In-ground Spool Plumbing

aaronc1976

Member
Jun 10, 2021
18
Simi Valley/CA
Hello and thanks in advance for any help provided. I am building a spool as an owner/builder and had some questions regarding plumbing. I say spool but this is basically a large spa. It is approximately 17 feet by 10 feet and 3.5 feet deep (single depth). Excavation is complete and steel is going in on Saturday.

I am trying to decide on proper plumbing pipe size. I have 2 pumps, one VS Intelliflo, 1 3 HP Whisper flow. A 420 cartridge filter and a 400,000 BTU Master Temp heater and a Polaris air blower already bought and paid for sitting in my garage.

The perimeter of the spool is about 54 linear feet and trench from pad to pool is about 25 feet. I want to put about 10-12 jets in here, nothing fancy just good action. I'm assuming standard jets would require 15-20 gpm per jet. We are planning on the following:

Suction lines from skimmer and drains at 2.5"
Air line at 1.5"
Two return lines one for each pump handling 5-6 jets each will have 2.5" up to where the loop starts and scale down to 1.5" for all jet connections

Would this be ok, or does the pipe size need to be bigger? Also, planning on placing second pump after heater so hot water continuously goes through all jets when spa is running.
 

cowboycasey

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Welcome to TFP :)

1. with 2 pumps they should be on there own pipes, both suction and return.
2 what pump will be connected to the heater?

I am not good at doing plumbing for spa's because of the air blower and extra plumbing... Here is mine for my pool..


1623408118455.png

1623408140127.png
 

aaronc1976

Member
Jun 10, 2021
18
Simi Valley/CA
Welcome to TFP :)

1. with 2 pumps they should be on there own pipes, both suction and return.
2 what pump will be connected to the heater?

I am not good at doing plumbing for spa's because of the air blower and extra plumbing... Here is mine for my pool..


View attachment 344045

View attachment 344046
Are you saying that I should plumb separate suction lines for each pump rather than having flow split exiting the heater and one to half the jets, the other to suction line in second pump and out the second return line to the remaining jets?

Doing what you propose, would I just split the main suction line to the two pumps?
 

cowboycasey

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1 pump for 1 suction line and 1 return.. you can not pull 2 pumps of 1 line... it is to much for 1 line...

Usually 1 pump will pull from a skimmer or 2 skimmers and the other pump will pull from a side suction in the pool... Like I said, I am not good at this I just know about it.. @mas985 can you help out with this :)
 

mas985

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May 3, 2007
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The perimeter of the spool is about 54 linear feet and trench from pad to pool is about 25 feet. I want to put about 10-12 jets in here, nothing fancy just good action. I'm assuming standard jets would require 15-20 gpm per jet.
So on the upper side that is 240 GPM total which neither pump can handle on it's own so the jets will need to be split 5/7 and you will need two separate loops.

Suction lines from skimmer and drains at 2.5"
Air line at 1.5"
Two return lines one for each pump handling 5-6 jets each will have 2.5" up to where the loop starts and scale down to 1.5" for all jet connections

Would this be ok, or does the pipe size need to be bigger? Also, planning on placing second pump after heater so hot water continuously goes through all jets when spa is running.

So you were planning on putting the pumps in series? That is a really bad idea. You will never get the flow rate you need.

To get close, this is what I would do:

Use 3" pipe for suction and return. 2.5" pipe for the air line. Have two loops. One from the MD to the Whisperflo and right back to 7 jets. The second loop is from the skimmer to the Intelliflo, filter, heater and back to 5 jets. This will be a bit more balanced and give you about 17 GPM per jet. This assumes 3/8" jets. The Whisperflo loop operating point would be about 121 GPM @ 78' of head and the Intelliflo would be about 86 GPM @ 87' of head at full speed.
 
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aaronc1976

Member
Jun 10, 2021
18
Simi Valley/CA
Thank you so much! This is helpful. We are going to notch out two more main drains and have dedicated suction lines for each pump. So, two pairs of drains feeding each pump with 2.5" suction lines. We are going to do 2" return lines from each pump and will run filtration pump through the heater like you suggested. I am going with Waterway Poly Storm jets which have 2 inch water inlets in the jet bodies. Each jet has a 10gpm spec.
 

mas985

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Note that you should only route the skimmers to the pump with the filter. You don't want debris pelting your back.

With a 10 GPM spec, the 3 HP Whsiperflo is going to have a lot of pressure/velocity and no way to control it. An second Intelliflo might be a better choice although I know you already purchased it.
 

aaronc1976

Member
Jun 10, 2021
18
Simi Valley/CA
Note that you should only route the skimmers to the pump with the filter. You don't want debris pelting your back.

With a 10 GPM spec, the 3 HP Whsiperflo is going to have a lot of pressure/velocity and no way to control it. An second Intelliflo might be a better choice although I know you already purchased it.
Intelliflo pumps are extremely difficult to come by right now. My local pool store says they are heavily back ordered and there is a waiting list. Will the Whisperflo harm anything? Can I get away with the Whisperflo until things calm down enough to source an Intelliflo without having to wait months?
 

mas985

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Pleasanton, CA
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No problem just lack of adjustability. The higher head loss in the jet is likely to reduce the flow to close to 10 GPM. But I would still put 5 jets on the Intelliflo and 7 on the Whisperflo.
 

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