Solar heating panels introducing air into system

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wayner

wayner

LifeTime Supporter
May 31, 2012
973
Toronto, ON
Pool Size
100000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
I put in a pool in my hose (in Toronto) about 6 years ago. This year I had solar heating panels installed on my roof - these are the evacuated tube type.

The installation has just been recently completed but one thing that I am not sure about is that there is a fair amount of air not introduced into the filter system. You see lots of bubbles pulsing through the water return - not constantly but every couple of seconds or so a burst of bubbles comes through.

The solar panel installer said that this was usual - but I am not too happy about this. I believe that the solar panels have some pressure vents or something where the air is getting in.

I can reduce the bubble by adjusting a valve and reducing the amount of water flow that goes to the solar panels. But will this cause other problems?

The piping to my solar panels was installed just before the heater. There is a valve that when closed diverts all water flow to the panels but when open the water will primarily take the path of least resistance and bypass the solar panels.

Anyone have any advice?
 
Solar panels will always introduce some air into the system each time they turn on. But the air should stop after several minutes, certainly after ten minutes.

If there continues to be air in the system the most likely possibility is that there isn't enough water flow to fully prime the panels and close the vacuum release valve. Try increasing the flow to the panels and see if that improves things.
 
My system has been on for about 8 hours and there is still substantial air coming from the jets. When I close the valve all the way to divert all of the water flow through the solar panels the water flow coming from the return jets is substantially reduced to a wee fraction of the normal flow and the filter pressure goes from 14 psi to 26 psi. Is that normal?

FYI - the piping leading to/from the solar panels is 1" in diameter whereas the rest of the pipes are about 2" in diameter so would it be normal that you couldn't put all of the flow through the panels? My pump is a 1 hp Sta Rite Dynaglass

What's a vacuum breaker valve?
 
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Yes, it is normal that the pressure goes up when sending all the water through the panels. Don't leave it that way for too long, several minutes should be fine. The question is: do the bubbles go away when all water is going to the panels?

A vacuum breaker valve is a small valve that lets air into the pipes when the pressure is low. This allows the panels to drain when not in use. If the pressure at the vacuum breaker valve is too low it will remain open, which could let air in even when the panels are running.
 
Ok, you need to find the vacuum breaker valve and let us know where in the plumbing it is located, it should be on the supply side going to the panels somewhere, or possibly at the highest point on the panels. If it is at the highest point on the panels you may want to move it lower down on the feed side to see if that fixes your problem.

You can do a google image search on solar vacuum breaker valves to see the various styles, most common is a small brass fitting with a black cap about 2 inches across

Ike

p.s. photos might help us spot it
 
OK, here are some photos. It looks like I have two vacuum breaker valves plus one other type of valve. Here is the water flow - it comes from the pool to the panel in the bottom of photo 1 (where the vacuum breaker valve is located. This first panel is on a bit of an incline, it then flows into three panels that lay flat. The output of the last flat lying panel goes up to two more panels that are located higher up and are on more of an incline - these are in the second photo. Initially there were three panels on the higher, steeper incline but the tubes seemed to be pulling away from the manifold. My installer thought that there might be an issue caused by too much pressure of three panels on this incline so he moved the bottom panel over to the flat roof.

Anyone know what that other valve is that goes at a 90 degree angle in the first photo - I show it again in photo 3? Could that be allowing the air to enter?

View attachment 30092
View attachment 30093
View attachment 30095
 
Can you easily crawl around on the roof? I suspect you may be able to hear the hiss sound where air is entering the system. Put your ear next to suspected trouble spots.

My last air entry issue was a bad pvc solder job on one joint, and I was able to hear the air entry at the joint.

You may be able to quickly isolate if it's a vacuum breaker or something else. Do the test with the max flow rate your system can safely handle, to maximize speed (and sound) of air entry.

Also, from a nearby pool owner in Syracuse, N.Y., how well does your tube system work? I opened a little over a month ago with the temperature at about 50F/10c. Today we hit 82f/28c. Solar Attic system. We use a cover.
 
I would guess that the air is entering from the first vacuum valve from what I can hear.

In terms of heating power - the six panels are sized to keep my pool at 84 during the summer. So far I am still also running my gas heater, at least for the weekends. We are still getting unseasonably cool nights in Toronto - often down into the low 50s. But I have shut my heater of for tonight to see what ambient temp it goes to over the next few days - unless I get complaints from the family.

I dont't have a cover.
 

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Well then, if you hear air, that's where to start. :)

For what next in this setup, I defer to the others here who know a bit more about vacuum breakers than I do. Sounds like they already have started down the right path.

Sent from my Nexus 4 using Tapatalk
 
I have no idea what that contraption of valves is for, you might try asking your installer, but neither one looks like a typical vacuum breaker valve. The one pointing to the left may be a foot valve for a well, that is being used as a vacuum breaker valve, they work sort of similar, but I would prefer to have a real vacuum breaker like a Watts N36.

Ike

p.s. to diagnose the problem I would loosen that "foot" valve while the panel is running and make sure you have positive pressure at that point (water comes out), you may have enough siphon effect with that setup that you have negative pressure at the feed point which is something you may need to address.
 
I still haven't gotten around to fixing this issue - is there any problem with having air introduced into the pool? The solar panels are after my pump/filter so the air is only being introduced into my pool.

I have been having one other issue - my SWG doesn't seem to be keeping the chlorine level high enough which is perhaps due to low CYA. I seem to have to keep adding CYA. Would the air bubbles introduced into the pool be an issue with CYA and/or chlorine levels?
 
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