Pipe size

[dykes26]

My PB is putting 2.5 inch intake (MAX GPM of 120) and 2 inch returns (Max GPM of 75). My question- 2 inch pipes have a max GPM of 75 right? If my DE filter needs to run at 90 GPM will there be too much stress on the smaller sized return lines? It seems like every pool build I have seen has smaller return lines than intakes. Do I need to bulk the return lines up?

 

[Guest]

I never understand why the PB'ers use big pipe coming in and restrict the water going back Makes absolutely no sense!

I would nicely ask him to use 2 1/2" going back as well, and have him loop the return system also. That way all of the returns will have the same amount of pressure, instead of the closest one getting the majority of the flow (path of least resistance) and the others getting the remainder. He can bush down the wall penetrations to 1 1/2" for eyeball fittings when he comes back to the pool.

2 1/2" pipe is not that much more than 2", and labor is the same. I see no reason why he would not accommodate you. In addition, your pump will work more efficiently and will run much quieter.

Bruce

 

[dykes26]

Thank you! I will do that.

 

[mas985]

My PB is putting 2.5 inch intake (MAX GPM of 120) and 2 inch returns (Max GPM of 75). My question- 2 inch pipes have a max GPM of 75 right? If my DE filter needs to run at 90 GPM will there be too much stress on the smaller sized return lines? It seems like every pool build I have seen has smaller return lines than intakes. Do I need to bulk the return lines up?

The flow rate specfication placed upon pipes are primarily to prevent failure in the pipe due to water hammer. However, this is not an absolute limit which prevents water from flowing faster. It can and it will. These limits are more like guidelines so the appropriate sized pump is used for the plumbing. But since you have an Intelliflo and from what I can tell, no need for high flow rates, I don't think it is going to matter much so you can pretty much ignore it.

Also, while larger pipe is always better than smaller pipe, sometimes it won't make that much of a difference. Especially at lower flow rates. But there are a few things that I would recommend. First, make sure the builder uses a full pipe run, pool to pad, for each skimmer and main drain pair. 2.5" pipe is fine for that. On the return, I would again use a full run for each pair of returns. But depending on the number of returns you have and the number of runs you have, you may be able to get away with 2" pipe without much of a change in head loss. With that size pool, I would go with 2 - 2" pipe runs (equivalent to a single 2.5" run) with a total of 4 returns unless you are looking for some water features for a bench and/or steps. Each pipe can be brought to the center of the two returns and split equally so the pressure and flow is identical to each return. This eliminates the need for loops and in my opinion works much better at equalizing flow rates.

 

[mas985]

I never understand why the PB'ers use big pipe coming in and restrict the water going back Makes absolutely no sense!

From an efficiency point of view I agree. However, pumps will usually run with much less noise if the return head loss is higher than the suction head loss. I have found that a 4:1 ratio is best but I would not sacrifice energy efficiency to get there. Usually going with a size larger on the suction is enough to keep the pump happy and the noise down. This is why I start with the return side plumbing to get to the correct pipe size for energy efficiency and then go with one size larger on the suction.

I believe that most PBs have found over time that when they use smaller pipe for the return, the pumps run quieter. This also prevents the suction side from sucking in air to the pump basket. But again, just because 2" pipe is used does not mean that the energy efficiency will be poor. If there are multiple runs, the head loss will be the same or lower than a single bigger pipe.

 

[Guest]

I never understand why the PB'ers use big pipe coming in and restrict the water going back Makes absolutely no sense!

From an efficiency point of view I agree. However, pumps will usually run with much less noise if the return head loss is higher than the suction head loss. I have found that a 4:1 ratio is best but I would not sacrifice energy efficiency to get there. Usually going with a size larger on the suction is enough to keep the pump happy and the noise down. This is why I start with the return side plumbing to get to the correct pipe size for energy efficiency and then go with one size larger on the suction.

I believe that most PBs have found over time that when they use smaller pipe for the return, the pumps run quieter. This also prevents the suction side from sucking in air to the pump basket. But again, just because 2" pipe is used does not mean that the energy efficiency will be poor. If there are multiple runs, the head loss will be the same or lower than a single bigger pipe.

I always run the same size plumbing coming and going (I used to do it the "old way" with one size bigger suction than return, but haven't done that for quite a while now. I have noticed (using a Fluke meter) a marked and drastic decline in amperage draw by letting the pump work more efficiently. Seems the pumps I use (Pentair and Hybrid) like to move water at low speeds, and I can keep the pump pot full in all cases with this pipe sizing (I'm not really that smart, I just listen! One of my buddies is a Genesis 3 guy, and I get alot of info from him!). Currently I am running a pool/spa combo, with solar and a waterfall on one pump, at 1,700 rpm. Drawing about 1.2 amps and keeping everything clean! 2 1/2" plumbing throughout. I do cam the solar bypass to slow the water to the panels, which does help a little with head pressure. I'm running about 8 psi on a dirty cartridge filter as well

Just another way of moving water! I like to push it slow and easy. Just get "upset" when a builder tries to save a buck and make a pool run way less efficient than it could. I would agree that the 2 1/2" coming and 2" going is miles better than what we normally see, and will be fine in shorter run (50' or so) applications!

I don't know it all (don't tell my wife I said that!), and that is why I'm on here; I'm always open to learning a better way

Bruce

 

[dykes26]

Thanks! I just checked my contract and will have 4 returns.

My worry is that the DE filter reccomends a flow of 90 GPM for best results- a 2.5 inch pipe should be fine, but the return pipes are designed for a maximum of 75 GPM

With four returns I should be fine right?

My VS will need to run the filter, suction side cleaner, 8 jet spa and get the water to the solar. I have 3 sheer decents, but will have a seperate 1 HP whisperflo for those.

Also, if the DE filter reccomends a 90 GPM flow rate wont I still have to run the VS about 1.5 HP- Id love to run the water slower longer to filter more and save energy.

This is a real education. Thanks in advance.

 

[Guest]

Any reason you are not using the Pentair Clean and Clear Plus cartridge filter? I like the 420 square foot one. Holds way more dirt that the DE and never needs backwashing! May be just a preference (I hate DE filters!), but I have to ask!

Bruce

 

[Guest]

Couple more questions

Why such a big pump for the Sheer D's? They use about 1 gpm per inch to flow, and unless you are running huge ones you should be able to downsize that pump.

How come you are not running a dedicated jet pump? That way you could use the VS for circulation (and not draw cold air while you are trying to heat the spa) and just hit the jet pump when you want jets. Sometimes it is nice to have warm, filtering water without the jets (like when you are enjoying a glass of wine and some nice conversation )

Sorry for all the questions! I just like to see what the thought process is sometimes!

Bruce

 

[mas985]

Thanks! I just checked my contract and will have 4 returns.

My worry is that the DE filter reccomends a flow of 90 GPM for best results- a 2.5 inch pipe should be fine, but the return pipes are designed for a maximum of 75 GPM

With four returns I should be fine right?

My VS will need to run the filter, suction side cleaner, 8 jet spa and get the water to the solar. I have 3 sheer decents, but will have a seperate 1 HP whisperflo for those.

Also, if the DE filter reccomends a 90 GPM flow rate wont I still have to run the VS about 1.5 HP- Id love to run the water slower longer to filter more and save energy.

This is a real education. Thanks in advance.

The DE flow rate spec is for a MAXIMUM flow rate. Flow rates less than that actually work better for filtration so you are fine with low flow rates. In fact, the lower the better for pump energy consumption. The Intelliflo has the best efficiency at around 1000 RPM so that should be your normal operating point. This is probably close to 30 GPM but again that depends on the head loss. If you are using your solar, you will probably be operating at somewhere around 40 GPM so this shouldn't be a problem at all.

Also, if you go with 2 - 2" return lines as I suggested, then really, you are talking about 75 GPM each or a 150 GPM total. But that is only if you want run the Intelliflo at that flow rate. But you really shouldn't need to.

But maybe you missed my other comment about those pipe flow rate maximums. You can go well above those limits without any negative affects other than high head loss. In order to cause a problem, you would need to shut the flow off instaneously to get enough pressure to bust the pipe. It is virtually impossible to do so don't put too much emphasis on those limits. They really aren't all that practical for pool plumbing. Except for the filter, there you could damage the grids so you should never exceed the maximum but you can always go lower. I wrote up and section in the Hydraulics 101 link in my signature if you are interested reading more about it.

 

[mas985]

Couple more questions

Why such a big pump for the Sheer D's? They use about 1 gpm per inch to flow, and unless you are running huge ones you should be able to downsize that pump.

How come you are not running a dedicated jet pump? That way you could use the VS for circulation (and not draw cold air while you are trying to heat the spa) and just hit the jet pump when you want jets. Sometimes it is nice to have warm, filtering water without the jets (like when you are enjoying a glass of wine and some nice conversation )

Sorry for all the questions! I just like to see what the thought process is sometimes!

Bruce

I agree, I think jets are probably better served on a separate large pump (2.5 HP) and larger pipes. That way to you can heat a spa then go back to pool filtering if wanted. With 8 jets, you might consider 3" pipe suction pipe and for the return a single run of 3" or two runs of 2.5". Also, do you know the flow rate requirement of the jets? Some required up to 25 GPM per jet.

Also, what size pipe is the PB planning to use for the sheer decents? Those are usually single lines and for that I would go with larger pipe as well so you can drop the size of pump. If you don't have much linear length for the decents, those could be serviced off the Intelliflo but then you would need the extra valves to control the flow.

 

[Guest]

Couple more questions

Why such a big pump for the Sheer D's? They use about 1 gpm per inch to flow, and unless you are running huge ones you should be able to downsize that pump.

How come you are not running a dedicated jet pump? That way you could use the VS for circulation (and not draw cold air while you are trying to heat the spa) and just hit the jet pump when you want jets. Sometimes it is nice to have warm, filtering water without the jets (like when you are enjoying a glass of wine and some nice conversation )

Sorry for all the questions! I just like to see what the thought process is sometimes!

Bruce

Also, what size pipe is the PB planning to use for the sheer decents? Those are usually single lines and for that I would go with larger pipe as well so you can drop the size of pump. If you don't have much linear length for the decents, those could be serviced off the Intelliflo but then you would need the extra valves to control the flow.

Not a bad idea to put a ball valve behind (in line) the Sheer D's either (behind each one). That way you can control the weirs independently. I also like to loop the Sheer D lines and equalize them as well. Nice to have even pressure that you can adjust as you desire.

Bruce

 

[dykes26]

There was not a process in this one. I just went with the PB's suggestions (before I found this site)

I will have 3 18 inch decents on 18 inch raised bond beam. What size pump would you use? Should I request a change order to a dedicated jet pump and switch the decents to to the VS?

Also should I requet 3 inch for the spa?

I love this site you guys are very helpful

 

[Guest]

There was not a process in this one. I just went with the PB's suggestions (before I found this site)

I will have 3 18 inch decents on 18 inch raised bond beam. What size pump would you use? Should I request a change order to a dedicated jet pump and switch the decents to to the VS?

Also should I requet 3 inch for the spa?

I love this site you guys are very helpful

Well, since 3 times 18 is 54, I would get a pump that pushes somewhere in the neighborhood of 60 gpm for the Sheer D's. A little more won't hurt, but I wouldn't go too much more or they will shoot all the way to the other side of the pool A 3/4 HP pump should be fine (the PB could also bypass some of the water to the pool if he had to for some reason).

I would leave the Sheer D's on a dedicated pump so that you can use them while you are in spa mode. If you try to use the circ pump to run the weirs then you will be unable to run them when the circ pump is circulating the spa water. The goal is to be able to run any configuration of water at any time, which will require 3 pumps (circ pump, jet pump and water feature pump) to allow your pool to run in any configuration.

How far is your equipment run from the pool? If the pool run is on 2 1/2" and is close to length as the spa then stay the same (for the circ pump). I would run the jet pump line (coming and going) in 3 inch, since the goal is to push water quickly (remember, it is not going through the filter or heater. It is just a straight run back to the jets). The water feature pump could easily be run in 2 inch as you will be running that seldom, will be a smaller pump, and will also have little or no resistance returning the water.

Bruce

 

[tmoss]

I run my 4 foot descent and a couple of 1" spouts with my VF and automated valves. That way I can tailor the flowrate and subsequent noise levels. I also have ball valves on each one to further customize the effect. I don't have a spa so I only have the VF for everything. I'd go with the biggest filter possible to minimize cleanings or backwashes, especially if running a suction cleaner. I have a 2" loop for my 6 returns and run 25 gpm @ 0-1# psi on a clean DE 100 filter. The water feature runs 35 or 45 gpm depending on how much noise I want to hear! And remember, your PB won't be paying your electric bill.

 

[mas985]

There was not a process in this one. I just went with the PB's suggestions (before I found this site)

I will have 3 18 inch decents on 18 inch raised bond beam. What size pump would you use? Should I request a change order to a dedicated jet pump and switch the decents to to the VS?

Also should I requet 3 inch for the spa?

I love this site you guys are very helpful

For the decents, again I prefer separate feed lines with control valves at the pump to control the flow to each decent. But since you only need about 20 GPM per decent, you can use 1 1/2" line. The three 1 1/2" lines will be equivalent to a single 2 1/2" line but you will have much better control over the flow rate of each.

You may be able to use the Intelliflo for the decents although it will need to run at fairly high flow rates to supply the decents and still have good skimming action for the pool. Just realize that there isn't much point in having an Intelliflo if you will be running at high RPM most of the time for the decents. However, if you use the decents only occasionally, then it is still probably worth having. Even if you have a separate pump for the decents, you will still have extra cost when running them but that is the price you pay for water features.

As for the spa, first find out what the flow rate requirements are for each jet so that we can determine how much the pump will need to produce. Also, how long will the run be from the pad to the pool? Depending on these requirements, it will determine the plumbing design as well as the type of pump(s) used. The spa plumbing is critical in that you want to make sure you have enough flow rate to get the effect you are looking for from the jets. Weak jets are no fun and very difficult and costly to fix. So this one you need to make sure you get right.

 

[dykes26]

Wow lots to think about-

My decents will run only now and then,

Ill see if he can run each decent with a seperate 1.5 line and have ball valves at the end of each one.

Cant the VS run the spa at 3 HP?- I know that the VS can be costly at higher rates but will run at short spurts.

My VS will be used mainly for filtering at low rate and the suction side cleaner.

What is the smallest sized pump I could use to push the three decents- with about a 15 foot run to the pool and a total run of about 30, 40 and 50 feet to each decent?

 

[mas985]

Since you haven't told me yet what kind of jets you are using, most use 15 GPM so that is 120 GPM total. An Intelliflo can deliver 120 GPM at 67' of head so it is possible but I wouldn't count on it. Even if you had 3" suction lines and return lines, head loss @ 120 GPM with the filter, heater and valves included is likely to be well over 70'. Without the pad equipement, it might be possible but then plumbing becomes a nightmare. Having a separate pump for the jets would make them work so much better. Besides, you really don't want that high flow rate going through the filter. Not good.

For the decents, a 1/2 HP Whisperflo will probably deliver close to 90 GPM or over 30 GPM for each decent. Head loss is fairly low since you have three runs and low flow rate per run so there is about 16' head loss @ 30 GPM in 2x50' of pipe with fittings.

Really your setup almost demands 3 pumps and anything less you will have to compromise on performance and features.

 

[dykes26]

8 Anzen Hydrojets with air line is what is says on the contract.

 

[mas985]

8 Anzen Hydrojets with air line is what is says on the contract.

Ask the PB what the flow rate requirements are for each jet.