New Pool Build - Want to Design for Efficiency and Perform

[bzeller]

Ok, I've read the Hydraulics 101 sticky about 3 times now. Not sure I grasp it all, but getting there. I'm still struggling a bit with exactly how to best size pump options, pipe sizes, # of returns, # of skimmers, # of drains, etc. I have 4 quotes for what is essentially a 35' x 16' rectangular pool with 7' x 7' spa. I don't have exact layout yet, but the nearest edge of the pool will be within 40 ft of the equipment and spa probably 50 ft. The pool and spa are out of the ground a little so my guess is there's probably a 2-3 ft elevation change from equipment to pool (pool higher). As for water features, there really aren't any other than a couple bubblers on the tanning ledge. The spa will have 6 jets, unsure of specified jet size, but plan to ask what is being quoted. The PB's have quoted as follows...

PB1
Pool Pipes - unto 2.5" PVC
Returns - 4
Skimmers - 2
AquaStar Main Drains - 5 (2 per pump + 2 per spa)
MDX debris removal drain - 1
Pentair WhisperFlo 1.5 HP
IntelliFlo VS-3050
Spa Pipes - 3 inch suction, 2.5" return
6 Jets Waterway Therapy
Pentair MasterTemp 400K NG
Pentair Quad DE 100
This builder quoted an in-floor cleaning system PV3 w/MDX & Leaf Canister - 25 heads. I'm leaning towards removing it due to cost.

PB2
Returns - 3, 2" PVC
Intakes - 2.5" PVC
2 split suction VGB approved main drains
2 Skimmers
Jandy Stealth Pump
Jandy 460 Sqft Cartridge Filter
6 spa jets
Jandy 400K Heater
Spa split suction drains, 3" suction plumbing
Did not specify return size plumbing

PB3
Returns - 4, 1.5" PVC
Drains - 2, 2" PVC
Skimmers - 2
2HP Jandy E-Pump
Jandy 460 sqft Cartridge
Spa Jets 6
Jandy 400K Heater
Nothing else specified

 

[BoDarville]

Re: New Pool Build - Want to Design for Efficiency and Perfo

bzeller:

What is the average depth of the pool you plan on building? Please provide that when you can to help us more accurately estimate the water volume. Also, will the spa be a spillover type (elevated above the pool with a spillway, or waterfall, into the pool) or will it be at the same elevation as the pool?

A few notes...

• 1. PB1 lists two pumps: A 1.5 HP WhisperFlo and an IntelliFlo VS-3050 whereas I'm only seeing one pump listed by PB2 and PB3. Is this a typo or am I missing something ?
  2. I side with your leaning on removing the in-floor cleaning system. Not only is there the initial cost, but potential repair costs down the road with all those heads along with the extra plumbing under the pool. Of course, you would need a pool vac to replace the in-floor cleaning system and could go with either a robot-type (e.g., Dolphin) or a pressure type (e.g., Polaris). My Polaris is around 15 years old, keeps the pool clean, and has needed only minor repairs in that time. I generally go with the simplest solution that will meet the need.
  3. I do not see a light listed by any of the PBs.
  4. PB2 seems particularly light on the number of returns. I would suggest a minimum of 4. If you plan on adding steps to the pool, I would add another return near them to keep fine debris from accumulating there.

 

[bzeller]

Re: New Pool Build - Want to Design for Efficiency and Perfo

Average depth will be approximately 4.5'. We originally planned on having the spa level with the pool, but have decided to raise it 6" providing a small, inexpensive water feature.

1. No, that's right. I think the only reason for the two pumps from the first builder are because it has an in-floor cleaning system. From what I can tell, most builders in the area specify one 2HP VS pump and recommend running at low RPMs to cycle the water and then ratchet the pump up and divert the water to the spa when turned on.

2. Yes, I've been doing some research on various cleaners. I lean towards the robotic cleaner, but agree simple may be the winner due to cost.

3. I didn't list all the items, just those I felt pertinent to the plumbing, etc. I've actually had each builder specify installing the light niche only and I'll purchase my own LED light. I've found I can get them much cheaper myself than paying PB mark up.

4. I asked him about this and he told me he checked with his engineer and they felt it only needed three. I agree, I'd like to see 4 but would like to provide some solid reasoning behind it as he has 20 years experience and I have about 2 weeks.

Also, we have what is approximately a 6 x 6 reef/tanning ledge in the pool. I'm thinking of specifying a couple simple bubblers which should help keep that clean.

Thanks,
Benjie

 

[bzeller]

Re: New Pool Build - Want to Design for Efficiency and Perfo

This is an interesting journey, a few other questions popped up today...

1. One PB told me that the light niches aren't sealed and the junction box for the lights are just placed a foot above water level. This would mean that the conduit is wet all the way back to the platform. I thought that was a little weird, but since he has 20 years experience I accepted that and found myself a Jandy LED 300W light with 100' cord that I told him I'd install myself in the niche. However, when I told a second PB my plan and asked him only to quote the niche sans light, he said when did I plan to seal the niche. I told him what I'd been told and he said that is wrong, that the niche is sealed with epoxy per national code and the conduit should never be wet back to the platform. Which is it?

2. The PB that specified 3" piping for the spa told me that once the plumbing reaches the interior of the spa, they reduce to 1.5" to run around the spa. That typical? There's not much length of piping in there so head loss should be minimal. I know they have to reduce at some point to get to the jet connection.

Thanks,
Benjie

 

[JasonLion]

Re: New Pool Build - Want to Design for Efficiency and Perfo

1) The niche is sealed to the pool wall, but water does get inside the niche and inside the conduit back nearly to the junction box. During normal operation the conduit is full of water. The sealing that is required is to prevent water from getting out of the pool where the niche attaches to the wall.

2) Some reduction is common as a loop is like having two pipes instead of one, so a somewhat smaller diameter is fine. But stepping down from 3" to 1 1/2" seems like a little too much of a step down to me.

 

[bzeller]

Re: New Pool Build - Want to Design for Efficiency and Perfo

1) The niche is sealed to the pool wall, but water does get inside the niche and inside the conduit back nearly to the junction box. During normal operation the conduit is full of water. The sealing that is required is to prevent water from getting out of the pool where the niche attaches to the wall.

2) Some reduction is common as a loop is like having two pipes instead of one, so a somewhat smaller diameter is fine. But stepping down from 3" to 1 1/2" seems like a little too much of a step down to me.

Awesome, thanks for the feedback. I really like the PB that told me the conduit would be wet, but after hearing the other PB was worried he was cutting some corners.

I looked and I found 3" PVC to 1.5" reducers. Unless there's just not room, can you tell why I wouldn't want 3" plumbing, both suction and jets all the way up until they had to reduce to 1.5" at the jet?

 

[mas985]

Re: New Pool Build - Want to Design for Efficiency and Perfo

1. It is normal to have a wet conduit back to the equipment, they just need a j-box above water level between the light and the service panel to isolate the water.

2. I would split the 3" pipe into a looped header around the spa and the tee that into the venturi jets with 1.5". Otherwise you will have decreasing pressure with each spa jet so the jets won't be equal in strength.

A couple of other recommendations:

For the spa, I would use 3" on both the suction and return. I don't know why some PBs use different sizes but it makes no sense.

I would separate the spa jets on a separate loop from the spa heating/circulation function. Spa jets require high flow rates and you really don't want that going through the filter. Even if you decide on a single pump, it is still a good idea to have a separate loop so most of the water is bypassed around the equipment.

 

[bzeller]

Re: New Pool Build - Want to Design for Efficiency and Perfo

By looped header you just mean a connected loop like in this attached drawing?

[attachment=0:1hgg9rqn]IMG_1291.jpg[/attachment:1hgg9rqn]

I can understand wanting to separate the jets from circulation through the filter, but in the single pump case, I would need the heater inline with the jets, correct? Help me understand this a little more. I thought the returns for a spa ARE the jets. For daily circulation, I pictured the pool and spa suction/returns are all tied together. When you turn on the spa, I assumed a valve shuts off the suction/returns of the pool, heater turns on, and the VS pump increases RPM to increase gpm to the spa for jets. In your example, there would just be another valve and 3" PVC run to bypass the filter?

You're all invaluable! Thanks again for the help.

 

[jblizzle]

Re: New Pool Build - Want to Design for Efficiency and Perfo

That is the idea for the loop.

Some spas have separate returns that are NOT the jets. You could do this with one pump by using a valve that diverted most of the flow to the jets, and left some of the flow through the filter and heater that would go to the circulation returns.

I think what you said means you actually get it ... you would not need 3" for the circulation returns, but would want it for the suction and the jet loop.

 

[mas985]

Re: New Pool Build - Want to Design for Efficiency and Perfo

Yes, that is a looped header although sometimes it can't go all the way around the spa so it loops back on itself.

I can understand wanting to separate the jets from circulation through the filter, but in the single pump case, I would need the heater inline with the jets, correct?

No. There will be a separate circulation loop with a separate suction and returns for the spa, usually two near the bottom of the spa. In spa mode, the heater/filter would be switched to this loop.

With a single pump, you would draw from a single suction line. I would still plumb the second suction line in case you ever want to go with two pumps. After the pump, there will be a three way valve which will control flow back through the spa circulation and the jets so can choose one or both.

But I would encourage you to use a second jet pump. The performance is better and you can fully separate the jets from the heater and filter.

 

[bzeller]

Re: New Pool Build - Want to Design for Efficiency and Perfo

Ok, I think I understand the set up you suggest. I'm going to look into a two pump system to see how it will affect the cost/efficiency curve.

Is the reason you're suggesting to bypass the heater because of dynamic head loss through the heater?

If I have a VS pump that can overcome that sufficiently, would it be a more cost effective, simpler set up to run the entire system off the pump utilizing the jets as your circulation system? In circ mode the pump would be running very efficiently at low RPM. Once spa mode was turned on, you'd shut down circulation of the pool, have a valve bypass the filter, and focus all available pump HP on driving water through the heater then to the jets. You could then avoid the extra pipe runs and cost of a second pump, right?

 

[mas985]

Re: New Pool Build - Want to Design for Efficiency and Perfo

Is the reason you're suggesting to bypass the heater because of dynamic head loss through the heater?

The main issue is both the heater and filter head loss, not to mention the other valves & fittings normally associated with the pad equipment. This will require you to have at least one size larger pump than you would need without them. Going through the pad equipment means less efficiency and higher energy use although for the spa, the jets are not run all that much anyway.

Also, high flow rates through the filter has the added disadvantage as possible damage to the filter although if you size the filter properly, you can minimize that risk.

If I have a VS pump that can overcome that sufficiently, would it be a more cost effective, simpler set up to run the entire system off the pump utilizing the jets as your circulation system? In circ mode the pump would be running very efficiently at low RPM. Once spa mode was turned on, you'd shut down circulation of the pool, have a valve bypass the filter, and focus all available pump HP on driving water through the heater then to the jets. You could then avoid the extra pipe runs and cost of a second pump, right?

Yes that is an alternative. However, depending the type of jet used, even a VS at full speed may not be enough flow rate. But also keep in mind the cost of a second pump and plumbing is not much when compared to the total cost of the pool.

 

[bzeller]

Re: New Pool Build - Want to Design for Efficiency and Perfo

Mark,

Again, thanks for the feedback. I'm glad I finally understand this better and some of the engineering behind it. As a EE major, who is now a sales engineer, I tried to avoid fluid dynamics and other similar classes like the plague! ;-)

Regards,
Benjie