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Pool new build

Posted by fordstar (My Page) on
Sat, Jan 5, 13 at 19:13

Would love any thoughts on our selections. It's our first pool!

40' x 20'
3.5' to 7' deep
7' round diagonal spa with negative edge spillway (7 jets)
4 columns along 36" high back wall
Two - 24" sheer descents on back wall
Splitface travertine and travertine tiles on columns and back wall
Pebbletec or SatinMatrix Pebble pool finish
Stamped concrete decking
Travertine coping

Pentair Intelliflo VS (3HP) for pool/spa
Pentair Whisperflo 1HP for water feature
Pentair Universal 3/4 HP booster
Pentair Clean/Clear 420 filter
Master Temp 400k btu heater
Polaris 280 cleaner
Rainbow 320 chlorinator
Silencer 2HP blower
Paralevel auto water leveler
ComPool 2 way and 3 way valves
Pentair Bermuda skimmers (2)
Dual anti-vortex drains (6)
7 returns
Pentair Intellibrite LED lights (3 for pool/spa)
Pentair Easy Touch 8 function control w/ wireless remote

Plumbing:
2.5" suction, separate lines, separate valve, PVC schedule 40 on all piping and pump connections, drains as needed to run to street, autofill line and overflow drain, water connection via backflow preventor
Structural:
4 bar box beams #4 rebar, walls/floors - #3 6"x6" on center, 6-to-1 cement-to-sand ratio, 12" min and 8" cove gunite beam thickness, 6" min walls/floor gunite thickness, #3 rebar on 16" centers for decking

$63,000


Follow-Up Postings:

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RE: Pool new build

You've got some great stuff going on with the bid, but no way to really check price without pertinent equipment runs, electrical runs, gas runs, deck square footage, etc.

One thing that stands out to me is the size of the filter- I would push for the 520 clean and clear with a 31k gallon or so pool. Both will suffice with given turnover rates, but you'll like the larger filters. A $150/$175 difference, but worth it in my opinion.


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RE: Pool new build

Your plumbing is undersized for the pump. I hope that the 2.5" is not for the spa suction or return. Even if it is for the pool skimmer it is undersized.
Go with the bigger filter like Natural One suggested. It's worth it.


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RE: Pool new build

Thanks Natural One and Pools94. I'll definitely discuss the filter with the PB. What do you recommend for the plumbing if the 2.5" is not sufficient?

Thanks again for your help!


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RE: Pool new build

Since the Intellflo pump rarely runs at full tilt, the 2.5" suction lines will be fine. The reason the pump is a 3 HP motor is to be able to use a larger impeller. The max speed can easily be governed so the motor doesn't push too much water.

Unless the equipment is more than 50' from the spa, a 1.5 HP blower will be fine for most spa jets. Pushing too much air can cause the blower to create excessive heat and shorten its life.

Make sure the Rainbow 320 is set for the high feed, not the stock low feed out of the box. The tube used to reach the high feed connection is included so it is easily done.

I like the Legend better than the Polaris. It keeps everything Pentair and gets the advantage of the extended warranty.

I agree with natural_one about getting a 520. The larger cartridges will require less cleaning frequency.

Scott


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RE: Pool new build

poolguynj,
I not seeing your point about keeping the smaller plumbing. The pump is rated to go to 3HP. If it has that capability and if you want to turn the pool over in 2 hours for any reason then your plumbing is undersized. Can you say the homeowner or pool service person will always keep the pump running at lower speeds? That's assuming a lot. Assumptions are the mother of all lawsuits.


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RE: Pool new build

I can't think of a reason to turn a pool in two hours. Add that to the fact that the insides of all residential filters never exceeds 2" plumbing, you'll never get the throughput a 3" suction would give you.

The motor in the Intelliflo is actually rated to 6 HP but the controller is current limited. Just an FYI. Zodiac/Jandy uses the same motor too but further limits the current and impeller down to the equivalent of a two HP motor

Scott


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RE: Pool new build

Suction velocity is always designed to be lower than effluent velocity. A 36 inch sand filter (144 gpm) 72 sq ft DE (144 gpm) and any cartridge filter over 300 (150 gpm) sq ft have 2 inch piping. The highest velocity would be around 14+ ft per second for just a few ft of exposed pipe on the effluent side of the pump which would be nominal in the head calculation. When you start exceeding 6 ft per second for a length of 50 ft on the influent side you will have a considerable impact on the total head and risk cavitation along with dangerous entrapment velocity. Unless you are trying to save a few bucks by cutting corners, it is always best to err on the side of larger pipe on the suction side of a system.


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RE: Pool new build

Agreed that influent water velocity should be slower than effluent velocity, few applications need more than 90 GPM. With 2.5" pipe, the head loss is about 5.3 feet of head per 100' of pipe. That is well within code for suction lines.

While an Intelliflo can run faster, the reason for the Intelliflo is to run it slower, reducing the amount of current it draws substantially. Governing it so that it doesn't exceed the flow rate of the pipe works.

While many filters advertise much higher flow capabilities, these speeds will introduce significant head losses due to the water's velocity. As it is, a clean filter with 2" internal plumbing will, at 90 GPM, introduce over 12.5 feet of head and it only goes up from there as it gets dirty and or the water velocity increases. Slower water through the filter yields a cleaner water when it leaves than trying to run it at full load.

The manufacturers look at the max flow from a "How much pressure can I put through it" point of view while a designer should look at it as what is reasonable.

Add the added head loss of a 2" plumbed salt cell and the head loss rises significantly. This can lead to an inefficiency due to water velocity where the cell can't make it's rated amount of chlorine because it isn't there long enough.

Add a heater and a bypass would need to be plumbed to ensure the water velocity and pressure aren't exceeded.

Running an Intelliflo at full speed will generally exceed the capacity of the drain cover because the water is moving too fast. Extra care needs to be taken to ensure no swimmers are in the pool when this is happening, usually during draining to lower the level, such as after a heavy rain or for intentional dilution purposes. It should also be a consideration for the spa.

If the drains are also plumbed to be returns for the purpose of heating, add a 3rd skimmer as they will be the only suction source and two may not provide sufficient flow to the pump when running at higher speeds.

Scott

Here is a link that might be useful: Head loss chart


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RE: Pool new build

You just said it. "Running an Intelliflo at full speed will generally exceed the capacity of the drain cover because the water is moving too fast. Extra care needs to be taken to ensure no swimmers are in the pool when this is happening, usually during draining to lower the level, such as after a heavy rain or for intentional dilution purposes. It should also be a consideration for the spa." If you have nine jets and your pushing 180GPM through the pipes at the max power the pump will get up to then you have to have at least a 4" suction and return to be in a safe zone for suction and return. Head loss through equipment is minimal compared to the total run for pipes and fittings. I calculate my pipe sizes too be no more than 4.5 FPS Suction and 6.5 FPS return. Extra safety and extra flow. I use the new XF 3 way valves and 3" plumbing on my equipment sets. The new XF variable speed pumps and the new XF filter cartridge coming out all have 3" inlets and outlets. No more excuses for under size plumbing.
You can't go to the lowest denominator on your plumbing sizes. There is no telling what people will do with there pools or equipment.


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RE: Pool new build

Well. the OP only has 7 jets in the spa and I think your flow through them is excessive for most jets. I typically see 12 to 15 GPM, not 20 per jet.

Until the XF series is complete, it doesn't provide a whole lot of benefit. That includes a salt cell and maybe a heater and heat pump but a bypass can be configured to open the plumbing around those when higher pre-programmed speeds are configured and used. We don't want too much water flowing those. When the XF series is complete, it'll be the cat's meow, that's for sure.

Scott


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RE: Pool new build

Thanks Poolguynj! I read a lot of your posts, and appreciate your insight and expertise. Will talk to my PB about the Rainbow 320, Legend cleaner and 520 filter.


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RE: Pool new build

With the use of a variable speed pump, I do urge you to consider using a salt cell such as Pentair's Intellichlor. With a VSP, the flow of water is significantly reduced for any erosion based tablet feeder and so, the amount of chlorine is also reduced.

Scott


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RE: Pool new build

What a nice big pool, but 40 feet long and only 7 feet deep?


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