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Pipe size for inground pool

Posted by highlt (My Page) on
Sat, Mar 15, 08 at 0:02

Hi

I'm in the process of contracting a pool that is 20x48 with an average depth of 5.75. The pool will include an 8 ft deep end and an 3.5 ft shallow. The shallow end will be 24 ft in length and the other half will be the deep end.

The contractor states using a 1.5 HP Hayward Super Pump, Hayward 240t filter and 1.5 inch pipe will be sufficient to keep the pool clean in a 10 - 12 hour turnover cycle.

My question is this. If a 1.5 inch PVC pipe can only take 42 GPM shouldn't the pool require a 2 inch pipe? They continually state that the pool will be fine with 1.5 inch pipe and state the following reasons for discouraging me away from 2 inch pipe.

1. more surface area in the pipe makes the pressure flow into the pool less, thus less pressure means less movement of water and more time for water to get back to the skimmers.

2. Any automatic cleaner you use will run slower and may stop and go and will need an upsize adapter to 2"

3. all inlets and outlets in the pool wall and floor are factory cut for 1 " so an extra $600 will be added to the price to up size these openings.

I want to ensure 1.5 inch pipe is ok to use for a 20x48 pool because from what i have read a 42 GPM flow rate is the maximum for this size pipe. Please help me. I'm not writing a contract until I get this issue resolved.


Follow-Up Postings:

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RE: Pipe size for inground pool

There is really one simple answer. Your pool builder is an idiot.........


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RE: Pipe size for inground pool

Sounds like your builder needs some education. Encourage him to sign up for the construction school put on by the Genesis 3 Design Group in Atlanta in October.


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RE: Pipe size for inground pool

your builder is out of the mindset of the 60's. he must be oldschool with absolutely no time spent in the classroom to learn or understand hydrolics.He is doing you no favors by insisting on small pipe,and what you save now will cost you month after month after month after month...need I go on!!


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RE: Pipe size for inground pool

That's a big pool (42,000 gallons). At 42 gpm it'll take 17 hours to turn the water over once. Maybe they're coming out of the pump with 2" and then splitting into 1-1/2" pipe for the runs?


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RE: Pipe size for inground pool

Depending on the slope of the pool floor, you've got anywhere from a 34K-42K gallon pool.

If 34K, a turnover in 12 hours requires 47 GPM. If 42K, 59 GPM is needed. So you've just exceeded the max flow on 1.5" pipe unless you extend the filtering several more hours... assuming there is one suction and 1 return.

The reality is if you have multiple suction pipes, you approximately double the max flow rate. If the skimmer and drain are piped separately (i.e. you'll have two 1.5" pipues pulling water from the pool), your pool can flow about 84 GPM.

Will 1.5" work? Sure, but you'll introduce a lot extra pressure in the system, thus reducing overall efficiency, and increasing electric comsumption.

I'm with the others here... you need 2" plumbing. Your plumbing will be more efficient. High efficiency means a lower electric bill.

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I'll address your PB's raeasoning:
Quote: "1. more surface area in the pipe makes the pressure flow into the pool less, thus less pressure means less movement of water and more time for water to get back to the skimmers."

They put a nozzle on the return pipes inside the pool, that is why you get a high pressure stream back into the pool. Nozzle's, because they reduce flow, increase pressure. My last pool had 2" pipes and 1.5 HP pump. No issues.

Quote: "2. Any automatic cleaner you use will run slower and may stop and go and will need an upsize adapter to 2" "

My last pool had 2" pipe and 1.5 HP pump. Had a Hayward Navigator suction-type cleaner. Worked like a charm.

Quote: "3. all inlets and outlets in the pool wall and floor are factory cut for 1 " so an extra $600 will be added to the price to up size these openings."

This just sounds like the company making the panels never upgraded, so they want to stick you for $600.


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RE: Pipe size for inground pool

Guys I appreciate the feedback. Not sure what to do about letting this person build my pool now. They have been buildings pools for 31 years but it's ashamed I have to do this kind of home work.


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RE: Pipe size for inground pool

Bottom line question:

Does 1.5 inch PVC pipe only support 42 GPM? I believe 2 inch supports 62 GPM.

Thanks
TErry


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RE: Pipe size for inground pool

You can move 150 gpm through a 2" pipe, but it will take about 90 psi to do so,.

7 feet per second or less typically seems ideal, and 2" at 7fps is 80 gpm.

The returns on our pools are 1 1/2 ", but you have multiple returns to carry the load of the filtration system. So you would split a 2" or 2 1/2" then reduce to the 1 1/2" at the pool wall.
2" returns are very difficult to find eyeballs for, and the eyeballs end up being 1" anyways which brings you to where you were before w/ the 1" pipe.


Think about this also.

2" pipe costs less than 20% more than 2" pipe. When we are talking about plumbing and entire pool the increase pipe size will costs less than $100 more


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RE: Pipe size for inground pool

I am paying $300 extra for my pool builder to upgrade from 2" to 2 1/2" pipes (for each individual run) on a 28K or so gallon pool. I expect to have a very short return on my investment due to the energy savings becasue of much lower resistance (2 1/2" has about a third of the dynamic head of 2" pipe in scenarios that apply to pools)


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RE: Pipe size for inground pool

Guys-

I'm still confused on exactly what can be run in 2 inch pipe. Is it possible for pump/filter, skimmers, inlets to use 2 inch pipe? Is there anything that can not use 2 inch. My builder is stating price will go up $600 for pipe and if I need 2 hp pump for 2 inch pipe and upsize filter too. Is it really worth all of this cost versus using the 1.5 inch?


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RE: Pipe size for inground pool

You can uss 2" pipe on a 1/2 hp pump. A 2hp pump should not use 2" pipe but 2 1/2" or 3" pipe.

There should be no "upcharge" for 2" pipe, as that is what every pool company should use on a pool over 5,000 gallons.

You can run a 1/2-1hp on 2" on 1.5-2.0 you either want multiple 2" pipes or upsized pipes.


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RE: Pipe size for inground pool

Don't mean to hijack, but

We will also be installing a 18x36 ig vinyl pool next month. No extra water features or spa..only solar heat.

What size pipe should the pb use if we have the intelliflo 4x160 variable pump (no exact hp per se). I have already told him we want 2in, and our pb also told us that would be an extra charge. Would we need 2 1/2"?


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RE: Pipe size for inground pool

You should get a 4x100. You have no need for 4x160.


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RE: Pipe size for inground pool

huh?

For the flow demands of your pool, and assuming they use 2-2" suctions 1 md 1 sk,

2" will be fine.


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RE: Pipe size for inground pool

An Intelliflo 4x100?? Can't seem to find any pump like that. Do you have a link?? Is it still variable?? With the solar and a SWG, we will need to have the water constantly flowing and was trying to do it in the most energy efficient way.

Our pool will have 2 bottom drains that will be tee'd, 2 skimmers (1 shallow end, 1 deep end) and 4 returns (more returns if needed based on step-n-spa and width of steps)

2" pipe still sufficient??


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RE: Pipe size for inground pool

I stand corrected it's a starite but its owned by the same company.See the link. The problem the manufactures are running into is liability for entrapment especially if you sell someone a pump that is way to powerful for the existing plumbing. Its a pentairpool.com/pdfs/intellipro4x160m.pdf
Your solar installer should be able to dial in the most efficient flow rate for the solar by check incoming and outgoing temps.
If you go with the large 160 you need to follow the instruction in the pentair installation guide even though you can set the flow lower to accommodate the smaller pipe it probably would never be an issue with two skimmers and dual main drains but inspectors go by the letter of the law.


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RE: Pipe size for inground pool

" but inspectors go by the letter of the law."

Does anyone here have inspectors looking at pump curves and verifying pipe sized?

With 2 skimmers and dual main drains and 2 -2" pipes the water is moving at 7fps @ 160gpm.


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RE: Pipe size for inground pool

Guys-

This is scaring the hek out of me. My pool will have 2 returns and one drain. The builder insists that 1.5 inch pipe, with a Hayward 1.5 pump and and Hayward 244t filter will work fine.

I'm still confused at how to calculate the turnover rate. The pool builder states since there are two returns you can double the GPM.

They stated they will put in what I want but it will cost at least $600 more and they do not feel I will gain anything for my money.

Is there anyone, that can show me how to calculate the proper size pipe for this 20x40 pool? I'm lost on how the returns etc. affect this.

My builder is recommending the following:
1.5 inch Rigid pipe
1.5 HP Hayward Super Pump
244t Hayward Filter
2 returns
1 main drain

They have been building pools since 1977 and state they have never put anything larger than 1.5 inch pipe in. I'm afraid to tell them to use 2 inch pipe and have them screw up the plumbing or sizing the filter, pump properly. I'm ready to go but will not sign contract because of my fear of the pipe. I'd love to be able to see the calculations to determine exactly what I need. If I need to supply more information, please tell me and I will provide what's needed. I really appreciate the help.


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RE: Pipe size for inground pool

Guys-

I have post above with questions too but below is what I really need to understand.

If I use two inch pipe, does the filter, pump, inlets and returns need to accept 2 inch pipe or can 1.5 inch reducers be used? If reducers are used is there any advantage to using 2 inch pipe?

I'm asking this question because the inlets on pool are 1.5, the filter and pump are 1.5. I would have to upgrade my pump to 2 hp to get a Hayward super pump with 2 inch connector and the filter would have to go to Hayward 270t2. If I can run 2 inch pipe and use reducers, then the only cost impact would be the move to 2 inch pipe versus upgrading to more expensive pump, filter and having to have inlets that are 2 inch.


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RE: Pipe size for inground pool

Pay him in 1977 dollars and see if he gets any smarter.

Seriously, where are you located and I'm sure many of us will know a good builder. Jeez, I don't even think the bait and switch guys - Blue Haven, etc., use 1.5" pipe on a pool that big.


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RE: Pipe size for inground pool

Guys-

This pool dealer is reputable and all the customers I've contacted are happy. I just don't take anyone's word for anything and I'm trying to ensure the best plumbing system. My friend has same pool with there recommended setup with no issues for 1 year but I'd prefer to setup
the most efficient way.

I have post above with questions too but below is what I really need to understand.

If I use two inch pipe, does the filter, pump, skimmers and returns need to accept 2 inch pipe or can 1.5 inch reducers be used? If reducers are used is there any advantage to using 2 inch pipe?

I'm asking this question because the inlets on pool are 1.5, the filter and pump are 1.5. I would have to upgrade my pump to 2 hp to get a Hayward super pump with 2 inch connector and the filter would have to go to Hayward 270t2. If I can run 2 inch pipe and use reducers, then the only cost impact would be the move to 2 inch pipe versus upgrading to more expensive pump, filter and having to have inlets that are 2 inch.


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RE: Pipe size for inground pool

Two returns? Is that enough? And to take the pump outlet up to 2" pipe then drop to 1 1/2" at the fittings going to the pool wall should'nt add much to the cost. Seems odd.


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RE: Pipe size for inground pool

Yeager-

I live in the cincinnati/dayton ohio area. Maybe I'm anal but I trying to learn the best way to plumb this pool and the number of skimmers and returns.


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RE: Pipe size for inground pool

Highlt

The math is easy,

20*48*5.5*7.5= 41,400 gallons.

To calculate the turnover you desire, I like 8-12 hours for a residential pool, let's use 12 for this equation as 12 is more prudent with a large pool such as yours.

41,400/12/60 = flow rate to achieve a 12 hour turnover.

In this case it is 57.50 GPM

Could we achieve this with 1 1/2" pipe? Sure but it will run 9.16 fps. 7 or less is what is desired on most swimming pool systems with 5 being ideal for suction lines.

I dont have any Hayward pump curves here nor do i care to, so I will use a whisperflo's curve for a baseline.

At 50' thd (head) a 1.5hp whisperflo will move 110 gpm. Now if we take this flow rate and put it through a 2" pipe we are looking at about 10fps at this flowrate. Which is over our 7fps. So we need either 2-2" pipes ~5fps, or 1 2 1/2" pipe which the water will move around ~7fps through.

It's impossible for me to calculate the tdh over the net and even that is a rough approximation.

Now getting to the filter. Typically the Maximum should be 20 Gpm per Sqft. The 244 is what I imaging you are getting is 3.14sqft that means that you can move a maximum of 62gpm through the filter which is far less that what we should expect from a 3/4hp pumps these days.

Long story short get a 1.0 hp full rate pump preferably a whisperflo. Add a 30" sand filter, and all 2" piping and you will be all right. Make sure that they have a individual pipe for the main drain and the skimmer. I would also suggest 4 returns on a pool that size. Just about every quality piece of equipment made these days has 2" or larger in and out.


My sizing is actually considered undersized as far as the piping goes for some builders, but anything bigger on a 1hp and the pump would more than likely cavitate and be a little bit louder than I would like. 80 gpm seems about right from a 1.0 hp pump it hits the pumps peak efficiency curve nicely.

I cannot say their system doesnt work, however it give you no room to expand, and is very inefficient. I thought the people I worked with up here were dinosaurs when it comes to pipe sizing, but 1 1/2" pipe on a 45k gallon pool, most pools this size from the early 70's have 2" pipe.


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RE: Pipe size for inground pool

Racket-

I really appreciate your help. Another question. The builder stated:

"all inlets and outlets in the pool wall and floor are factory cut for 1 " so an extra $600 will be added to the price to up size these openings."

Do the inlets and outlets on pool need to be enlarged to 2 inch or is it ok to use a reducer to fit the 1.5 opening on pool? Would the reducer defeat the purpose of having 2 inch pipe?

I really appreciate your help.


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RE: Pipe size for inground pool

What do you think of this for the pool plumbing versus there recommendation.

My Plumbing recommendations based on feedback
1. 2 drains (plumbed together with shutoff valve)
2. 4 returns (seperately plumbed with shutoff valves)
3. 2 skimmers (seperatley plumbed with shutoff valves)
4. 2 inch pipe for everything
5. s270t2(3.71) filter 2 inch
6. Hayward Super Pump II 1.5 HP 2 inch fitting
7. Hayward Heat Pump 1.5 fitting so have to use reducer to connect 2 inch pipe

* I guess based on my prior question. I will ask is it a viable option to use 1.5 pipe for return lines since the pool has 1.5 inlets and outlets or stick with 2 inch all the way around and have them use reducers? I will also assume the skimmers have 2 inch fittings?
===========================================================
The pool company's plumbing recommendations
1. 1 drain
2. 2 returns (sperately plumbed with shutdoff valves)
3. 2 skimmers (seperatley plumbed with shutoff valves)
4. 1.5 inch pipe for everything
5. s244(t3.14) filter 2 inch
6. Hayward Super Pump 1.5 HP 2 inch
7. Hayward Heat Pump 1.5 using 1.5 pipe


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RE: Pipe size for inground pool

Do the inlets and outlets on pool need to be enlarged to 2 inch or is it ok to use a reducer to fit the 1.5 opening on pool? Would the reducer defeat the purpose of having 2 inch pipe?

No, the purpose of having 2" pipe is to reduce the velocity which in turn ruduces the energy used to move the water.

If you have more than one inlet, which you should, then there will be multiple lines that split off the larger trunk line.

1. ok
2. you only need 1 return line, balancing can be done if desired with different sized eyeballs. To Plumb and valve everything would be very expensive with little result.
3. 2 skimmers can run off of 1 2" pipe, you can run them independently, but its not needed.
4. 2" pipe is good, if you have to reduce its ok to do it at the appliance, or pool.
5. I would use a 30" tank for a pool this big, you will exceed the max flow rate on a 24 and have far more frequent backwash intervals.
6. I don't like superpump's I'd Suggest Pentair, or Jandy pumps as they seem to be the best built and supported.
7. I don't trust hayward to make a heater let alone a heatpump. I would look into Raypak, Pentair, or aquacal offerings.

You will not get me or most people on this forum to approve hayward product, it is cheap macro builder equipment with horrible service and support. Even something as simple as a ball valve they seem to mess up. I am a Pentair backer but I also like Jandy, and Sta-rite's offerings.

I know talking to other people in your position that it can take an act of god to get people to derive from their standard equipment selections, but it's worth a shot because their warranty is more than likely one year, but I would imagine you are going to have to live with this for a very long time.


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RE: Pipe size for inground pool

Racket-

I really do appreciate all of your help. A couple of last questions in regards to your feedback.

2. you only need 1 return line, balancing can be done if desired with different sized eyeballs. To Plumb and valve everything would be very expensive with little result.

"So your point is to have 1 single line ran but have 4 different returns plumbed in the same pipe?"

3. 2 skimmers can run off of 1 2" pipe, you can run them independently, but its not needed.

"Will I not gain more pressure if I run these independently?"
4. 2" pipe is good, if you have to reduce its ok to do it at the appliance, or pool.
"As result, you are recommending to leave the 1.5 inlets/outlets on pool and save the $600 upcharge?"
The only reason I was thinking about plumbing returns and skimmers seperately is in the event of a pipe leak I could just shut off that line and not bust all the concrete out to fix it. Do you think it would make sense to do the follwoing for this pre-caution.

Put 4 skimmers in and have 2 on each independent line. Put 4 returns in and have 2 on each independent line.
In the event of a LEAK, I could shutdown the line for the skimmer or return with the LEAK and still have 2 skimmers or returns and not have to bust the concrete up. This is going over board but I would not ever want to bust it up with the price of concrete.


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RE: Pipe size for inground pool

Yes,

You may, but the suggested flow rate over the weir in the skimmer is about 1/2 a 2" pipe would handle.

4 skimmers is overkill. If you have a leak, the extra piping would give you more options. After all it is your money so if you feel it is worth it I couldn't say the extra piping is detrimental in any way.


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RE: Pipe size for inground pool

Guys-

Final decision. I've narrowed this down to two options and would like some feedback on what people think is the best.

Option 1

1. 4 returns plumbed on seperate lines with ball valves on each line
2. 2 skimmers plumbed on seperate lines with ball valves on each skimmer
3. 2 drains on the same line tee'ed with a ball valve
4. Hayward S370T2 filter
5. Hayward Northstar 1.5 HP pump
6. Everything is plumbed in 2 inch pipe

Option 2
Same as above except the underground pipes are 1.5 inch and all run into 2 inch manifold so all lines coming from 2 inch manifold go to 2 inch connectors on pump and filter.

I'm considering option 2 because one of the pool builders is concerned I will not have enough suction for pool clearn if I use 2 inch underground. Any suggestions.


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RE: Pipe size for inground pool

Did you guys give up with the feedback? I'd really like a last opinion before signing my contract and deciding on best way to plumb it.


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RE: Pipe size for inground pool

Loop the return line plumbing and lose the ball valves


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RE: Pipe size for inground pool

I had a pool installed with 1.5hp pump with 1.5" lines. Contractually, I was suppose to get 2HP pump with 2" lines. The pool is backfilled and now my question is can I use the 2hp pump and leave the 1.5" lines? It is a 40 thousand gallon pool with 7 returns and 2 wide mouth skimmer one main drain and 2 side wall drains. Do I need 2" lines with 2 hp pump?


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