Please help identify air-intake (solar related)

Sandy Pool

Active member
Dec 17, 2015
42
Orlando, FL
Central FL, 10K gal, in-ground, 1.5hp

Pool -> pump -> filter -> jbfv1 -> solar up -> solar down -> jbfv2 -> chlorinator -> pool
(jbf= jandy back flow valve with window)
(chlorinator is for 3" tabs, inline but empty & functionally off)

I just turned the solar on today and immediately see and hear lots of bubbles on the return side. The condition was not present when I turned the solar off last fall. It acts like there is air intrusion on the suction side. However, the pump see-through basket shows no air and the window on the Jandy back-flow valve #1, before the pipes go to the roof, shows no air. The back flow valve #2, after the roof, shows lots of air visible.

This totally confuses me. I don't understand how air can be sucked into the piping on the roof, which is on the pressure side of the pump. FWIW, there is no visible leakage of water from the roof (or anywhere else in the system).

Obviously, I don't understand something fundamental because I would have thought the symptoms I'm describing would have been impossible. I would greatly appreciate any enlightenment (or even informed guesses!). Thank you.
 

chiefwej

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Jun 12, 2011
3,306
Tucson
When the system is shut down there is a relief valve on the roof that allows air into the panels. That allows the water to drain, to prevent the vacuum created from damaging the panels. So each time the solar is started up that relief valve closes, and it is normal for all the air in the solar panels to come bubbling out of your pool returns.
 

Sandy Pool

Active member
Dec 17, 2015
42
Orlando, FL
When the system is shut down there is a relief valve on the roof that allows air into the panels. That allows the water to drain, to prevent the vacuum created from damaging the panels. So each time the solar is started up that relief valve closes, and it is normal for all the air in the solar panels to come bubbling out of your pool returns.
Thank you. By "starting up", do you mean the seasonal startup would be different than the daily routine?

I believe that relief valve has functioned the way you describe each time (usually at pump shutoff time each evening) the pump cycles off. And I do recall seeing air upon the daily startup, but usually just a few seconds worth; the new air problem has been going for a few hours.

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pooldv

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Aug 10, 2012
25,172
FL panhandle
The solar panels should drain every time solar shuts off. And they should blow out quite a bit of air each time solar starts up again.

Blowing air for hours is too much and indicates there is a leak somewhere. A couple of springs I had to go tighten up some of the hose clamps between the panels.
 

Sandy Pool

Active member
Dec 17, 2015
42
Orlando, FL
Blowing air for hours is too much and indicates there is a leak somewhere. A couple of springs I had to go tighten up some of the hose clamps between the panels.
Trying to understand... if there's a leak on the roof, which is the pressure side of the pump, wouldn't I see water leaking on the roof?

One more FYI data point: I don't think this is likely relevant because I ran the system for several weeks with no issues, but late last season I had a leak (squirrels) that was repaired. At the same time, the tech moved the vacuum relief valve from a position from below the roof line to up high - I believe to the highest point.

Thanks for everyone's time and help!



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JamesW

TFP Expert
Mar 2, 2011
13,334
The change in vacuum relief valve height is the likely cause. The higher it is, the more flow you need to keep it closed.
 

pooldv

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Not if it is more on the downhill end, it can create more of a suction type leak as gravity pulls the water back down. There has to be an air leak somewhere for the bubbles to be in the returns. I assume there are no bubbles when solar is off.
 

Sandy Pool

Active member
Dec 17, 2015
42
Orlando, FL
Is the following a plausible theory?

Reference: If I choke off the supply of water to the pump, air shows itself as the pump tries to draw more water than is available. I refer to this as "cavitation" although I may well be using the wrong term.

Applying that observation to my solar air ingression problem (and for the sake of argument assume there is not a leak in the roof piping), is it possible that a blockage would interfere in the flow of water downhill and cause "cavitation", resulting in the bubbles?
 

pooldv

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No, in order for air to come out of the pool returns it has to get sucked into the plumbing somewhere. And nothing should get past your filter that could clog up anything anyway. Cutting off the water supply to a pump does cause cavitation, but it has nothing to do with air in the plumbing.
 

JamesW

TFP Expert
Mar 2, 2011
13,334
The air is probably getting sucked in at the vacuum relief valve. To solve it, you’re probably going to need to increase flow, lower the vacuum relief valve or create a restriction on the return side of the solar.
 

pooldv

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If the VRV is at the end of the upper header you could move it down to the lower header.
 

Pool Clown

In The Industry
Sep 5, 2008
1,853
Silicon Valley, CA
You should be getting air purging from the panels not only when the pump comes on (if there is enough sun on the panels), but every time the solar cycles.

I would be willing to bet that the drain down valve is in the right spot. If the air never quite works its way out, there are three ways air could be getting in at the solar panels. As stated above, it can be a loose panel connection (via a venturi effect), if you have a variable speed pump, the speed may be a bit low, and not enough flow to keep the drain down valve closed. Or lastly, a stuck(open) drain down valve.

If you have a Jandy type check valve at the outlet, or somewhere between the filter outlet and the solar diverter valve you would be able to see if there is a any air exiting the filter. This would tell you if it is coming from the pump/filter or the solar.
 

Sandy Pool

Active member
Dec 17, 2015
42
Orlando, FL
I would be willing to bet that the drain down valve is in the right spot. If the air never quite works its way out, there are three ways air could be getting in at the solar panels. As stated above, it can be a loose panel connection (via a venturi effect), if you have a variable speed pump, the speed may be a bit low, and not enough flow to keep the drain down valve closed. Or lastly, a stuck(open) drain down valve.
The pump is an old 1-speed, so that should be a constant. Related, I did have a dirty filter that was considerably reducing flow, but I corrected that before this solar-related problem appeared. All my tests and observations here have been with pump/filter operation that is similar to what has always worked in the past. The stuck open valve is a definite possibility - any way to verify, short of going on the roof which I can't do?

If you have a Jandy type check valve at the outlet, or somewhere between the filter outlet and the solar diverter valve you would be able to see if there is a any air exiting the filter. This would tell you if it is coming from the pump/filter or the solar.
I do have Jandy check valves with windows and I can clearly see water from the filter, going up, to the solar is bubble-free and water, coming down, from the solar is full of bubbles.

Now, a couple of new observations that seem significant to me:

1) I have always been aware of a loud fog horn type of sound from the valve when the solar (or pump) turns off. I no longer hear this. Might that indicate a stuck open valve? Or stuck closed? Or indeterminate?

2) I see partly crushed top header pipes. Visual inspection is difficult and I'm not sure but... there is a pipe, approximately 3", that goes between two banks of panels, perhaps a distance of 6 feet. This is at the top of the panels and is at the point where it collects the hot water going up the actual panels and is the last pipe before sending the heated water down to the pool. The "crush" looks to be about 50% of the original pipe diameter. I've read that one reason for the vacuum relief valve is to prevent negative pressure from unvented pipes that could crush said pipes. Is that likely here? Would that rule out a stuck-open valve in favor of a stuck-closed valve?

Thanks for everyone's help!
 

pooldv

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Your theories are sound and certainly possible. My solar panels sometimes make the foghorn-ish sound when draining but it isn't consistent and hasn't prepared to cause a prpblem. So, I haven't paid enough attention to try to dertmine what factors may contribute to it making the noise. First thing I would do is install a new VRV valve. If that doesn't fix it then I would move it. Where is the VRV now, top header? Is the crushed hose a rubber connection hose?
 

Sandy Pool

Active member
Dec 17, 2015
42
Orlando, FL
Hi. I can't really get to the VRV, so if that's it, then I need to call for service. I'm trying to diagnose it so if it's something I can reach and fix, I'd do it myself; if not then I can at least be confident that my service money is well-spent.

The VRV is at the very top/end of the panels. A little hard to describe, but the water flows from bottom-to-top and the VRV is at the furthest top corner.

The apparently-crushed pipes are rigid (based on what I can see elsewhere, probably Sched 40).


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mas985

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May 3, 2007
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Pleasanton, CA
Is the filter pressure normal for a clean filter? Not too high or too low from last year?

Too low and it could be an impeller or line clog.

Too high and it could be a filter issue or the crushed pipe.
 

Sandy Pool

Active member
Dec 17, 2015
42
Orlando, FL
Filter pressure seems a little low (6psi) but that could just be a cheap ebay gauge. It doesn't change appreciably when the solar turns on.

My waterfall has always been a pretty good, though admittedly subjective, indicator of a dirty filter. I can tell from the flow that something - typically the filter - is impeding good circulation. It's good.

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