How to Balance Spa Jets?

[zamazing]

Newbie question here. My pool/spa was completed late last year. The spa has ten jets and is supplied by two separate blowers and a separate pump. Not sure if the blowers are feeding separate jets in the spa or if they are working in parallel and connected to all 10 jets.

The bubbles and pressure coming out of the jets that are closest to the pool equipment (where the blowers are located) are significantly stronger than the jets on the side of the spa that are farthest from the pool equipment. Is this normal? Can the jets be adjusted to distribute the pressure more evenly?

Can this unbalance be because of a missing Venturi Nozzle? I haven't checked to make sure they were all installed.

 

[OldPoolMan]

Yes! A missing nozzle will cause total unbalance in jet flow and power.

 

[zamazing]

Thanks for that. I'm going to check to make sure all the nozzles are installed properly first. In case they are, are the nozzles available in different diameters to control the flow and is that typically necessary?


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[wjr75]

You can usually turn the outer collar on the jet to regulate the flow. Might give that a try.

 

[zamazing]

Well, I may have discovered a can of worms here. Hopefully you kind folk will help me troubleshoot this one. Here's the deal...

As I mentioned in my initial post, the spa has ten jets and is supplied by two separate blowers and a separate dedicated pump. I inspected all the venturi nozzles and made sure that they are all in place. I first turned on the dedicated jet pump (this pump is supposed to draw its water from two of the drains in the spa and return it thru the jets. Then I turned on the blowers. After about 45 seconds, I noticed that one of them kicked off. I unscrewed that blower and noticed that the see-through check valve was stuck. It would not push down and there appeared to be water in the lower part of the valve. When I forced the check valve down, high pressure water came gushing out of the top. I immediately turned off the dedicated jet pump and the water stopped gushing out.

I unscrewed the other blower to see if the same situation exists there, but the jet pump does not cause water to come up into that blower. I'm now wondering if the builder messed something up. I'd really like to know what I should be expecting...

 

[zamazing]

I tried to do some more troubleshooting on this today and just don't know enough about how spa jets are plumbed in order to figure out what's wrong.

My understanding of spa plumbing is that there are usually two parallel pipes feeding the Venturi valve at each jet, one pipe carries water, the other caries air, and the Venturi combines the two at the jet. The pipes form a complete circle around the spa and a T is used to feed in the air or water. In my case where I have two blowers, I'm guessing that two T's are being used into the air pipe from the blowers.

The fact that turning on the jet pump causes water to gush out of one of the blower lines makes me wonder if they connected the pump to the air line by mistake (where the 2nd blower should have been connected). Any thoughts?


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[zamazing]

I going to give this a bump hoping that someone here is familiar enough with pool and spa plumbing to give me some advice on this....

 

[Joshy]

Sounds to me like you have 2 separate 'air' circuits, likely 5 jets each, and you've got one or more fully or partially plugged jets on the 2nd blower 'circuit'. The plugged jet(s) are causing an increase in water pressure sufficient to cause water to back up the venturi into the air circuit and up and out the blower like you're describing. Try plugging a jet or two on the functioning circuit and the bubbles will disappear and eventually back up into the blower.

I had a similar problem with a friend's pool at the house he just bought. The fix was to drain the spa (into the pool of course) and look down the barrel of each jet. There ended up being a bunch of plastic debris lodged in several of the jets. The venturis weren't removable so I ended up turning the blower on while sticking a rod down the barrel and breaking up the plastic. Works great now!

 

[OldPoolMan]

The blowers are set on the air lines. Without a blower, the air lines will suck air into the jets through the venturi fitting on the jets. Plugs in the jets will cause water to backup thru the air lines. That's why the blowers have a check valve, to prevent water from backing up into the blower. I suggest that you take the blowers off the air lines and run the jets to see if water backs up or the lines suck air. Then we can go from there

 

[zamazing]

Thanks for the replies.

Joshy I originally had the same thought, that there are two separate circuits of 5 jets each, but as long as the pump is not on and the blower on that line (the one that shuts off) has enough time to clear all the water that has backed up in the line then all 10 jets are pretty evenly bubbling with just the one blower. So I have concluded that the plumbing was likely done so that the blowers are intended to work in parallel. Also, because all the jets do bubble pretty evenly, I don't think that any of them are plugged. It's only when the pump is turned on, that 5 of the 10 jets shut down, as does the blower pump because it can't push against all the water pressure build up from the pump.

OldPoolMan, I have removed the blowers from the lines. When I turn on the jet pump, the check valve on one of the blower lines has so much water pressure that the check valve actually pops out of the unit and water comes gushing out of the line at an extremely high rate. This only happens on one of the two blower lines. This is what is leading me to think that the pump is incorrectly connected to the air line that is supposed to be shared by the two blowers and that the second blower is connected to what should really be the water line. Does this make any sense?


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[zamazing]

I'm trying to get a better understanding of how my spa is supposed to be plumbed. so I put together this drawing that makes sense to me as a layman. Note that it only shows the return side of the equation, not the supply side. Does it make sense to any of you experts or am I way off base? http://i772.photobucket.com/albums/yy9/zamazing7/SPA Plumbing_zpsd19vvuqt.jpg

 

[zamazing]

Any feedback on the plumbing diagram?


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[zamazing]

I wanted to update this post for future reference just in case someone else runs into this issue.

I was able to convince my PB to meet with me to troubleshoot the spa before replacing the two blowers with a commercial blower as he had planned. We were able to determine that the spa had in fact been plumbed incorrectly! It turns out that the FILTER pump return was incorrectly plumbed into the AIR line and one of the two blowers was incorrectly plumbed into the WATER line. This is the reason the water pressure from the AUX SPA JET pump would pop the check valve and shut down that blower.

There is a way to tell if your pump is hooked up to the air side or the water side of your venturi valves. If the pump is correctly hooked up to the water side, then the water will flow like a fountain from the nozzle. On the other hand, if the pump is incorrectly hooked up to the air side of the venturi, the water will just spill out of the fixture with little pressure because it will be coming from the outside of the nozzle where the air is intended to be drawn.

 

[chem geek]

Thanks for letting us know what happened and how to check for this problem.

 

[OldPoolMan]

Sorry being late getting back in. But, yes, water coming up a blower line means that either a venturi nozzle is plugged and causing water to back up into the air line or the blower is plumbed into the water return line. I'm glad your PM got that solved.