New pool build -- pipes and pump sizes

[jasontx]

I am just starting the process of building a pool in Dallas. Most of the pool builders I've talked to here are sold on big pumps and small pipes -- which seems to be the opposite of what is recommended here. The pool design is for a 33'x17.5' 3'-5'-4' configuration with a 7' diameter spa, which I think works out to about 13k gallons. 2 skimmers and 5 returns, 6 jets in the spa. Am I in trouble with the skimmers being plumbed separately back to the pad but with 1.5" pipe? I'm not sure about the return plumbing. The spa is all 2". Currently spec'd is a 2.5 HP Jandy pump and a 1 HP pump for the water features (3 12" scuppers). They feel the 2.5 HP is necessary to run the 6 spa jets.

So does the separately plumbed skimmers make up for the 1.5" pipe or does everyone do that? It's just weird when the several PBs I talked to locally all seem to do things pretty much the same and it is different than is discussed here.

The PB is in the process of switching from Jandy to Pentair, so I might be able to switch to Pentair equipment with the Intelliflo 4x160 (for an upcharge of course). I'm kind of neutral on the Jandy vs. Pentair thing -- I think they both make good equipment. If I got the 4x160 I can expect some energy savings and their cartridge-y DE filter looks interesting (you can backwash or pull out the 4 cartridges and wash them off), but Jandy's PDA looks nicer.

I'm even more concerned with the plumbing and the Intelliflo 4x160 (that can pump 160 GPM and seems to like big pipes), especially since I would be one of my PB's first installations of it. Maybe they plan on automatically using bigger pipes when they go with it -- my salesguy wasn't sure. Hopefully we start the dig next week.

Sorry for the length of this. As I'm a newbie I've been reading all the great information here for awhile. I appreciate any advice you have to offer.
Jason

[eljefe281]

I suggest on insisting upon (at least) 2" pipe everywhere, unless smaller is required local to a particular item (for example, to connect to a 1.5" return).

One other thing to consider. Most builders want to use the main circulating pump to feed the spa jets. This has the effect of oversizing your circ pump. Since you will run the circ pump far more than the spa, this will increase your operation cost.

I added a separate pump dedicated to the spa jets. This will cost more, of course, so you'll have to see if your budget allows it.

I have a two speed, 1 HP main circ pump and a single speed, 1 HP spa jet pump (plus a waterfall pump).

The benefits of this arrangement include:

- Not having to use 2 HP worth of pump while the spa is heating up (you don't run the jet pump until the spa is warm enough for you to get in).

- Being able to operate the spa as a "hot tub" (no jet action other than the very little bit of agitation provided by the circ pump pumping through the non-jet returns). To me, this is really a nice benefit.

Let me know if you'd like me to send you my plumbing diagrams.

[ehorn]

Wow that is the first I've heard of a PB using 1.5" pipes. Every builder in Tucson here has wanted to use 2.5" pipes. I'm not an expert by any means in pipe sizing for different equpiment. Seems you are better off with pipes that can handle higher water flow. The difference in cost for pipe diameter is almost negligable.

Good luck with the pool!

[jasontx]

I don't understand the 1.5" either when looking at the posts here, but I talked to multiple builders and they all said the same thing. That is why I am questioning that maybe the fact that they were running separate lines makes up for it. It is hard to imagine they are building that many pools and don't know what they are doing -- these are companies that build 300-700 pools a year. I will push hard to upgrade to at least 2" everywhere.

I asked every pool builder I talked to about 2 speed pumps and they all glazed over. My thought on that was build it as they usually do and when I gain more knowledge, replace the pump if I understand it well enough and think the savings will outweigh the cost.

I've read about your pool build eljefe, your pool looks great. So can a 1 HP pump drive 8 spa jets? They wouldn't allow me more than 6 even with the 2.5.

Thanks for the answers.

Jason

[eljefe281]

I've read about your pool build eljefe, your pool looks great. So can a 1 HP pump drive 8 spa jets? They wouldn't allow me more than 6 even with the 2.5.

Thanks for the answers.

Jason

Thanks for the kind words.

I have a 1 HP pump feeding 8 spa jets and they are plenty strong for my taste. I also have a blower to juice them up when I want more action.

Each of my jets is designed for 13 gpm, so eight of them would require 104 gpm. Remember, if you have a separate jet pump, you won't have the pressure drop of the filter, SWCG, heater, and three-way valves in that circuit, so a given sized pump will deliver more flow.

I looked up the outlet pressure that the jets are designed to operate at, added some pressure drop for the piping and the jets themselves, converted the result to feet of head, and selected a pump by reviewing the pump curves.

In any event, I can't imagine needing more than 1.5 HP for a spa jet pump service (separate from the main circ pump).

[mas985]

Just thought I would add my 2 cents here. I also have 8 jets on a standalone 1 HP pump but I wish I had a bigger pump. My jets require about 15 GPM each which is a total of 120 GPM. With the head loss I have, even with 2 1/2" pipes, I get about 13 GPM per jet and it is not as strong as I would like. So double check the jet rating to make sure you will be getting enough pressure and flow to the jets for your liking. Some people like strong jets and some weaker.

A variable speed pump would give you some flexibility to choose your strength but they cost over twice a standard pump.

On pipe size, you can actually get away with 1.5" pipes as long as you have parallel runs from the pool to the pad and you use all 2" piping at the pad. So each skimmer, main drain and return has it's own pipe. You can equate the number of pipes with the following equation derived from hydraulics:

Equivalent Diameter = Pipe Diameter * N ^ (2/5) ; where N is the number of pipes

So 2 1.5" pipes is about equivalent to a 2" pipe and 3 is close to a 2.5" pipe.

I think it is a better design to have separate lines to each suction and return port and a ball valve for control reasons but I would still go with 2" lines for each instead of the 1.5" lines to reduce head loss even further.

Some builders like to use a single 2.5" suction line from the pool to pad and a single 2" return line from the pad back to the pool. This however, does not allow you to isolate the main drain into the pump for draining and it is more difficult to control the flow in each of the skimmers.

If your builder is suggesting a single 1.5" line for the suction and return lines (1 each), I might look for another builder since he really does not know what he is doing. But then again, most builders don't. That's why I contracted my own pool.

[jasontx]

I know each skimmer is a separate 1.5" line, and the drain is separate but I'm not sure if it is 1.5" or maybe larger (it is also an MDX drain so it has a single floor drain and side wall drains so the way that ties in I don't know).

So I guess that is kind of my question. Is 1.5" still bad if you have at least 3 separate lines to the pad for your suction? You get the sense that pools are built somewhat differently in different parts of the country and I just want to make sure that I am focusing on real issues -- because there are plenty of other things to worry about in a pool build.

The pump thing does seem off. Although if you had a big pump and big lines and you could do your 1 to 2 turns in less time is it really all that much worse? I guess it is better to have longer times of circulation at lower rates. While the non-HP centric Intelliflo seems like it could get me out if some of that, I worry if everyone here builds normal pools oddly how will they handle next generation stuff?

[mas985]

If I had to choose between 1 - 2.5" line and 3 - 1.5" lines, I would probably choose the later since I would have some control over each line that way. 3 - 2" lines would be even beter but make sure the lines are dedicated to each suction port (i.e. not shared) and they go all the way back to a large header at the pad. For three lines, a 2.5" header should be used although you could get away with 2" since the pump, heater and filter are all probably 2" anyway.

Shorter turnovers are not that bad but if I had my choice, I would design the pool with longer turnovers/run times. Skimming, chemical distribution and filter all seem to work better with longer run times and lower flow rates. So to save money, it is best to design with longer turnovers.

Ideally, I would design for the low speed of the pump for a 12 hour turnover so I could run at low speed 24/7 and still have 2 turnovers. Also, that would allow for up to 4 turnovers a day at high speed if you really needed it.

However, with 13k gallons you only need 18 GPM for a 12 hour turnover. Even with the lowest HP pump available at low speed, you will still have much more than that. However, the Intelliflow may be able to get that low and you could still use it for the spa with multiple strengths for jets. Even though it does cost a lot, it may be your best choice as it has the most flexibility and allows you to get away with a single pump for your entire pool and spa.

[divnkd101]

Jason,

Congrats on choosing to build a tool. As Mas has stated, I am putting in my 2 cents worth as well. Eljefe and I built our pools about the same time. I am plumbed with 2" throughout my pool and plumbed 2.1/2" in my spa. I was given a free upgrade on my pump (Northstar 3HP). Everybodies eyes popped out of their head when I mentioned that. However, I love alot of agitation in my spa and I made that perfectly clear to my builder from the get-go. I have heard alot of people talk of savings on electricity. I can turm my pool over 3-4 times within a 5 hour period. My electricity bill jumped about $90/ month when I first started my pool running it 12-15 hours a day. I am now down (winter time) to running it 3-4 hours a day with good water chemistry. My electricity bill is up about $30/month from average. I have compared to other neighbors with smaller pumps and there is not much of a difference between 1HP/ 2HP/ and my 3HP. Is my 3HP overkill?? Probably so, but I love my spa and I love the fact that all 8 of my jets are perfectly balanced. Good luck on your build and keep us up to date.

Divnkd101
22 x 36 Custom(21K gallons)
8' Spa
SWG
Polaris 280

[jasontx]

Thanks to everyone who replied for all information.

As my quote was for Jandy before they switched to Pentair (they told me they would be changing in the future), it would have been $1600 to switch to the Pentair system and get the Intelliflo pump (I never got whether it was the full Intelliflo or 4x160). In either case I'd gotten used to the idea of Jandy and decided to stay with that. I did upgrade to a 2 speed pump and the relay to control it all from the PDA -- so hopefully I should get the power for the spa and the efficiency for the pool. The spa will be plumbed with 2.5" (I was wrong about the 2"), the pool will have 3 separate 1.5" lines and I've decided to live with that. I kind of feel liked I've pushed them out of their normal bubble enough (I know not a good reason) and I think the three separate lines should be sufficient. I definitely get the feeling no one else usually questions choices / requests changes, but that interest is what makes us all more particular.

The dig will start either Friday or next week depending on weather. Even though I feel like I have already learned so much here, I'm sure I will have many more questions and hope to contribute when I'm a little smarter about all this.

Jason