Inground Spa Venturi(s) Not Working Well After Renovation - HELP

rpputney

Member
Mar 25, 2019
16
Texas
Hi TFP,

We did a renovation on our pool and the PB/Restorer left our job incomplete. One of the items that we need to fix is the 6 venturi jets in the spa.

We have a 30,000 gallon pool with a 9' deep end and and an attached spa as pictured here. The spa has a venturi on each end (2 total) that feeds 3 jets (6 jets total). There is also a new 2HP blower with 4 air outputs in the footwell of the spa. That works fine. We had the pool refinished with mini-pebble, new coping, and tile. There was a lot of debris that I cleared out of 1 of the 2 drains in the bottom of the spa. There was flow issues with the spinner jets that the PB/Restorer installed. We first noticed the spinners didn't all spin and only some would have ~25% of the bubbling they had before the renovation.

Here is what I did to try to get all 6 jets to flow and venturi bubble:
1. removed all 6 nozzles (end caps)
2. removed old 1/4 turn jet inserts
3. bought 5 new plugs with o-rings and both vacuumed and blew out the jet ports 1 at a time with the 5 plugs in the other ports.
4. removed drain covers and cleaned all rocks/sendiment left from renovation. I can run a small snake ~35' back to pump/equipment (which is ~60' away)
5. installed 6 new 1/4 jets
6. cleaned Pentair Sta-Rite System 3 filter & put in 6 cups of new DE
7. ran Pentair IntelliFlo at 3450 RPM (max) in SPA mode

When we do this, air bubbles weakly out of 2 ports on the left and 1 on the right. The pressure with the spinner nozzles on pulsates at ~50-75% what I think it should. I then tried this:
1. install original eye-ball nozzles --> a lot of water comes up the venturi air pipe valve if more that 1-2 of the eye-balls are installed. With the spinner nozzles no water comes up.
2. with spinner nozzles, blew shop vac air down venturi/air pipe one side at a time - those 3 jets bubble wildly on both sides.

I believe both of my drain lines are now clear. My filter shows 20 PSI at 3450 without DE and 24 PSI with DE (typical since we've had the pool). We did install a new heater that works fine, no leaks. Plumbing only changed slightly. For the SPA, the single pipe coming back to the equipment is 2" PVC and so is the single return line.

Can there be debris in the venturi (that went down the air pipe/valves when those pipes were open during demo)?
If not, I am thinking I have either a pressure or a flow problem but would like some expert advice or further things to try.

Your help and ideas are very much appreciated.
Rob and Alice.
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mas985

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Did the spa jets work ok before the reno?

What plumbing/equipment changed with the reno? Any plumbing, jets, pump, etc?

installed 6 new 1/4 jets
Are these 1/4" orifice jets?
 

rpputney

Member
Mar 25, 2019
16
Texas
Hi Mark, the spa jets did work before the reno.


These plumbing changes were part of the reno:
1. new heater (replaced old RayPak that had rusted out) and plumbing (see pic)
2. added a Jandy valve programmed feature for 2 sheers (had manual valve before)
3. replaced auto chlorinator (same place in plumbing, same unit type)
4. installed 2 new air valves in the spa
5. changed six 1/2" jet orifices, twist lock p/n 30-44-1T (see pic, believe they are same part)
6. removed 6 eye-ball directional 1/2" outlet fittings and replaced with spinner type

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mas985

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1/2" jet orifice will need a minimum of 25 GPM each or a total of 150 GPM which you will never get with that plumbing setup. With 2" pipe, I would use a maximum 5/16" orifice. I don't know how that spa worked before. Were the jets strong?

I believe they may reducers for those jets.

What is the distance between the pump and spa?

What is the pump height relative to the water level in the pool?
 
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rpputney

Member
Mar 25, 2019
16
Texas
Hi Mark,

The jets worked okay in the past with a both water mixed with venturi air bubbles. We never used the spa with the air valve turned off, so it is hard to compare the old and new water flow. Now we only have minor air mixed on 3 of the jets (2 on the left side and 1 on the right side) unless we force air in via a shop vac and that has all 6 bubbling like crazy. Both the old and new jet orifice openings are 1/2". So if we restricted the flow more by changing to the 5/16", it would increase the jet pressure. Any idea what it would do as far as the venturi function? Note that today when we change from the spinner to the eye-ball outlet fitting, if I do all 3 at one end, water comes up the air valve pipe. Even if I put in one eye-ball it will back flow through the air vavle. I wonder if having the 5/16" orifice would do that as well?

About 10 years ago we changed from a broken single speed pump to the Pentair IntelliFlo Model 011018 in 2012 which is 3HP and 180 GPM max at 30', 168 GPM @ 40' based on one place I read.

It is about 63' from the pump to the spa. I would estimate the pool equipment is about 1-2' above the level of the pool water (it is definitely higher as water will flow down to the pool from the equipment when I take the pump basket cover off to remove/empty the basket).

I know this seems complex, frustrating, and likely something simple is wrong, so I appreciate you talking through this with us Mark.

Rob
 
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mas985

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So if we restricted the flow more by changing to the 5/16", it would increase the jet pressure. Any idea what it would do as far as the venturi function?
Reducing the orifice size increases the water velocity in the jet which also increases the pressure differential in the venturi so it will suck in more air. So the smaller the jet, the more powerful the stream and the more air you get.

About 10 years ago we changed from a broken single speed pump to the Pentair IntelliFlo Model 011018 in 2012 which is 3HP and 180 GPM max at 30', 168 GPM @ 40' based on one place I read.
The head loss you have in your setup far exceeds those values. Based upon the information you have given me, my estimate of the operating point is about 83 GPM @ 86' of head. This about 14 GPM/jet which is less than half the recommended flow rate for those jets.
 

rpputney

Member
Mar 25, 2019
16
Texas
Reducing the orifice size increases the water velocity in the jet which also increases the pressure differential in the venturi so it will suck in more air. So the smaller the jet, the more powerful the stream and the more air you get.


The head loss you have in your setup far exceeds those values. Based upon the information you have given me, my estimate of the operating point is about 83 GPM @ 86' of head. This about 14 GPM/jet which is less than half the recommended flow rate for those jets.

That makes sense Mark.

Is there anything we can do to optimize the plumbing setup better? I did buy a new Pentair SuperFlo 340042 SF N2 1A 230V pump that is not in use. That wouldn't help to add that pump in to change the plumbing I assume.

I did a little searching and didn't find the 5/16" air jet nozzles or reducer. Do you have a link or can you point me to the part I can order to test that out?

Thank you.
Rob
 

mas985

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Adding a pump would not help. The best solution for your setup, without spending $$$$, is to reduce the orifice.

I know that Hydro Air makes reducers so you might contact Inyo and see if they can help.

Here are some others


They seem pretty expensive though. If you are handy, you may be able to modify the jets yourself. I have done this myself by filling the jet hole (just the tip) with epoxy and then drilling a new hole of a smaller size.
 

rpputney

Member
Mar 25, 2019
16
Texas
Hi Mark,

Your advice worked!

I have a neighbor that owns a manufacturing company and I gave him a drawing of what we wanted to do. We added a 1" long x 1/2" diameter pvc plug cemented into the end of the jet orifice and then put it on a lathe and drilled a hole to your 5/16" recommendation. He manufactured 6 of those today and I installed them tonight. It works perfect with the spinner jets at 3,450 RPM on the pump. It is even a bit too aggressive so we can back off the pump to 2900 RPM and it is perfect.

Note that we did try to install the eye-ball jets to see what that would do, but by the time I installed 2 of the 3 jet eye-ball heads (2 spinner and 1 eye-ball), the water backflowed through the air valve. So we are staying with the spinner heads. I wanted to add the short video of the jets in motion but couldn't figure out how, so I embedded the picture with all 6 jets running with sufficient pressure/volume and venturi air working.

Thank you for your advice Mark!
Rob and Alice
 

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