Why does the solar panel boot keep bursting.

knew2pools

Member
Jul 12, 2022
24
Fallbrook, CA
Pool Size
300000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
In the past month I've had to replace the boot on my solar panels 3 times They keep bursting a hole in the same place. Its the boot that connects from the pipe to the first panel. When the solar is running I noticed that boot really expands almost like a balloon so I'm sure that is why it doe eventually bursts. The only change I made to the system was adding a vacuum relief valve end cap. Around the same time the 1st boot burst. So I'm wondering could that cause the problem? Did I install it wrong It;s installed on upper section of the last panel? Do I really need the relief cap? Appreciate any help or thoughts!
 

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That appears to be a connector for a drain system, not designed to be used under pressure. The hose connectors used in solar panel systems are reinforced hose, essentially radiator hose, that can withstand heat and pressure. Take that part to a good auto parts store that may have bulk radiator hose and have them cut a piece to match the inside diameter.
You can get FAFCO connectors at a pool store, most likely, or online.
Its also possible that those galvanized parts have corroded internally and have allowed particles to clog some of the panels, but a true solar connection won't bulge like that.
 
Thank you. I didn't realize there were rubber hoses made specifically for solar panels. I was using the ones from Home Depot. I agree on the galvanized connector it's completely rusting away on the inside. Should I replace it with a 2" Pvc threaded connector?
 
Thank you. I didn't realize there were rubber hoses made specifically for solar panels. I was using the ones from Home Depot. I agree on the galvanized connector it's completely rusting away on the inside. Should I replace it with a 2" Pvc threaded connector?
Something like this is much more secure:
 
In the past month I've had to replace the boot on my solar panels 3 times They keep bursting a hole in the same place. Its the boot that connects from the pipe to the first panel. When the solar is running I noticed that boot really expands almost like a balloon so I'm sure that is why it doe eventually bursts. The only change I made to the system was adding a vacuum relief valve end cap. Around the same time the 1st boot burst. So I'm wondering could that cause the problem? Did I install it wrong It;s installed on upper section of the last panel? Do I really need the relief cap? Appreciate any help or thoughts!
What system pressure is your solar seeing? Are they plumbed for full parallel flow?

A vacuum breaker is a good idea for the system, and should have nothing to do with the issue. Something tells me your panels are set up for cross flow (water flows up one side, down the other) vs full parallel. Can you post a full pic?
 
A vacuum breaker is a good idea for the system, and should have nothing to do with the issue. Something tells me your panels are set up for cross flow (water flows up one side, down the other) vs full parallel. Can you post a full pic?
Here is a full picture. The flow comes into the panels in the lower right in the picture. This is the connection that keeps bursting. The Vacuum relief is on the top left in the picture..
What system pressure is your solar seeing? Are they plumbed for full parallel flow?
I'm not sure the pressure it's seeing I'm running the pump around 2200rpm. PXL_20220826_220448380.MP.jpg
 
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Something like this is much more secure:
Perfect just ordered one. Thank you
 
You've got the return from the panels on the wrong end...so flow through the later panels in the system will not be good, pressure will be higher, and efficiency may be reduced as well. This may have some relevance to your pressure issues. I would swap your vacuum relief and panel return ends. You'll need to add a bit of plumbing up top of your array for the return. Should be like this:

Solar-Pool-Heating-Panel-Systems-are-Z-Type-Heat-Exchangers1-300x180.jpg


You can read more on why you want this here: Flow Rates and Flow Balancing Explained - Florida Solar Design Group

Once you sort that, you should be able to run your pump to get flow to about 45 GPM, a good target for 450 sq/ft of collector (9 collectors, 4'x12' each). Just time a 5 gallon bucket fill at the pool return. I'd also replace those iron bits (they're just adding rust to your system!) with 1.5" PVC fittings (threaded)

435-020__72697.1622467820.jpg


You can replace that fitting with the PVC, or try a shielded coupling like this: Fernco Proflex 1-1/2 in. Neoprene Shielded Coupling P3001-150 - The Home Depot
 
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You've got the return from the panels on the wrong end...so flow through the later panels in the system will not be good, pressure will be higher, and efficiency may be reduced as well. This may have some relevance to your pressure issues. I would swap your vacuum relief and panel return ends. You'll need to add a bit of plumbing up top of your array for the return. Should be like this:

Solar-Pool-Heating-Panel-Systems-are-Z-Type-Heat-Exchangers1-300x180.jpg


You can read more on why you want this here: Flow Rates and Flow Balancing Explained - Florida Solar Design Group

Once you sort that, you should be able to run your pump to get flow to about 45 GPM, a good target for 450 sq/ft of collector (9 collectors, 4'x12' each). Just time a 5 gallon bucket fill at the pool return. I'd also replace those iron bits (they're just adding rust to your system!) with 1.5" PVC fittings (threaded)

435-020__72697.1622467820.jpg

T
Thank You for the great explanation @denwood. I plan to incorporate all your suggestions at the end of the swim year.
 
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Thank You for the great explanation @denwood. I plan to incorporate all your suggestions at the end of the swim year.
@knew2pools , you're quite welcome :) You'll see a pretty big increase in performance (both in flow and BTU) as your first panel is seeing high pressure (and good flow) but GPM would be dropping off per panel to likely near zero on your last panel. While the system is running, take temps on the panels with an infrared temp gun. Your first panel is likely cool (close to pool water temp as it should be), but each down the line will likely be increasingly hot..a sign they are not flowing water efficiently (or at all).
 
It appears that Fernco couplings are gravity drain fittings and are rated for less than 5 psi maximum internal pressure before failing. Might fittings designed for water delivery weight be a better choice for hot water solar?
 
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While the system is running, take temps on the panels with an infrared temp gun. Your first panel is likely cool (close to pool water temp as it should be), but each down the line will likely be increasingly hot..a sign they are not flowing water efficiently (or at all).
Wow!! You're 100% right.. This 1st panel is about pool temp. and each panel afterwards gets hotter. That being the case, I'm going to redesign it now instead of waiting until the winter. Hopefully, that will extend the swim season. Just wondering if I should use 2" pvc for the long return run or keep it at 1.5" the same size I will be tying back into?
 
@knew2pools, I’m pretty sure you will see far better BTU output once you sort the change. If your run is far to the pool, 2” won’t hurt, but the panel plumbing change will make your biggest difference on flow.

Check the temps after and you’ll see they are all about the same. Once flow is fixed, you will see a large difference in heat output on that array :) Try to get 45 GPM at your pool return with the panels in use.
 
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