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Pool + Spa - One Pump Or Two?


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#1 JoelG

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Posted 11 December 2006 - 09:30 AM

Howdy ya'll,

I'm new on the board. We're in the planning stages of a new pool, and talking to a couple of pool companies. The pool will be approx 35' x 14'. It will have a 6x7 spa at one end that spills over into the pool.

Company A gave us a bid with a single pump -- a 1 HP Jandy which would operate both pool and spa. Company B says they'd use a 2HP pump to drive the spa, and another 1HP pump for the pool filter.

Other than a bit of added complexity, is there any reason I wouldn't want a 2 pump system? Is a 1HP pump adequate for a spa?

Thanks in advance!
-joel


#2 Pool Owner

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Posted 12 December 2006 - 08:22 AM

The biggest reason to consider a separate pump for the spa is to provide water to additional jets. The typical rule of thumb is 0.25 HP per jet. Therefore, 4 jets for a 1 HP pump used for both pool and spa option, and 8 jets for a dedicated 2 HP jet pump.

On the down side, it takes a little more electricity to run the bigger pump. Also, you will probably need to run the circulating 1 HP pump to heat the spa since two pumps typically have their own piping system (circulating pump connected to both the pool and spa AND heater).

For my two cents, your new pool is a significant investment and it is not easy to change the number of jets after the fact, so get both pool builders (or the one you like best) to explain the differences and why they recommend the choice they made. When I had my pool built, the contractor I selected provided a basic pool construction cost, then provided the cost of extras (many we ask about) so we were able to pick and chose.

If you have not yet done so, check your local library for books on the subject of building a pool. I have a short review of two books on my blog (noted below) and I have not yet gotten around to reviewing “The Swimming Pool” which another book I like that geared towards new pool construction.

Pool Owner
Orange County, CA, USA

#3 DKN1997

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Posted 14 December 2006 - 04:09 PM

Howdy ya'll,

I'm new on the board. We're in the planning stages of a new pool, and talking to a couple of pool companies. The pool will be approx 35' x 14'. It will have a 6x7 spa at one end that spills over into the pool.

Company A gave us a bid with a single pump -- a 1 HP Jandy which would operate both pool and spa. Company B says they'd use a 2HP pump to drive the spa, and another 1HP pump for the pool filter.

Other than a bit of added complexity, is there any reason I wouldn't want a 2 pump system? Is a 1HP pump adequate for a spa?

Thanks in advance!
-joel


We have been building pool/spa combos for 20 years using seperate pumps. We started out by using a 1hp or 1.5hp pump (2" lines) for filter pump, then [2] 2hp pumps for 8 booster jets in the spa. each booster had it's own dedicated 2" suction and the returns were tee's together in a loop in the spa. then we discovered that while we get good flow, it's a bit overkill trying to push that much water through 8 tiny orifices in the spa heads. We then moved on to using a single 3hp booster with a 3" suction and a 3" return bushed down right at the spa itself. This flowed just as well as the previous 2 pump arrangement.

Now, We have done some a third way, we will use a single 2.5 hp pump for the filter and heater, but now the spa filter suction line is 3", and in between the pump and filter is a valved bypass that connects up to another 3" return going back to the jets. this avoids putting too much water through the heater/filtr, yet lets you use a large enough pump to get the "action" you want in the spa. Definately not energy efficient.

i will say that with our customers, energy consumption is not an issue that they ask about. So in your case, the two speed pump would be pretty good. with the right bypasses and controller, you could run it on low speed in pool mode and move valves and switch to hight speed in spa mode.

in my opinion, a 1hp pump is not enough to get good flow out a spa like the size you are talking about.

also, I mentioned 3 ways to do it, there are probably a few more. out of your two proposals, company b's seems better to me. go with that and maybe subsitute a two speed pump for the filter system.

another added benefit from my standpoint (service manager) I like the two pump system because if you use the same model pump, in a pinch if the filter pump goes down, you can always swap the booster pump for it on the pad to get a customer through a holiday weekend if you have to order a pump or it's 8pm friday night, know what i mean?

No matter how you go, I would ask the builder to run at least 2" lines for everything. this way you can change pump sizes to get the flow you want. one thing you can never do is get more water through a skinny pipe, the laws of physics are against you there. you can always easily solve a high water flow problem by downsizing a pump, but you cannot solve a poor waterflow problem by upsizing a pump with too small of a line.

#4 JoelG

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Posted 15 December 2006 - 06:45 AM

Pool Owner,

Thanks for the informative reply. The .25HP/jet rule is very good to know.

Your suggestion of going to the library and checking out pool books is a good one. I buy books for just about everything I do, and yet it never occured to me to look for a book on one of the most expensive purchase one can make. blink.gif

Love your blog too. Lot's of good information there. You're just an all around good guy. smile.gif

Best regards,
-joel


#5 JoelG

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Posted 15 December 2006 - 07:29 AM

DKN1997,

Great stuff here. It was helpful to hear of the various approaches that you've taken over the years based on your experience. Good point that a two motor system gives you a built-in spare in case your filter motor burns out. Sounds like a single motor ain't gonna cut it, especially a 1HP. I do know he uses individual 2" lines for everything, so maybe he's thinking I could upgrade the spa pump in the future. I'll take your advice and ask him more questions.

Best regards,
-joel


#6 DKN1997

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Posted 15 December 2006 - 05:42 PM

DKN1997,

Great stuff here. It was helpful to hear of the various approaches that you've taken over the years based on your experience. Good point that a two motor system gives you a built-in spare in case your filter motor burns out. Sounds like a single motor ain't gonna cut it, especially a 1HP. I do know he uses individual 2" lines for everything, so maybe he's thinking I could upgrade the spa pump in the future. I'll take your advice and ask him more questions.

Best regards,
-joel


Hey Joel, actually a single motor should cut it, but you have to know what you are doing when it comes to plumbing the filter system for it. with the correct check valves and properly sized plumbing and tees', a single 2-3hp pump should do fine. We rarely use 2 speed pumps, so I am not up to date on what the ratings are for low/high hp. If you could get one that ran on 1/2 or 3/4 hp on low and then could switch to 2 or 3hp on high, that would be chaep to run, it might not be cheaper to build, though ,since you are adding costs for extra valves, check valves, and a 2 speed pump is more expensive than a single. you do save on some plumbing running from filter system to spa, so it might be a wash.


#7 homermex

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Posted 31 December 2006 - 08:35 AM

my pool was finished in september. The only change i would make to it is add a another pump for the spa and more jets.

#8 JoelG

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Posted 03 January 2007 - 01:41 PM

my pool was finished in september. The only change i would make to it is add a another pump for the spa and more jets.



Hey Homer,

Thanks for the input. I think we've pretty much made up our mind at this point to use pool company B, and go with the 8 jets and 2HP dedicated spa motor. It turns out the first guy (company A) was planning on 4 jets powered by the 1HP pool filter motor. That doesn't seem like enough.

Enjoy your pool.

Regards,
-joel


#9 Working man

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Posted 05 January 2007 - 01:22 PM

You will clearly need a seperate booster pump for the spa

Be sure to use a 2 hp pump and you will love your spa

good luck



#10 Poolboy

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Posted 10 January 2007 - 06:51 PM

Howdy ya'll,

I'm new on the board. We're in the planning stages of a new pool, and talking to a couple of pool companies. The pool will be approx 35' x 14'. It will have a 6x7 spa at one end that spills over into the pool.

Company A gave us a bid with a single pump -- a 1 HP Jandy which would operate both pool and spa. Company B says they'd use a 2HP pump to drive the spa, and another 1HP pump for the pool filter.

Other than a bit of added complexity, is there any reason I wouldn't want a 2 pump system? Is a 1HP pump adequate for a spa?

Thanks in advance!
-joel


The single pump vs multiple pump question only matters if you want to run multiple features at the same time. You can't operate your pool, hot tub, waterfall, and pool cleaner all at the same time unless you have a multi pump system. A single 2.0 pump may be fine for a pool / spa / pool cleaner situation but understand that you can't effectively run the pool cleaner and the (heated) spa at the same time.

Keep in mind that your pool builder needs to understand hydraulics and the flo rate / demand each feature of your pool requires. Don't let a company tell you a 1.0 will run the pool, the spa, and the cleaner.

Most "reputable" pump manufacturers have a rating system on their web sites for pumps and the requirements of each of the features they offer. Think of it like a battery - a 1.5 volt battery would not work for a light that requires 3.0.

But, unless you have a waterfall or other feature, I'd opt for the single pump system. At $500 + per pump in come cases, its less $$$ to repair, install, and replace if a problem occurs years down the road.



#11 custom97

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Posted 11 January 2007 - 10:07 AM

Check out the Intelliflo pump by Pentair. They have 2 versions, one is totally programable and the other (4X160) has 4 speeds that can be programmed into it. @ 15 to 20 gpm per jet, these pumps will accomodate your pool and spa. They cover a range from .5 hp to 3 hp pumps, and if your plumbing is good can give a flow rate of about 160 gpm.

#12 randy

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Posted 23 April 2007 - 02:07 PM

Intelliflows a great option. I would never suggest a single pump pool/spa setup. The big 2hp pump is hard on all the other equipment not to mention the electric bill. Plus when your filter begins to get dirty your pressure will drop in the spa, with a 2 pump system thats not an issue.




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