Help selecting best venturi tee nozzle size

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B

bullngator

0
Jun 2, 2013
10
I have a 6x6 square spa with four jets connected via 2" PVC to intelliflow VS pump which is used used for both pool/spa. The venturi jets are connected to a 2" air pipe which extends approx 15' from my spa. Spa is located approximately 50' from pool equipment pad and is connected via 2” piping.

I noticed my existing venturi tee nozzles are 1/4" and assume I should I should swap these out with 1/2" or 7/16" venture nozzles to get better performance? Should I also change the return size on each jet? Return jet openings are 1.5” (rings w/o eyeball)?

If it matters venture tee nozzles are recessed approximately 10” behind the return jet opening.

Thanks in advance for recommendations.

-Brian
 
There are a couple of issues when going to larger jet sizes. First, in order to get the same exit pressure, you need higher flow rates for larger jets. This can be a problem because the plumbing may not support it. So for a 1/4" jet, you only need 7 GPM/Jet to achieve moderate pressure while for a 7/16" jet, you will need 19 GPM per jet. Since you have 4 jets that would be a total 76 GPM which doesn't sound too bad as long as the pump can produce that with the head loss in all parts of the plumbing.

If you can tell me the filter pressure when the pump is running the jets, I can estimate the flow rate of the jets with the old and new jets. Also what kind/size filter do you have?
 
Filter is a clean and clear 200 cartridge filter.

15 PSI @ 2,300 RPM @699 W
22 PSI @ 2,800 RPM @ 1,177 W
26 PSI @ 3,000 RPM @ 1,424 W
30 PSI @ 3,200 RPM @ 1,705 W

I am also attaching links to pictures of plumbing during construction. Return lines are 2" and I believe 4" on drain line connected to two VGB drains in spa floor.
Other plumbing in the photo is the blower line for floor air vents and retractable spa fountain.

http://1.bp.blogspot.com/-qSk5_cC0yu8/UDbB_AP4KqI/AAAAAAAAAKI/Eim8dgGLgSw/s1600/DSC_0407.JPG
http://2.bp.blogspot.com/-rMorId0Foyc/UDbCOk8GdPI/AAAAAAAAAK4/BVgHWmhIIv8/s1600/DSC_0427.JPG

Thanks for the help!
 
Are you sure the jets are 1/4"? The pressures that you posted are more indicative of 3/8" jets which are the most common type used in spas.
 
You have the full size Intelliflo and not the i1 or i2?

When running the spa, is any of the water diverted to other returns (floor or fountain) besides the jets?
 
The spa floor pipes are only for air? No water?

Do the jets feel really strong almost too strong at 3200 RPM?

Also, it might be helpful if you could post a picture of the pad equipment and plumbing.
 
Best I can tell, flow rate is around 60 GPM @ 3200 RPM which would be around 15 GPM per jet and should be more than enough for the jets so it is surprising that the jets do not feel that strong. But again, I was expecting much higher filter pressure for 1/4" jets so my first thought was that some of the water was getting bypassed around the jets. Something isn't adding up here and I am not sure what is going on.

Have you tried removing the jet nozzles and running without them? What is the filter pressure then?
 

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I removed jets. New ratings as follows. As it relates to my original statement I should clarify that jets always felt powerful. My assumption was that the opening on the venturi nozzles should be larger based on only having four jets and that this would up the performance. On another note my regular setting for SPA is 2,300 while it heats up. When operating at this speed my Intellichlor IC60 does not kick on (low flow). That leads me to believe I am just under or right around 25GPM @ 2,300 RPM.

Pressure w/o ventur T's (2" pipe to spa, 1 1/2: pipe in gunite wall with 1 1/2" return rings directing water into spa:

14 PSI @ 2,300 RPM @ 775 W
19-20 PSI @ 2,800 RPM @ 1,348 W
22 PSI @ 3,000 RPM @ 1,665 W
24 PSI @ 3,200 RPM @ 2,035 W

Thanks again for all the help!
 
15 PSI @ 2,300 RPM @ 699 W
Click to expand...
That should be resulting in about 45 GPM so the SWG should be fine with that. The Intellichlor normally has a bypass with a small check valve. If that isn't closing at the lower flow rates, that might explain why there is not enough flow rate.

As it relates to my original statement I should clarify that jets always felt powerful. My assumption was that the opening on the venturi nozzles should be larger based on only having four jets and that this would up the performance.
Click to expand...
If the jets are now powerful, I don't understand this statement. Exactly what are you trying to achieve. When you widen the orifice in the jet, it will generally make the jets fell less powerful unless you can increase the flow rate to the jet.
 
If I bypass the heater my readings are as follows in SPA mode (with venturi T nozzles removed):

9 PSI @ 2,300 RPM @ 876 W
15 PSI @ 2,800 RPM @ 1,510 W
17 PSI @ 3,000 RPM @ 1,822 W
19 PSI @ 3,200 RPM @ 2,205 W
 
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