I love this site! It has been a big help as we plan for our new pool. One question I have had is about pipe size. I have noticed a number of posts that recommend 2 or 2 1/2 inch pipes. My PB uses 1 1/2 inch pipes. When I asked about it he sailed that the fittings are standard at 1 1/2 inches for most pools. His explanation was that larger pipe size won't matter if the joints and fittings are smaller. He offered to use 2 inch if I wanted but thought it was unnecessary and won't impact water flow. Could someone help me understand the importance of pipe size?
PB says bigger than 1 1/2 inch pipes unnecessary
- Thread starter Pp09722
- Start date
The PB is wrong.
There are people on here much smarter than I, but here goes:
The flow resistance in any pipe setup is measured in feet of head. All pipe and fittings have resistance and contribute to this number. Larger pipe/fittings/etc. have less resistance than smaller pipe for the same distance. So, if you run 2" pipe for the entire run except for the ends (1.5"), your total head will be lower than if you used 1.5" pipe throughout.
Low head is good. Less resistance = greater flow rate = less electricity used to circulate the water. Generally pipe size is more important on the suction side, so if I were building a pool I would get at least 2.5" on the suction side and 2" on the return side. I don't know at what point the extra cost of large pipe negates the energy savings.
What size/model pump are you having installed? Many builders install pumps that are way too large and waste electricity. Are you going to have water features (fountains, waterfalls, etc)?
There are people on here much smarter than I, but here goes:
The flow resistance in any pipe setup is measured in feet of head. All pipe and fittings have resistance and contribute to this number. Larger pipe/fittings/etc. have less resistance than smaller pipe for the same distance. So, if you run 2" pipe for the entire run except for the ends (1.5"), your total head will be lower than if you used 1.5" pipe throughout.
Low head is good. Less resistance = greater flow rate = less electricity used to circulate the water. Generally pipe size is more important on the suction side, so if I were building a pool I would get at least 2.5" on the suction side and 2" on the return side. I don't know at what point the extra cost of large pipe negates the energy savings.
What size/model pump are you having installed? Many builders install pumps that are way too large and waste electricity. Are you going to have water features (fountains, waterfalls, etc)?
The larger the pipes are, the less resistance to flow there is. Smaller diameter pipes mean that the pump has to work harder to move the water.
Try this, get yourself a straw and a paper towel roll. Put the straw in your mouth and blow all the air you have in your lungs out through the straw. Kinda tough isn't it? Now, do the same thing with the paper towel roll. See what I mean?
My pool is all 2" pipe. I have seen 1.5" but it seems to be rare on IG pools. I have seen 1.5" more on AG pools.
Try this, get yourself a straw and a paper towel roll. Put the straw in your mouth and blow all the air you have in your lungs out through the straw. Kinda tough isn't it? Now, do the same thing with the paper towel roll. See what I mean?
My pool is all 2" pipe. I have seen 1.5" but it seems to be rare on IG pools. I have seen 1.5" more on AG pools.
- May 3, 2007
- 18,076
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
You can design pool plumbing to be efficient with 1 1/2" piping but you need to have many more parallel runs. If you use 1 1/2" line for two skimmers and main drain with runs all the way from pool to pad, those three lines are the equivalent to about a single 2.3" line. Same for the returns so it depends on how he plans to do the design.
But personally, I would use parallel runs with 2" pipes so the equivlent size is 3", assuming 3 suction lines. On the return side, I would use 2" runs for every pair of returns. So with 4 returns and 2 runs, the equivalent size would be 2.6". Even this design might be somewhat overkill depending on the pump chosen.
Also, his comment regarding standard fittings doesn't really make a lot sense since you can change pipe size at any point along the run. Most pools will use larger pipe for the longer runs and then reduce the size near the returns for the eyeballs. This is a faily easy and cost effective way to do things.
But personally, I would use parallel runs with 2" pipes so the equivlent size is 3", assuming 3 suction lines. On the return side, I would use 2" runs for every pair of returns. So with 4 returns and 2 runs, the equivalent size would be 2.6". Even this design might be somewhat overkill depending on the pump chosen.
Also, his comment regarding standard fittings doesn't really make a lot sense since you can change pipe size at any point along the run. Most pools will use larger pipe for the longer runs and then reduce the size near the returns for the eyeballs. This is a faily easy and cost effective way to do things.
Thanks, all! I am brandy new to all of this and am rushing to educate myself. I want ask the right questions and get the right set up, but I honestly don't have the time or inclination (or the knowhow) to get too involved in managing my PB's plans.
With that said... I've been told that a 1 hp pump is recommended for his set up. I don't have any plans for waterfalls or other water features, but I will have a water slide. I think we will have two skimmers and three returns (though I may ask for one more at the stairs). I am inclined to go with 2 inch pipe on the suction side and 1.5 inch on the return side depending on the way he plans to set up the pool.
With that said... I've been told that a 1 hp pump is recommended for his set up. I don't have any plans for waterfalls or other water features, but I will have a water slide. I think we will have two skimmers and three returns (though I may ask for one more at the stairs). I am inclined to go with 2 inch pipe on the suction side and 1.5 inch on the return side depending on the way he plans to set up the pool.
I think that a return at the steps, as you mentioned that you are inclined to request, is a very good idea.
If the PB plans to have floor drains and skimmers in the pool, then a common setup is to have separate piping for the skimmers vs. the floor drains going all the way to the equipment pad so that you can turn on/off these two sources separately. If that is the case, then 1.5" piping for each is reasonable and equivalent to one 2" pipe. For the returns, however, it is more common to use 2" pipe from the equipment pad to near the pool and then to split to individual 1.5" pipes for each return (assuming there is more than one). If the equipment is close to the pool, then I can see splitting to individual 1.5" pipes for each return close to the equipment pad which may be what he is doing.
If it were my pool and if electricity were expensive, I would go with the largest reasonably priced pipe and with a variable speed/flow pump. It's easy to add resistance if needed, but virtually impossible to lower resistance without re-piping.
If it were my pool and if electricity were expensive, I would go with the largest reasonably priced pipe and with a variable speed/flow pump. It's easy to add resistance if needed, but virtually impossible to lower resistance without re-piping.
Since this is your pool, shouldn't you get what you want?! Once the job is complete and the PB has his money, you'll be the one fighting his "standard" 1 1/2" plumbing and he'll be long gone 
Here's another question that makes my blood boil: why does he want to run 2" suction and then skinny the return water down to 1 1/2"? Why not come and go with the same size (and have him loop the return line at the pool also!)?
Honestly, I don't even like 2" plumbing. I use 2 1/2" minimum (the cost is not much more; maybe you could offer to pay the difference in his "standard" weenie sized pipe to the bigger pipe!), and I always stay the same diameter coming and going. Guess what? My pools run very efficiently, the pumps are extremely quiet, and the water flows easily. Isn't that what it is supposed to do??
Please don't let him use the 1 1/2" pipe. You'll be much happier with larger diameter pipe, even if it costs a few bucks more up front. The labor should be the same to install the larger pipe, so it really should just be the cost difference in the material. Hold your ground and explain to him your reasoning, and remember, it's your pool and your paying the bills!
Here's another question that makes my blood boil: why does he want to run 2" suction and then skinny the return water down to 1 1/2"? Why not come and go with the same size (and have him loop the return line at the pool also!)?
Honestly, I don't even like 2" plumbing. I use 2 1/2" minimum (the cost is not much more; maybe you could offer to pay the difference in his "standard" weenie sized pipe to the bigger pipe!), and I always stay the same diameter coming and going. Guess what? My pools run very efficiently, the pumps are extremely quiet, and the water flows easily. Isn't that what it is supposed to do??
Please don't let him use the 1 1/2" pipe. You'll be much happier with larger diameter pipe, even if it costs a few bucks more up front. The labor should be the same to install the larger pipe, so it really should just be the cost difference in the material. Hold your ground and explain to him your reasoning, and remember, it's your pool and your paying the bills!
simicrintz said:
I'm curious, how many options are there in filters, MPV's and pumps sized appropriately to the OP's 25K gallons that accept 2 1/2" plumbing? Or do you have to reduce down at the pad?
Durk said:
Yes, you do have to reduce down for the equipment, but it is kept to a minimum. I try to get back up to full dimension as quickly as possible after that. You also have to bush down on the return fittings (I go down to 1 1/2" pipe on my return wall penetrations, which is one reason that I like to loop the return system also), and skimmers come out at 1 1/2" so I have to bush up for that/those runs.
Here's the way I look at it; if I can give a better, quieter, more efficient pool for the cost of larger pipe, why wouldn't I? If I can push water slower, and at greater volume, creating a system that cleans better (slower water filters more efficiently) and heats better, why would I argue with a customer? Don't I want to build the best that I can, and have as many happy customers singing my praises as possible? What value comes in trying to save a few cents and alienating a huge referral source?
This is all about flow rates. Water flows better in bigger pipes. Moving water cleans and heats better than restricted water. Let it flow!
mas985 said:
I think the PB is imagining in his mind what I am... and that is if the returns/eyeballs are 1.5" then how can more water come out of 1.5" at a time if the pipes are bigger. I'm not arguing against this as I have NO experience. That's why I'm reading this thread to get educated.
I'm thinking about a cake icing bag with a certain size tip on it. You can put a tiny bag on the end of it to hold a few ounces of icing or put a 20 gallon trash bag full of icing on it. When you squeeze it with the same pressure no more icing will come out at a time with the 20 gallon bag than the tiny one. So the flow rate is the same. That's probably a horrible example but that's what first popped in my mind. I think I want some cake.
So I'm trying to wrap my head around how bigger pipe can have more flow when it still gets restricted back down to 1.5" at the end. I can see how resistance will be less but don't see how flow rate changes. Well, I KIND OF can see how resistance will be less. I'm still stuck on the eyeball return being 1.5" and don't see how it can come out faster or slower just because bigger pipe is 'holding' more water. The motor on the pump is still spinning the same speed and moving the same amount of water through the PUMP.
I'm just trying to put myself in his shoes... but he should know better anyway since he's in the business and I'm not
Again I totally believe that if the experts/knowledgeable ones here say bigger is better (no jokes please) I'll agree. I'm just trying to get the concept down in my head.
I have a headache thinking about it
All pipe and fittings contribute to the total head loss in the system, which is nothing more than the sum of all its parts (all the straight pipe, elbows, valves, etc in your system). Here is a chart showing the head loss (expressed in feet of straight pipe equivalent) for various pipe sizes and fitting types (does not include eyeballs, but you get the idea).
Think of the 1.5" return eyeball just as another fitting (which is exactly what it is) in the plumbing. It adds some fixed amount to the head loss, but it still contributes a relatively small part of the total head loss of the system. Using larger pipe will get you a smaller total head loss , which is the ultimate goal. Seems a bit illogical at first, but people smarter than me (mas985) say it's true!
Have you read mas's sticky, Hydraulics 101 - Have you lost your head?
Think of the 1.5" return eyeball just as another fitting (which is exactly what it is) in the plumbing. It adds some fixed amount to the head loss, but it still contributes a relatively small part of the total head loss of the system. Using larger pipe will get you a smaller total head loss , which is the ultimate goal. Seems a bit illogical at first, but people smarter than me (mas985) say it's true!
Have you read mas's sticky, Hydraulics 101 - Have you lost your head?
This is a fantastic post everyone should read before believing any PB b.s. I learned alot from it after hearing about Variable speed pumps, Hydrolics explains the WHY of how the savings are achieved. 2 things you want for the lowest electric bill.Melt In The Sun said:
1. A pump just big enough to turn your pool once every 6-8 hours and the timer set to turn it just once
2. The largest suction and retun pipe you can afford. (this lowers "total dynamic head") which is the resistance your pump has to overcome to get the flow in GPH to the pool you need.
Bigger pipes are easier to push through, keeping the pump and everything elese the same for comparision, just like the straw example above. Let me give a example. My builder ran 2 2" suction lines, one for the skimmer, and one for the main drain, He ran one 1 1/2" line for 5 inch and a half eyeball returns. The pad is 5 feet above the pool and around the corner 60 plus feet
my DE filter clean reads 16 psi running on my 2.2HP(real HP) Pentair pump. IF I changed the pipe (unrealistic now being IG) or the builder wasn't soo cheap He would have run larger suction and return and maybe matched them. I would get lower HEAD :-D my pump would become more effecient and I could look at the pump curve and instead of 49 feet of head alowing 90 GPM flow I could easly be at 130 GPM 
Then I can simple divide the pool gallons by 130 to get how many mins to run the timer then divide that by 60 to get the number of hours to set the timmer to. Now instead of 3.7 hours a day to turn the pool once I can set the timer 2.5 hours 
Thats a 33% reduction in time which Directly translates to a 33% lower electric bill!So right now I pay 0.10/Kwatt hour and the pump runs 111 hrs/month In this example at 22amps@240v(11amps per phase)
so she sucks 2,640 watts, think of that as just over 26 100 watt lamps turned on in your house. That means this pump consumes 2.64 Kwatts/hr or 26 cents
So 3.7 hours at 26 cents/hr per day times 30 days =$28.86 per month
BUT run bigger pipe ONCE and let's calculate the savings
2.5 hours at 26 cents/hr per day times 30 days =$19.50 per month :-D
that saves over $110 EVERY year you run your pool, assuming you run year round. And If you run the pump longer the $$ savings are more!
Conclusion: Bigger pipe is just like insulation in your house, If you buy now up front you will save Money and be "green"
I think the 2 suctions (main drain and skimmer) should be min. 2 1/2 inch and the return 2 or 2 1/2" min. for any pool around 20000 or less. I think mine are skimpy and thats how builders make more money off you and compeat with others.
If you can affor bigger like all 2 1/2 or multiple 2 1/2 DO it!
Look at it like this, In the above example we saved 33% on the electric bill, Would going one size up on all the pipes from what the pool builder spec'ed out going to cost you more than an extra 33% just for the pipe/fittings cost pf the bill?
Maybe close but probally not so GO BIG there is only One time to do it right and thats now
Pp09722 said:
I hope this is a newbie sales guy(still no excuse) and not the owner or the pool designer because thats completely IGNORANT! Big Companys like Hayward, Jandy, and Pentair pay reps good money to train their dealers for FREE to make them more knowledgeable. Pump flow curves and hydrolics are covered and IT MAKES A DIFFERENCE! the pipe size and the number of fittings and how many degrees you turn the water overall impacts the efficiency of the system.
If he can't read the entire Hydrolics 101 thread and explain it to a client I would RUN!!!
This is the same BS I delt with in retail, salespeople telling customers their unfounded opinions as fact with no prior experience or responsibilty, Just make a sale baby!
I'm going to just say this; your pool builder.......Shifty Used Car Salesman.
The pool builder does have a point about the 1.5 " eyeball connecting to a 2" pipe, that is if all he ever use is 1.5 " eyeball. But whoever is going to do your plaster or pebble tec at the finishing stage, they should have different size eyeball for your pipe. My 2 cents.
i didnt read all of the replys in this forum but i would like to say this.
I service many pools in my area. Some have 1.5inch plumbing and some have 2inch.
i see no difference in how clean the pools are, how much they are spending on electric, and pretty much anything thats important to a homeowner.. does 2inch move more water? i would think so if its plumbed correctly. But almost every pump and filter combo comes standard for 1.5inch plumbing so there is nothing wrong with using 1.5"
The pools that were built in the 70's ( while i wasnt even a thought in my parents head lol) were built using 1.5in black poly pipe. There was usually only one skimmer and one return nowhere near that skimmer. The pools stayed clear.....
i think people get too worried about these sort of things when really its not a huge deal. Same with water chemistry. As long as your in rage, relax and enjoy the pool... thats why you had it built!
I service many pools in my area. Some have 1.5inch plumbing and some have 2inch.
i see no difference in how clean the pools are, how much they are spending on electric, and pretty much anything thats important to a homeowner.. does 2inch move more water? i would think so if its plumbed correctly. But almost every pump and filter combo comes standard for 1.5inch plumbing so there is nothing wrong with using 1.5"
The pools that were built in the 70's ( while i wasnt even a thought in my parents head lol) were built using 1.5in black poly pipe. There was usually only one skimmer and one return nowhere near that skimmer. The pools stayed clear.....
i think people get too worried about these sort of things when really its not a huge deal. Same with water chemistry. As long as your in rage, relax and enjoy the pool... thats why you had it built!
Matt-
Back in the 70's I was driving a Datsun pickup truck with no A/C or air bags, I had to pull over and fish change out from under the seat to find a pay phone to make my calls, and had to heat my dinner in the stove since there were no microwave ovens! Do I want to go back to that time again? No way!
Here's my point; those pools plumbed in the 70's (and lots of them still today) were plumbed poorly. Times have changed, we've gotten smarter. We better understand flow rates, looped systems, multiple return lines and multi speed pumps, to name a few. Don't be like every other pool guy out there and believe what someone told you, please! Take the time to learn why bigger pipe works better and how it does impact the pools ability to work easier. Here is a perfect chance to have a pool built like it should be built, not like a 70's pool (which this builder seems to be stuck in!).
Now that you have me thinking about the 70's, I'm remembering how much hair I had back then...... Ah, the good old days
Back in the 70's I was driving a Datsun pickup truck with no A/C or air bags, I had to pull over and fish change out from under the seat to find a pay phone to make my calls, and had to heat my dinner in the stove since there were no microwave ovens! Do I want to go back to that time again? No way!
Here's my point; those pools plumbed in the 70's (and lots of them still today) were plumbed poorly. Times have changed, we've gotten smarter. We better understand flow rates, looped systems, multiple return lines and multi speed pumps, to name a few. Don't be like every other pool guy out there and believe what someone told you, please! Take the time to learn why bigger pipe works better and how it does impact the pools ability to work easier. Here is a perfect chance to have a pool built like it should be built, not like a 70's pool (which this builder seems to be stuck in!).
Now that you have me thinking about the 70's, I'm remembering how much hair I had back then...... Ah, the good old days