Pool-Spa pumps-jets

nukequazarJanuary 22, 2013

I'm remodeling my pool and adding a 6'x6' in-ground gunite spa. Looking for opinions about one or two pumps, and how many jets I can have.

1. I am planning on a Pentair Intelliflo VS 3HP variable speed pump. Pentair says this single pump will do the job just fine, but my plumber insists that I need two pumps.

2. I would like to have 14 jets, but my plumber says I can only have 8-10.

3. I like the idea of fancier, adjustable jets and air injection (the Venturi type, not a blower), but again, my plumber does not use either of those.

Opinions? Advice (besides get a new plumber!)?

Thank you!!!

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Your plumber is right about a few things.

First a blower is used on venturi jets as well. The reason a blower is used is because the air pipe is too long (>15') not because of the type of jet. All spa jets that produce bubbles are venturi and I would be surprised if your PB did not have that type.

A single pump will not be adequate for 14 jets. Even the smaller jets require 15 GPM/jet for moderate strength and some jets require up to 25 GPM so to design the spa properly, you need to decide on the jet first.

With the smaller jets, 14 jets would require 210 GPM which no single residential pool pump can deliver. You would need a minimum of two very large pumps on very large plumbing to support that number jets so think about this very carefully.

A single 2 HP full rated pump will at most support 8 - 15 GPM jets. The Intelliflo would be about the same.

    Bookmark   January 22, 2013 at 11:46AM
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Thanks, mas985! That all makes sense.

As for the bubbles, a Pentair tech told me that he uses Venturi jets that have a local passive air intake at the spa with a manual valve to adjust the air intake. I don't want to use a blower pump. Is it common to have a valve to control the air intake? I guess I thought you only had control if there was a blower in the system.

To be clear, the plumber wants to use two pumps regardless of how many jets. Even for just eight jets, he wants to use two pumps.

The reason I like the single pump concept is being able to heat and have jets with only one pump running to save electricity and it's quieter.

So, next thought: If I use two pumps, what if I have him put 5 or 6 jets on the primary pump (the pump that feeds the filter and heater) and then 8-10 jets on a second 3 HP variable pump? Would that work, and give me the most flexibility and jet power?

This post was edited by nukequazar on Tue, Jan 22, 13 at 14:46

    Bookmark   January 22, 2013 at 2:37PM
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My spa does not have a blower and does not have coping valves either. There are actually three ways to plumb a vent pipe for a spa and it depends on how far the equipment pad is from the pool and what you are looking for.

1) Use coping vent valves to have air adjustment at the spa. Note that changing the amount of air does not change the strength of the jet only the way feels (pulsating vs steady). The same amount of water flows out of the jet regardless of the air.

2) Use a single vent pipe from the spa to the equipment pad. Sometimes a blower is required due to the distance. There really isn't air control with this because if the distance is long, then without the blower, there are usually no bubbles at all.

3) Have a vent pipe close to the spa usually outside of the deck. This does not require a blower and there is not air control.

Next, two pumps does not mean he is planning to use both for the spa jets unless he has specifically told you so. Typically in a dual pump installation, one pump is used for pool/spa circulation/filtering/heating and the other pump is for the jets only so you need to make sure on what he is planning.

Next, having two pumps does not mean you can't heat the spa. They normally plumb in a separate line for circulation/heating which is why I brought up the point above.

Normally, I would put the Intelliflo as a circulation only pump that can be switched between the spa and pool. The other pump would be dedicated to the spa jets only. This save the most in energy costs when it comes to filtering the pool. There is no point in having the Intelliflo if it is dedicated to the spa.

However, you could also plumb the Intelliflo so it runs some of the jets too. But generally, it is not a good idea to have high flow rates through your filter and/or heater.

So if you really want that many jets, then I would go with three pumps. Use the Intelliflo for just circulation/heating/filtering and nothing else. Then get two high HP pumps to run the jets on separate loops without any other equipment so the jets can be powerful and efficient too.

    Bookmark   January 22, 2013 at 3:43PM
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A six foot spa doesn't generally have the wall real estate to get more than 6 or 8 jets.

Using two pumps on a 6 foot spa means it'll likely need four drains, two per pump. Drains are normally on the floor to one side and a vertical one on the side. They would be very cramped, even overpopulated so to speak.

If you really want a lot of jets, I would suggest a portable tub. They last about 10 years. How much does the "add spa" to the plan cost? If it's more than a few portable tubs...


    Bookmark   January 22, 2013 at 5:13PM
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Portable spa is definitely not an option. Spa is 6x6 gunite in the pool.

If I use two pumps, the plumber will put the filter/heater pump drains on the floor, and the jet drains on the walls of the foot-space.

Question: Maybe I'm missing something... I'm curious about why gunite spas are so limited in the number of jets. Typical fiberglass spas have 30, 40, 60, 80 jets. I don't want 80 jets, I just want about 14-16. Why is that a problem? Just wondering...

Ideally I would like four jets in an 8" square at two seat positions, and one or two calf jets at each of those two seats. Then at the other two seats, two jets each. That doesn't seem excessive to me, so again, maybe I'm missing something?

I really appreciate the help!!!

    Bookmark   January 22, 2013 at 5:43PM
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There are a couple of differences but basically, you need to design them the same way. Each jet has a flow rate requirement and each pump can only deliver so much flow. They need to add up.

A gunite spa is typically far from pump while stand alone spas (SA) have the pumps next to the spa so head loss is much higher for the gunite spa and for a given pump size has lower flow rates. Also a SA spa tends to use many more smaller jets. The larger the jet, the higher flow rate required to make it feel strong. Also, SA spas tend to have several pumps depending on the number jets.

You can't fight the physics. More jets = more flow rate = more or larger pumps.

    Bookmark   January 22, 2013 at 6:37PM
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That makes sense. Thanks, mas985. The distance must play a big role in the physics because I had a SA spa years ago with a heater, filter, and six jets all running on one little pump (don't know the HP). That's why it wasn't making sense that I couldn't have more than eight jets with this huge, high-tech new pump.

    Bookmark   January 22, 2013 at 7:02PM
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It can be the size of the jets too. A lot SA spas have smallish jets which don't require much in the way of flow rate. If you went with 1/4" jets, you would need only 10 GPM per jet but 140 GPM is still a lot of flow rate for a single pump. The size and type of jet can make a big difference so it would be best to settle on that first and then size the pump for the jets.

    Bookmark   January 22, 2013 at 8:03PM
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Yes. Good advice. Thanks.

Is there any negative to using the smaller jets? Or is it just that normally, a smaller number of larger jets have been used in gunite spas, while options and technology have increased in the SA spa market?

Many people on this forum, and the Pentair tech, say that single pump systems work fine for a limited number of jets. Is there a reason not to split the jets between the main pump and the auxiliary pump? That way, if one person is in the spa alone, or if only one person wants jets, then just one pump goes on to run those jets. When more jets are wanted then turn on the other pump...

    Bookmark   January 22, 2013 at 11:41PM
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Duplicate post deleted.

This post was edited by nukequazar on Thu, Jan 24, 13 at 0:48

    Bookmark   January 22, 2013 at 11:47PM
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The smaller jets have a smaller footprint on the body. The larger the jet and the larger the flow, the more of a massage feel to the jet. Small jets tend to have a more focused sharper feeling. Think of it as a person giving you a massage with one finger vs their whole hand. There is a difference.

Given the size of your spa, you really aren't going to have more than 6 people so why do you need so many jets? One larger jet per person is sufficient and what is done in most IG spas.

But if you want more jets then as I had suggested before it is best to keep the number of jets per pump around 6-8 but no more. Each pump should then have it's own loop (separate plumbing to and from the spa). If one of the pumps is also used as the filter pump, then I would also suggest a bypass around the filter and heater because you can easily damage a filter with high flow rates. Plus going through the filter and heater can reduce your flow rate significantly and make for weak jets.

A more optimal solution is to separate the filter function from the jets but that means a total of three pumps, two for the jets and one for the filter.

    Bookmark   January 23, 2013 at 5:28PM
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I've never been happy with one jet pounding my back. It makes you have to constantly move side to side to equal out the effect.

I'm clearly not alone, since the market for spa tubs and SA spas has pushed the jet number to where it's hard to find a four-person spa with less than 30 jets, and they go to over 80 for $3-4000. I'm not looking for 30 jets but I think it's silly to spend all this money and have one jet on my back. My 10-year-old bath tub has eight jets.

I would like to have four jets on the back and two for calves in one or two seats, then just one or two jets on the rest of the four main seats. I don't think it's a lot to shoot for.

I guess I'd rather have a massage from ten fingers than one baseball bat. :)

If it's not feasible then it's not, but I don't think it's weird that I want more than eight jets, in a world where spas with 40-80 jets are in installed every day.

Anyhow... All personal opinion and preference... Thanks for your input!

    Bookmark   January 23, 2013 at 6:10PM
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