Solar panel - LOTS of bubbles in the return jets

[dayhiker]

And that is with a dirty filter, correct? That is really low for an uprated 1.5 HP pump. Can you describe your plumbing to me? Lengths and number of runs pool to pad, pipe size?

It is dirty.

With solar off:
Pump to first return jet (this is the one with the bubbles. This is also the one that practically turns into a hot tub when the solar is kicked on due to all of the air that's getting pushed out)....My guess is maybe 15'-18'. The next jet on that side another 10' and the next another 10'.

with solar off:
I'm going from memory, vertical maybe 10', horizontal maybe 35, vertical maybe 10, horizontal maybe 14, then into the panel, so that would be about 70'.

Here's a view from last summer. The first return just is just to the right of the chair.

Here's a view down the plumbing run.

Here's a view where it goes up and over the eave. Note, I hadn't finished painting yet, so the elbow stands out to differentiate from the downspout.

 

[mas985]

What does the suction side look like? Pipe diameters, is there only one suction line? With a single 2" suction line, the pressure levels make sense. The suction side may be limiting the pressure on the return side thereby making the problem worse. In the future, you will probably just need to keep an eye on the filter and make sure the pressure rise doesn't get too high.

 

[dayhiker]

What does the suction side look like? Pipe diameters, is there only one suction line? With a single 2" suction line, the pressure levels make sense. The suction side may be limiting the pressure on the return side thereby making the problem worse. In the future, you will probably just need to keep an eye on the filter and make sure the pressure rise doesn't get too high.

The green handles are the skimmers. They're 2". The red is the main drain, it's a 1.5" I believe.

 

[JohnT]

How hard is it to get to your vacuum breaker? Temporarily replacing it with a cap might answer a lot. More so if you could replace it with a cap with a pressure gauge mounted in it. Knowing that pressure would be very telling. Your filter pressure measures only the pressure between your pump and the outlet of the filter.

Your relatively low filter pressure combined with what appears to be more than adequate suction side flow would seem to indicate that your system has very little restriction between the filter and the pool. That translates into little pressure at the panels. You'll pick up ~7 or 8 psi during the lift, but it drops back down a little more on the downward run since the pool is below the pump, resulting in very little pressure at the panels. Your vacuum breaker could be opening. Or you could have gas coming out of solution during the pressure drop part of the solar path.

Either way, I would have thought that restricting the returns a little would have increased panel pressure, which would have resolve the issues, but apparently it didn't

 

[mas985]

Ok, it still makes sense but now I think that overall you have very low head loss which is good for energy efficiency but can sometime cause problems with solar when the filter gets dirty.

I noticed that you have a ball valve for the solar return. If you continue to have these problems, one thing you could do is to slightly restrict the return on the solar to raise the pressure in the panels and at the VR by a few PSI which should reduce the air getting into the system. Also, when not using solar, there would still be very low head loss.

 

[dayhiker]

I'll reply in one since I think you're both telling me similiar things. What I restricted was the 3 way that feeds the panels. I think you're saying I need to restrict the return which would be where the water coming from the panels ties back into the system. Is that correct?

Also, is low pressure in the panels a problem? Does low pressure mean low velocity which means greater thermal transfer?

vacuum breaker = the valve up on the high end of the panels themselves?


Since we're getting detailed on pumps....is there anything that can be done about my sprayers? I'm drawing a blank on the actual lingo term, but I have a jet in each corner that shoots water up into the air. This is embedded in the slab. They all shoot unequally. The farthest one is just pitiful. My neighbors pool was put in 2 years after mine by the same guy. All 4 of his jets will pretty much meet in the middle. Mine barely get 1/4 of the way into the pool.

 

[mas985]

I'll reply in one since I think you're both telling me similiar things. What I restricted was the 3 way that feeds the panels. I think you're saying I need to restrict the return which would be where the water coming from the panels ties back into the system. Is that correct?
Yes

Also, is low pressure in the panels a problem? Does low pressure mean low velocity which means greater thermal transfer?
Only for the VR. If pressure gets below 0 PSI, it will open. Low pressure could be low velocity but I don't think so in this case. However, low velocity means low heat transfer not greater heat transfer.

vacuum breaker = the valve up on the high end of the panels themselves?
Yes

Since we're getting detailed on pumps....is there anything that can be done about my sprayers? I'm drawing a blank on the actual lingo term, but I have a jet in each corner that shoots water up into the air. This is embedded in the slab. They all shoot unequally. The farthest one is just pitiful. My neighbors pool was put in 2 years after mine by the same guy. All 4 of his jets will pretty much meet in the middle. Mine barely get 1/4 of the way into the pool.

What kind of control do you have for the sprayers? It sounds like the plumber didn't equalize the pressure in the lines. One thing you can do is to change the orfice size to compensate. Reduce the size for those that have a short spray. Check with the manufacture to see if they make other sizes, if not you may to need to do some adjustments yourself.

 

[JohnT]

What I restricted was the 3 way that feeds the panels. I think you're saying I need to restrict the return which would be where the water coming from the panels ties back into the system. Is that correct?

Also, is low pressure in the panels a problem? Does low pressure mean low velocity which means greater thermal transfer?

vacuum breaker = the valve up on the high end of the panels themselves?

Yes. You want to hold water in the panels so the pump can build up some pressure in the panels is a way to think of it. You need pressure in the panels so that the vacuum breaker will seal and stop letting air in. The vacuum breaker opens and lets air in the panels so they can drain, but water pressure closes it when the solar is turned on. You might hear it hissing when the panels drain. It is a "cap-like" object that is usually on the upper header on the same end as the water enters the panels. Low pressure in the panels is good except for the vacuum breaker issue. You could have a bad vacuum breaker. That's what a cap with a pressure gauge would tell you.

Close your return valve a little and see if the bubbles reduce, but watch your filture pressure gauge. The change you see on the filter pressure gauge is the increase in panel pressure you are getting.

Your fountain jets are probably part of the "problem" since they give your water more places to go than just the returns. Smaller return eyeballs or a valve to restrict flow to the returns might help if you can access the return plumbing after the jets split off. The fact that the jets don't have the same flow is either due to your whole return system being so good that there is no pressure to operater them, or more likely a sign that your builder didn't take care to make sure they have equal plumbing paths.

 

[dayhiker]

I'll play with the flow from the panels and see what that gets me.

I do have about the same % of panels as John T, but don't get quite the temp rise. My panels hit shade by 3pm or so, so that's always been my reasoning for why. Could I have a velocity issue that's tag teaming me with the shadow?

Is my "real" issue that the pump isn't quite the right one for this geometry?

On the jets, there is a handle that turns 90° from zero flow to full flow that you manually turn. I don't use them that often due to the noise. They drown out the music. It's all under the slab now, but I can take off teh brass cover plate and have access to the jet itself. It looks like then end of a caulk gun as opposed to a eyeball. I should check my neighbors pump and pressure to see if that explains the difference.

Did I also hear you say that I can adjust the return flow (green handles) to get a jump in pressure in these decorative jets?

I now keep thinking of what-if questions...the red handle on the main drain is very difficult to turn on/off to the point that I'm afraid I'll break it. My installer said to turn it and the off return off when I vacuum. Is this really necessary? I was waiting to experiement when I vacuum it in the near future and just thought I'd ask here since I've turned this into a pump free for all. I have just my solar cover on now and am waiting on these dang oak blooms to finish dropping before I really, really clean it all up. Next year, I'm not doing jack until tax day which is when these awful things stop dropping.

Now if I can just get past the staining issue I mention in the 201 board.

 

[JohnT]

You can play with return flow and see how it affects both the solar and the jets.

Your valves on the suction lines are not very good valves, so I'd imagine your return valve is the same.

 

[dayhiker]

You can play with return flow and see how it affects both the solar and the jets.

Your valves on the suction lines are not very good valves, so I'd imagine your return valve is the same.

The red ones on the solar end of things just feel much more substantial. Is your comment based on the style, or just having run into ones that look like that in the past?

Now that I've plumbed all of that solar, I wouldn't be squeemish about changing those things out. I think I have room to make the cuts.

 

[JohnT]

You can play with return flow and see how it affects both the solar and the jets.

Your valves on the suction lines are not very good valves, so I'd imagine your return valve is the same.

The red ones on the solar end of things just feel much more substantial. Is your comment based on the style, or just having run into ones that look like that in the past?

Now that I've plumbed all of that solar, I wouldn't be squeemish about changing those things out. I think I have room to make the cuts.

They are the low end glue-in ball valves. They tend to be hard to turn, and usually the actual opening in the valve is smaller than the pipe diameter, restricting your flow. Have a look at some of those type valves at a store, and you'll see that the opening through the ball is small. It about has to be, since the valve itself isn't much bigger than the pipe. You'll have to cut your pipe to service your pump since they are glued with no unions in the line. Better valves have union type connections so you can get inside. Best of all are the Jandy type that can be repaired, and that move smoothly for a long time with full pipe ID flow through.

Your whole system looks devoid of unions, but you probably don't winterize, so it's not as big of a deal. It does look like you have some non-pressure fittings in your plumbing. They are the very highest fittings in the picture. From the angle, they look like DWV fittings.

 

[dayhiker]

Those high ones are for the solar. This is all under a stair landing. It's very cramped and I had a hard time getting the geometry to work.

I'll check the valves next time I have the chance. You're correct, all of this stuff is hard connected. I'll look up a union too. I imagine that this is something that lets you disconnect the parts? I thought it strange that it's all hard wired adn the connections are all so tight that you'd have a heck of a time finding a starting and stopping spot to cut.