This is true, just need to note that when the resistance is already very small, 40% of “very small” is still pretty close to very small.
Will Streamlining my pool plumbing increase efficiency
- Thread starter danwas44
- Start date
- May 3, 2007
- 18,067
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
ChatGTP learns from the internet and unfortunately, the internet has some wrong information.
This part is true.
These equivalent lengths are not reflective of most internet sources regarding head loss of fittings so I am not sure where they got the info for this but I have never seen values that high for those fittings.
Head loss is dependent on geometry and manufactures tend to have unique geometry so it really depends on the exact fitting used.
A while back I did some simulations on fittings that manufactures had CAD drawings on so that I could accurately model the fitting as best as possible:
Lasco 90 - 6' Equivalent Length
Nibco 90 - 5' Equivalent Length
Sweep 90 1" Curve - 3' Equivalent Length (note that larger radii will have less head loss)
True
Key Points:
- A sweep elbow has a larger radius, which reduces turbulence and friction loss.
A sweep as well as any fitting has a male-female connection. It is the short radius which causes the higher head loss.
Rarely true for pool plumbing. Most of the head loss in a typical pool plumbing tends to be in other places than elbows (e.g. filter, heater, valves, etc). I did a model of my own plumbing to see what the effect of replacing the ELL 90s on the pad with sweeps, 7-90s total:
Full Speed Results:
2" Ell 90s Operating Point: 31.15' Head, 65.74 GPM, 983 Watts
2" Sweep 90s Operating Point: 30.70' Head, 66.32 GPM, 985 Watts
40% Speed Results (normal speed):
2" Ell 90s Operating Point: 4.98' Head, 26.30 GPM, 85.97 Watts
2" Sweep 90s Operating Point: 4.91' Head, 26.53 GPM, 86.13 Watts
So not much different and not really worth the effort.
Plus many systems like mine only allow 5% increments in pump speed so you may not achieve any energy savings by going with sweeps unless you can improve the flow rate by at least 5% and lower the RPM by 5%.
Note: This is incorrect.
See later posts.
See later posts.
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- May 3, 2007
- 18,067
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Those are much less that what you see in typical equivalent length tables.
This table comes closest to the simulations that I ran:
www.engineeringtoolbox.com
This table comes closest to the simulations that I ran:
PVC Pipes - Equivalent Length and Pressure Loss in Fittings
Minor loss in PVC and CPVC fittings expressed as equivalent length of straight pipe.
www.engineeringtoolbox.com
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- Jul 21, 2013
- 65,062
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Data wars! Love it!
Why don't you data guys put in perspective those numbers against the equipment head of a Pentair FNS Plus 60 sqft DE filter, AcuaComfort ACT 1250 Heat Pump, and Caretaker 5 port in-floor cleaning system?
- May 3, 2007
- 18,067
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
Last edited:
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How to select pool equipment - Further Reading
www.troublefreepool.com
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Attachments
I agree that the numbers are probably not accurate.
Seems odd because they come from a reputable company.
Thanks everyone for the analysis. I'll report back when i open my pool, I live in Mass so not for a few more weeks. After the pool is up and running and water is balanced, I'll run the exact same speeds and see what I get.
This is a newer document.
The sweep numbers still seem low, but more realistic.
www.westlakepipe.com
ENERGY EFFICIENT SWEEP ELLS
Solvent Weld
©2025 Westlake Pipe & Fittings All rights reserved PS-PS-002-US-EN-0325.1
The sweep numbers still seem low, but more realistic.
www.westlakepipe.com
ENERGY EFFICIENT SWEEP ELLS
Solvent Weld
©2025 Westlake Pipe & Fittings All rights reserved PS-PS-002-US-EN-0325.1
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Using an 8 feet per second velocity (84 gpm in 2" PVC pipe), the head loss per 100 feet of pipe is about 10 to 12 feet, which is about 0.10 to 0.12 feet of head loss per foot of PVC pipe.
A regular 90 at 5.75 feet of pipe (equivalent) is 5.75 x 0.11 = 0.6325 feet of head loss.
A Sweep 90 at 2.10 feet of pipe (equivalent) is 2.10 x 0.11 =0.231 feet of head loss.
However, the flow rarely needs to go above 40 gpm for a residential system, so that is a velocity of 3.9 feet per second.
That is 0.028 feet of head loss per foot of 2" pipe.
A regular 90 at 5.75 feet of pipe (equivalent) is 5.75 x 0.028 = 0.161 feet of head loss.
A Sweep 90 at 2.10 feet of pipe (equivalent) is 2.10 x 0.028 =0.0588 feet of head loss.
So, you are saving about 0.1022 feet of head loss per sweep 90 vs. a regular 90.
Even at 10 sweep 90s, that is only 1.022 foot of head loss, which is pretty insignificant.
1.022 foot of head loss is 0.44 psi.
Choosing the correct pipe size is very important for high-efficiency plumbing.
Ideally, it is best to keep suction pipe velocity below 6 ft/sec and return pipe velocity below 8 ft/sec.
This helps prevent suction side issues such as entrapment and air leaks.
Also, it is a good idea to have a separate suction line from each skimmer and/or main drain pair from the pool to the pump to isolate suction lines if necessary.
The water velocity in a pipe is determined by its size and the flow rate through it.
Below is a table of standard pipe sizes and the recommended flow rates for two different velocity specifications.
www.engineeringtoolbox.com
A regular 90 at 5.75 feet of pipe (equivalent) is 5.75 x 0.11 = 0.6325 feet of head loss.
A Sweep 90 at 2.10 feet of pipe (equivalent) is 2.10 x 0.11 =0.231 feet of head loss.
However, the flow rarely needs to go above 40 gpm for a residential system, so that is a velocity of 3.9 feet per second.
That is 0.028 feet of head loss per foot of 2" pipe.
A regular 90 at 5.75 feet of pipe (equivalent) is 5.75 x 0.028 = 0.161 feet of head loss.
A Sweep 90 at 2.10 feet of pipe (equivalent) is 2.10 x 0.028 =0.0588 feet of head loss.
So, you are saving about 0.1022 feet of head loss per sweep 90 vs. a regular 90.
Even at 10 sweep 90s, that is only 1.022 foot of head loss, which is pretty insignificant.
1.022 foot of head loss is 0.44 psi.
Choosing the correct pipe size is very important for high-efficiency plumbing.
Ideally, it is best to keep suction pipe velocity below 6 ft/sec and return pipe velocity below 8 ft/sec.
This helps prevent suction side issues such as entrapment and air leaks.
Also, it is a good idea to have a separate suction line from each skimmer and/or main drain pair from the pool to the pump to isolate suction lines if necessary.
The water velocity in a pipe is determined by its size and the flow rate through it.
Below is a table of standard pipe sizes and the recommended flow rates for two different velocity specifications.
| 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 |
Hazen-Williams Water Flow Formula: Head Loss, Data, Charts & Calculator
Friction head loss (<i>ft<sub>H2O</sub> per 100 ft pipe</i>) in water pipes can be estimated with the empirical Hazen-Williams equation.
www.engineeringtoolbox.com
Sweep 90s are more efficient and are preferable to regular 90s.
Whenever possible, it is preferable to give some straight pipe before a 90, but it is not necessary, in my opinion.
In my opinion, pipe size is vastly more important than whether you use regular 90s or Sweep 90s.
Whenever possible, it is preferable to give some straight pipe before a 90, but it is not necessary, in my opinion.
In my opinion, pipe size is vastly more important than whether you use regular 90s or Sweep 90s.