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3" Pvc Piping W/ 1hp Pump ?


Agent86
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Greetings...

First off lemme say that is seemed easier building a custom house than it is meeting with all the pool builders....

Question...currently looking at the following configuration for our pool:

Approximately 25k gallon pool

38' x 18' free form kidney shaped variation

~108' perimeter

Most pool builders are quoting anything from 2", to 2.5" PVC piping with a 2.5HP pump...

One builder is using 3" piping (suction?) with no 90 degree elbows, at most 45 degree bends, all with a 1HP hayward pump....

Anyone shed any light on the advantages/disadvantages with the 3" vs 2"?

Thanks

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Greetings...

First off lemme say that is seemed easier building a custom house than it is meeting with all the pool builders....

Question...currently looking at the following configuration for our pool:

Approximately 25k gallon pool

38' x 18' free form kidney shaped variation

~108' perimeter

Most pool builders are quoting anything from 2", to 2.5" PVC piping with a 2.5HP pump...

One builder is using 3" piping (suction?) with no 90 degree elbows, at most 45 degree bends, all with a 1HP hayward pump....

Anyone shed any light on the advantages/disadvantages with the 3" vs 2"?

Thanks

I recently increased my pipes from 1.5 to 2" and e-mailed Hayward about pump size,here is the response.

When you are replacing your plumbing lines you do not need to

increase your pump size. You want to make sure your filter can

handle the flow rate of the pump.

Hayward Technical Services

One Hayward Industrial Drive

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My recommendation is to have 4 skimmers with each having its own 2-inch line going all of the way to the pump with a 1.5" or 2.0" Jandy Never-Lube valve for each line. A main drain is optional, but in my opinion, unnecessary, especially if you have an automatic cleaner.

You should have a 1.5 H.P pump. The 1.5 h.p pump should have a 2.0" intake. You should have 2 separate 2.0" return lines going from the output of the filter back to the pool and entering the pool as wall returns, not floor returns. The wall returns should have threaded fittings so that they can be plugged, if necessary.

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If you have long pipe runs and will need higher flow rates (say, for a solar system), then using 2.5" or 3" pipe will result in far lower resistance with greater efficiency and lower electricity cost. However, pumps are designed to have some "head" or resistance so the pump should be appropriately sized for the system. If I had to redo my pool plumbing, I would have had the PB use larger pipes than 2" to/from the solar and to the pool.

You might consider getting an IntelliFlo variable speed or variable flow pump. I cut my electricity costs in half when I went to the IntelliFlo from a 1 HP pump and a 3/4 HP booster pump (for a pressure-side pool cleaner). If I didn't have a solar system, I would have saved 80% on electricity. The power goes up a LOT faster than the flow rate and using larger pipes significantly reduces this.

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It all boils down to "turn over rate"...and efficiency. It's unlikely anyone on this board can do anything other than GUESS at what you need. Pipe size, length, number of turns, resistance of the filter, heater and anything else in the plumbing all effect the flow rate. The goal is to have the proper turn over rate (flow rate), with a pump that uses the least amount of electricity.

Yes, there are builders that simply make an educated guess, and frequently get close, though they risk over-sizing the pump, under-sizing the plumbing and costing YOU extra in electricity). Or perhaps they over due the pipe sizing and suction fitting, also costing you more than necessary. Then there are builders that actually sit down and do the calculations to get it perfect.

BTW, pumps push water. They're very inefficient at pulling water....hence larger diameter suction piping.

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It all boils down to "turn over rate"...and efficiency. It's unlikely anyone on this board can do anything other than GUESS at what you need. Pipe size, length, number of turns, resistance of the filter, heater and anything else in the plumbing all effect the flow rate. The goal is to have the proper turn over rate (flow rate), with a pump that uses the least amount of electricity.

Yes, there are builders that simply make an educated guess, and frequently get close, though they risk over-sizing the pump, under-sizing the plumbing and costing YOU extra in electricity). Or perhaps they over due the pipe sizing and suction fitting, also costing you more than necessary. Then there are builders that actually sit down and do the calculations to get it perfect.

BTW, pumps push water. They're very inefficient at pulling water....hence larger diameter suction piping.

Here's a pump sizing formula.

http://www.poolplaza.com/pool-pump-sizing-2.shtml

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That's a great site for determining the easy parts of what needs to be known, such as the minimum and maximum GPM rates. However, the dynamic head calculations are a function of details they don't describe such as pipe size and length. They talk about fittings, filter and other items, but these all have their own "Feet of Head" vs. "GPM" curves -- they aren't single numbers.

For example, for various fittings on pipe, there is this link to determine the equivalent feet of straight pipe (of various sizes). A straight pipe head loss table is here.

Finally, the site you linked to makes no mention of how much more expensive it is to have the same flow rate going through a higher feet-of-head resistance due to narrower pipe. It's true that if your flow rate is largely limited by certain sized fittings (such as returns), that having very large pipe will have diminishing returns. So 3" may be overkill in most situations. However, with long pipe runs in a pool with normal fittings, I can tell you from personal experience that 2.5" pipe would have saved me substantially in energy costs when I needed 48 GPM for my solar panels. To give you an idea of energy differences at different flow rates, the following are real measurements for my pump with the solar off (so shorter pipe length) using 2" pipe with runs of around 40-70 feet between pump and pool:

15 GPM (17.78 hours), 1185 RPM, 155 Watts ---> 2.76 KWh

18 GPM (14.81 hours), 1325 RPM, 195 Watts ---> 2.89 KWh

24 GPM (11.11 hours), 1460 RPM, 255 Watts ---> 2.83 KWh

26 GPM (10.26 hours), 1495 RPM, 275 Watts ---> 2.82 KWh (measured at different time so might be a little higher in reality)

30 GPM (8.89 hours), 1805 RPM, 420 Watts ---> 3.73 KWh

36 GPM (7.41 hours), 1975 RPM, 535 Watts ---> 3.96 KWh

40 GPM (6.67 hours), 2075 RPM, 615 Watts ---> 4.10 KWh

42 GPM (6.35 hours), 2160 RPM, 685 Watts ---> 4.35 KWh

48 GPM (5.56 hours), 2310 RPM, 835 Watts ---> 4.64 KWh

54 GPM (4.94 hours), 2490 RPM, 1030 W ---> 5.09 KWh

60 GPM (4.44 hours), 2710 RPM, 1305 W ---> 5.79 KWh

66 GPM (4.04 hours), 2900 RPM, 1590 W ---> 6.42 KWh

72 GPM (3.70 hours), 3080 RPM, 1895 W ---> 7.01 KWh

78 GPM (3.42 hours), 3360 RPM, 2495 W ---> 8.53 KWh

With the solar on where the pipe length adds over 500 feet to total (round-trip to/from solar) pipe length (solar headers are also 2"):

42 GPM (6.35 hours), 2750 RPM, 1180 Watts ---> 7.49 KWh

48 GPM (5.56 hours), 2980 RPM, 1500 Watts ---> 8.34 KWh

54 GPM (4.94 hours), 3315 RPM, 2050 Watts ---> 10.13 KWh

The times in parenthesis are for one turnover in my 16,000 gallon pool at the flow rates (GPM) indicated. So the KWh is the total electricity usage for one turnover. You can see how higher flow rates are much more expensive. Using 2.5" pipe instead of 2" pipe cuts down the head loss by a factor of 2.4 (so head loss for 2.5" pipe is 42% of the head loss of 2" pipe). Even if you kept the same flow rate, that means a reduction in electricity costs by roughly that same amount -- a factor of 2.4. This assumes that you have a variable speed/flow pump so that you can reduce the pump speed to achieve the same desired flow rate. If you have a fixed-speed pump of the same HP, then all that happens is that you get faster flow rates and not as much energy savings. It is the combination of larger pipes with a variable-speed pump (or lower HP fixed-size pump) that will give you the greatest savings in energy consumption.

Richard

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I always size pipe for velocity or feet per second (fps). I use max 5fps for suction and max 10fps for pressure side.

That will ensure that you are using the minimum pipe size needed to handle the maximum flow rate, but why don't you use an even larger pipe size to gain energy efficiency so you can use a lower HP pump or a lower speed with a variable speed pump?

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Another consideration is future problem solving.

In my recommendation, I noted (4) two-inch suctions and (2) 2-inch returns. The (4) 2-inch pipes are equivalent to (1) 4 inch pipe, and the two 2-inch pipes are equivalent to a 2.83 inch pipe. The big advantage of having multiple lines comes if you have a leak in the plumbing. If you have a leak, you can simply plug the affected line and continue filtering uninterrupted, and deal with the leak at your leisure.

Also, with four skimmers, you will get increased surface cleaning and less chance of your skimmer baskets becoming overloaded.

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Sorry I missed the multiple pipes in what you wrote. You're absolutely right and what I wrote with regard to larger pipes was in terms of long runs of a single pipe as often occurs with solar panels or with the main run to returns in the pool. For the suction line, there are often more than one -- one for the skimmer(s) and one for the floor drain(s). I've got to read these posts more carefully! :rolleyes:

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Thanks all for the wealth of information...

I should have mentioned in the beginning besides the approximately dimensions/capacity of the pool...it also has an ~20' infinity edge....

and besides the 1hp pump for the pool (3" suction line), the company is also using a dedicated 3hp pump for the catch basin...

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I also have a multi speed pump and I can really recommend it.

If larger diameter piping doesn't cost much you can save but make sure you get some sort of variable speed pump to realize the savings.

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Very important.

The catch basin will probably hold about 1,000 gallons of water. You have to treat it like a separate small pool or hot tub with its own pump and filter. Otherwise, the water in the catch basin will get green and dirty and the dirty, algae water will get pumped into your main pool every time you run the 3 hp pump.

I would recommend a 3/4 hp pump, a cartridge filter, (2) 12 x 12 inch main drains for suction, each with its own two inch line to the circulator and (2) two inch returns to the catch basin. You can't use skimmers in the catch basin because the water level changes by about 12 to 24 inches when the 3 hp pump is on.

I would use (3) 12 x 12 inch main drains for the suction of the 3 hp pump each with its own 3 inch line to the 3 hp pump and (2) three inch pipes to return the water to the pool.

You should also put an extra main drain in the basin with a two-inch line that goes into the suction of the primary circulator pump. Be sure to add a check valve in-line to prevent water flowing from the pool to the catch basin when the primary pool pump is shut off.

For your primary pool, you should include an extra two-inch pipe to be used to add a Polaris type pressure side cleaner later if you are not going to add one now. It can be used as a return in the meantime. Make sure that it has a 1.5 inch or 2.0 inch threaded adaptor at the point where it goes through the wall.

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Often builders will tie similar pipes together underground. They will often run all of the skimmer pipes to a single point underground, tie them together and then run a single line from there to the pump. Do not allow them to do this. Make sure that every skimmer line runs all of the way to the pump. Do the same thing with main drains etc.

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I always size pipe for velocity or feet per second (fps). I use max 5fps for suction and max 10fps for pressure side.

That will ensure that you are using the minimum pipe size needed to handle the maximum flow rate, but why don't you use an even larger pipe size to gain energy efficiency so you can use a lower HP pump or a lower speed with a variable speed pump?

If you run the calculation you will find the (minimum pipe size) larger and the efficiency more than you think.

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If you run the calculation you will find the (minimum pipe size) larger and the efficiency more than you think.

10 fps on the pressure side in 2" pipe is 105 GPM! You can't be serious about that. Yes, this is what the pipe can handle but 105 GPM through 2" pipe is a head loss of 14.7 feet (6.4 PSI) per 100 feet which is VERY high if you have long pipe runs. If I use 2.5" pipe, then that same 105 GPM has a velocity of 7 fps and a head loss of 6.2 feet (2.7 PSI) per 100 feet. If I use 3" pipe, then 105 GPM has a velocity of 4.6 fps and a head loss of 2.2 feet (1.0 PSI) per 100 feet. Obviously, if the maximum GPM one has is lower or their pipe runs are shorter, then 2" pipe can be fine, but I know in my own pool with 2" pipe on the pressure side that the very long pipe runs with even 48 GPM results in much higher energy costs (as I showed in my earlier post) and could have been reduced had larger 2.5" pipe been used.

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I am going to recommend a 2 hp variable speed pump for the main pool circulation and a 3/4 hp variable speed pump for the catch basin filtration. I am also going to recommend that you have (3) 2-inch pipes for returns for the pool circulation.

A few questions:

1) What will be the thickness of the concrete that will form the shell of your pool?

2) What will be the rated strength of the concrete?

3) What will be the diameter of the rebar that will be used?

My recommendation is to be sure that you go with higher than average specifications for all three of these things. Otherwise, you run the risk of structural cracks, which are a pain to have to deal with.

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Clarification: In my earlier post, I said that multiple smaller pipes were equivalent to a single larger pipe. Although they do have the same volume, the smaller pipes have more surface area in contact with the water.

Therefore, one larger pipe will have a slight advantage as far as overall efficiency. The big advantage in having the multiple pipes is the risk management benefit provided by the redundancy. I would estimate that at least 10-15 % of all pools end up with at least one underground plumbing leak at some time.

Having multiple lines also gives you the opportunity to add new equipment, or make other such changes at a later time, such as a Polaris pressure side cleaner etc.

Having an "over-plumbed" pool can also give you the opportunity to upgrade a pump at a later time if you want to, or need to.

I am also going to recommend that you include a 2-inch return line from the catch basin filtration to the main pool.

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As well as making sure that your plumbing is sized correctly, you also need to be sure that the electrical supply is sufficient.

Undersized or minimum sized wires will also cost you in efficiency. Like plumbing, over-sizing wiring costs a little more initially, but pays off in the long run. Whenever possible always go 230 volts.

Be sure to include extra electrical conduits from the power supply to the equipment area to allow for the addition of extra equipment at a later time.

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After further consideration, I am going to update some of my recommendations.

I am going to recommend against a main drain. It does not provide any significant benefit and it uses valuable suction that would be better used by a skimmer.

Main drains are mostly worthless. They are an unnecessary hazard. See these videos for the uselessness and danger of main drains.

(Drain Testing using Dye For Effect on Pool Circulation)

(Swimming Pool Drain Safety)

http://www.youtube.com/watch?v=C54nZlnRtw0 (Swimming Pool Suction Entrapment)

(Is Your Pool's Drain Safe)

(20/20: Pool Entrapment - Part 2)

http://www.fluent.com/news/pr/pr130.htm (Simulation of Water Circulation Improves Safety of Swimming Pools)

See this report for the scientific evidence that main drains do not improve circulation.

http://www.fluent.com/solutions/sports/CS1...ilogy-pools.pdf

To provide adequate circulation in this pool, I would have either

1) Four separate 2-inch PVC return lines that go all of the way from the equipment to the pool and then branch into a total of eight returns to enter the pool. OR

2) Three separate 2.5-inch return lines that go all of the way from the equipment to the pool and then branch into a total of eight returns to enter the pool. OR

3) Two separate 3.0-inch return lines that go all of the way from the equipment to the pool and then branch into a total of eight returns to enter the pool.

This will provide the necessary flow to all areas of concern. Furthermore, the use of an automatic cleaner will completely obviate any need for a main drain.

I recommend the Pentair IntelliFlo VS SVRS pool pump as shown here for your circulation if you go with a main drain. http://www.pentairpool.com/products/products3.php?id=76

It can deliver up to 140 GPM at the highest speed of 3450 rpm at 55 feet of head (24 psi.) as shown here:

http://www.pentairpool.com/pdfs/intelliflosvrsB.pdf

It comes with built-in Safety Vacuum Release System. It is rated up to 3.45 Horsepower. 230 volt. 16 amps at full load.

I recommend the Pentair IntelliFlo VF High Performance Pump for your circulation if you go without a main drain (The VF stands for Variable Flow vs. Variable Speed). It monitors the flow rate that you have programmed in and it keeps it at that number.

The variable speed has eight different speeds but does not actually monitor the flow rate. It seems that the VF does not come with a Safety Vacuum Release System option.

For your Infinity edge, I recommend the Pentair IntelliFlo VS SVRS pool pump as shown here: http://www.pentairpool.com/products/products3.php?id=76

It can deliver up to 140 GPM at the highest speed of 3450 rpm at 55 feet of head (24 psi.) as shown here:

http://www.pentairpool.com/pdfs/intelliflosvrsB.pdf

It comes with built-in Safety Vacuum Release System. It is rated up to 3.45 Horsepower. 230 volt. 16 amps at full load.

I recommend that the suction for the 3 H.P Infinity Edge pump be provided by four 12-inch x 12-inch main drains that are all connected by three inch pipe and then go to the pump through one 4-inch suction.

I recommend that the suction for the catch basin circulation/filtration be provided by three 12 x 12-inch main drains that are all tied together with 3-inch pipe and then go to the 3/4 H.P catch basin circulator pump suction by a 2.5 inch pipe. The catch basin suction should have a Safety Vacuum Release System (SVRS)

There are several concerns with the catch basin.

1) The main drains will provide the only suction to the 3/4 and the 3.0 HP pumps. This can be very dangerous.

Although the catch basin is not designed or intended for people to get in, it is what is known as an "Attractive Nuisance". This means that children will be interested in going into the catch basin, even though they shouldn't.

Therefore, the catch basin must be designed to either keep kids out, or to be safe if they get in.

The Infinity Edge will act as a giant skimmer when it is on. This can quickly clog the main drains with debris such as leaves etc. The main drains should be routinely checked to insure that the drain covers are secure, intact and not clogged with debris.

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  • 4 weeks later...

Simple answer: for circulation system, big pipes small pump. Most efficient. Many builders like to sell horsepower not efficiency. After all, would you want a 25 hp engine in your 'vette or 250 hp? Don't apply that thinking to pools, think opposite of cars.

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  • 11 years later...

Found an old post with a lot of good information.   

I am in the process of putting an inground pool in.   The shape is free-form but the rough dimensions are 25x42.  I plan on two skimmers and was thinking of using a deep end drain before reading this.    I am now attempting to plan my plumbing and trying to get a very efficient system.    I can use any size pipe and number of feeds and returns at this point of the build.   According to some calculators, it seems I will be near 40,000 gallons.  In order to get 3 turn overs each day I would need to use 3 in pipe.    Do I need to use 3 inch fittings in the pool? Do I need a pump and filter with 3 inch fittings?  Or can I simply reduce to 2 inches right before the valves and into a single 2 inch pipe into the pump? 

Hoping all the smart guys are still members of this site.

 

Thanks!

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