of revision, the last year of last revision)

Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Drain, Waste, and Vent Pipe and Fittings​

 
  • Like
Reactions: Vafa, magiteck and Rancho Cost-a-Lotta
The use of the term schedule 40 is likely an error for the fittings from Lowe's.

In any case, verify that the fittings are listed as ASTM D2466 and not ASTM D2665.


Below, you can see sweeps rated as ASTM D2466.

1652409431133.png
ASTM D2466-21
An ASTM designation number identifies a unique version of an ASTM standard.
D2466-21
D = Miscellaneous Materials
2466 = assigned sequential number
21 = year of original adoption (or, In the case of revision, the last year of last revision)

Standard Specification for Poly(Vinyl Chloride) (PVC) Plastic Pipe Fittings, Schedule 40.​

 
Last edited:
  • Like
Reactions: Vafa and magiteck
Thanks for clarify. I was only looking for the SCH40 in the time of picking this connections.
But i will take the risk and not going to redo it now. I will count on pump thermal switch in case of major leakage during a time that nobody is in home and water go below the skimmers. Sound like a plan?
 
Vafa said:
I had to read some study on how to design and build dust collector system for my workshop garage and I thought since the water obeying same law as air, so I may be able to improve water flow on my pool by bypassing the heater on return line and replace four 90 degree elbows with 3 of 22.5 degree connection.
Click to expand...
I doubt you will see much of a change. The head loss difference is going to be immeasurable.

Also, less head loss results in higher flow rates but also higher energy use unless you can reduce RPM.

Not worth the effort IMHO.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Vafa said:
Thanks for clarify. I was only looking for the SCH40 in the time of picking this connections.
But i will take the risk and not going to redo it now. I will count on pump thermal switch in case of major leakage during a time that nobody is in home and water go below the skimmers. Sound like a plan?
Click to expand...
Pump thermal switch? It looks like you have a single-speed motor. They have a thermal overload in them, but a pump running dry won't trip it. A locked rotor, jammed impeller-yes, virtually instant overload.
That's a lot of water and equipment and property (neighbor's yard?) to trust to plumbing not designed for the use.
 
Last edited:
mas985 said:
Not worth the effort IMHO.
Click to expand...
I went from 11 x 90' elbow and a heater to 2 x 45' , 2 x 22.5' and one 90' elbow.
As I said my goal wasn't energy consumption and it was better circulation. My pool cleaner is functioning now because I have reduction in head loss.
How less head loss results in higher energy use !?

1poolman1 said:
Pump thermal switch? It looks like you have a single-speed motor. They have a thermal overload in them, but a pump running dry won't trip it. A locked rotor, jammed impeller-yes, virtually instant overload.
That's a lot of water and equipment and property (neighbor's yard?) to trust to plumbing not designed for the use.
Click to expand...

Yes, you are right about thermal overload, but even if my assumption about it getting hot when running without water is not true, my pool will not get drained even with suction valves set to 80% on cleaner, because it's not a lot of water loose when it just takes two minutes for the skimmer to start sucking air. When they suck air, it won't pump water from the cleaner either.

The water flow is amazing and the pressure is 15psi.
I wish I knew about the ASTM D2466 before doing it.
I just learn about another two more big thing that not mentioned.
One is my Pentair Mastertemp 400 has a automatic bypass system. So I am not saving any flow inside the heater.
Two, The discharge line on the pump shouldn't get any immediate connection that limit the flow. This is probably why they use three elbow on discharge line to filter.(below picture)
Screenshot from 2022-05-18 15-28-18.png Screenshot from 2022-05-18 15-37-01.png
Right before modification, left after. They could use only one elbow and move the pump back to don't go up and than down but probably they don't put an elbow right by the flange.

But it's OK, I called it experience! Not every body afford it. I did it for TFP :D
 
Last edited:
My original comment was referring to the fittings alone and to the original amount you had stated in your first post. There you said:
replace four 90 degree elbows with 3 of 22.5 degree connection.
Click to expand...
This type of replacement will not affect head loss or flow rates much.

Vafa said:
I went from 11 x 90' elbow and a heater to 2 x 45' , 2 x 22.5' and one 90' elbow.
As I said my goal wasn't energy consumption and it was better circulation. My pool cleaner is functioning now because I have reduction in head loss.
Click to expand...
This is a completely different story.

A typical 2" plumbing pool has the equivalent pipe length (include pipe, fittings, valves, heaters, filters, skimmers, eyeballs and everything else that touches water) of about 600' of 2" pipe. Each 90 has the equivalent head loss of 6' of pipe, each 45 or sweep 90 is about 3' of 2" pipe. So you are replacing about 66' of equivalent pipe with about 18' of equivalent pipe so reducing the equivalent pipe by about 48' of 600' or a little less than 10% in head loss. However, if you are removing the heater as well, that removes 150' of equivalent head loss out of the same 600', so combined, that is about 1/3rd so yes that combined will make a difference. Most of the difference is due to the heater bypass.

How less head loss results in higher energy use !?
Click to expand...
For single speed and two speed pumps, this is always true. Energy use is proportional to the Head Loss x Flow Rate. But a pump's head curve is such that when head loss decreases, flow rate increases faster so energy use goes up. With a VS pump, one can lower the RPM such that the flow rate is the same between before and after the reduction in head loss. Only then does the energy use reduce.
 
  • Like
Reactions: Vafa
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply