Noisy 2" Check Valve

[Roguewave]

Huh. My pipes go up the wall at least 20' from my pad, too. They go underground as well. But they both come and go from/to the pad, so I'm not sure what the challenge would be. I'll take your word for it. I'd have to see the whole layout, or a schematic, to better advise. Or, as you say, if it ain't broke, don't fix it.

I like the last sentence there, but...

I guess the challenge wouldn't be immense. Would just have to run some conduit from the breaker panel by the pad... over to the solar corner... then into another outlet. And then buy another expensive cell housing... etc.

I still like that last sentence.

I did some research... which seems to indicate the Hydrogen issue may be more theoretical than demonstrated fact. I'd be interested in hearing some actual reported cases.

 

[Dirk]

I'd be interested in hearing some actual reported cases.

There are none. They were all blown to bits! Kidding (badly).

I know that if solar panels are not installed correctly (bad angles), the panels can trap air and become less efficient. But if they are installed correctly, all the air gets purged when they prime. The same would be true of hydrogen, I expect. So if your panels are OK, I'm guessing there is no H collecting anywhere, and it probably doesn't matter one way or the other about your pump speed (as long as flow is sufficient to force gas down the return side).

Now if hydrogen could collect in a set of panels, like in a corner that is not getting proper circulation, what happens? Will it blow up? Why would it? What would the problem be? I have no idea.

I always assumed it is the highly-chlorinated water coming out of the SWG that is the problem, as the small tubes would be more sensitive to the chlorine than 2" Schedule 40 PVC would be. But I don't have any data on that either. I've learned here that an SWG is always last, just before the pool. That's all I know...

@JamesW, what exactly is the problem/danger with hydrogen collecting in the panels?

 

[JamesW]

Hydrogen is flammable but it needs an oxidizer to burn.

If the hydrogen gas is the only gas, I suspect that the risk is low.

If the chlorine gas also accumulated, the risk would be high, but most of the chlorine dissolves pretty quickly.

If you get a lot of air or other gas accumulated in the panels, the portion that will full of gas will not be effective in transferring the heat to the water.

If the design is good, the air and hydrogen should be removed.

Overall, I would avoid putting the cell before the panels.

 

[Roguewave]

Roger that Dirk & James. Thanks!

My install is pretty straightforward. South facing on a 5/12 comp roof. And it was designed by the top wholesaler in the state... who had been at it almost 3 decades by that time... mostly in southern California.

The panels are 16 years old. The past few years I've had to plug a couple a' leaking tubes or so each season. The climate is 100F in the summer (as high as 108 on occasion) and freezing in the winter. Because of these extremes, tile roofs are known not to last long around here.

I'm no expert, but from what I've been able to gleam, 16 years and counting is pretty good... especially given the climate. No?

 

[JamesW]

The output of an SWG is chlorine gas, which quickly turns to highly-chlorinated water

Assuming 20 gpm and an output of 2 lbs of chlorine gas per day, the FC increase from cell inlet to cell outlet is only 8.3 ppm.

 

[Dirk]

I'm no expert, but from what I've been able to gleam, 16 years and counting is pretty good... especially given the climate. No?

I have 20 years in my head. I'll be happy with anything after that. But I expect I'll be up on the roof patching a few tubes before then. So 16 is getting close. You're probably on track. Anything double digits is pretty amazing, considering the abuse they take, 24/365. I wonder what is worse: the actual heat on the material, or the UV, or the physical stress from the expansion/contraction.

I'm hoping my brand/model will still be around so I can just plug'n'play some new ones into place without having to redo everything. Though I'm not sure the mounting hardware or the PVC supply lines will go a second 20 years. My PVC is supposed to be UV resistant (rated?), whatever that means.

 

[Roguewave]

Assuming 20 gpm and an output of 2 lbs of chlorine gas per day, the FC increase from cell inlet to cell outlet is only 8.3 ppm.

And my single speed pump is rated at somewhere in the neighborhood of 50+. Given my background as the son of a well driller and pump installer, 50+ seems about what my hands are feeling from the total of the 2 main jets and the little one on the side of the Roman steps; at least when the filter is clean.

 

[Dirk]

And my single speed pump is rated at somewhere in the neighborhood of 50+. Given my background as the son of a well driller and pump installer, 50+ seems about what my hands are feeling from the total of the 2 main jets and the little one on the side of the Roman steps; at least when the filter is clean.

Right, but look at it another way. You might be getting 50 through the SWG, but that gets divided across the panels. Say you've got 8 panels. The flow rate through each would be 50÷8 or 6.25 gpm. Then divide by the number of tubes! More to the point, I'm not sure the flow rate even matters. The tubes are being subjected to an extra 8 ppm of chlorine. Does it really matter if the water is moving or not, or how fast? It's still chemical contact. That's just applying my layman's logic, not sure if it actually works like that or not. I also don't know if an extra 8 ppm will degrade a vinyl tube faster or not. If if it does, at what rate? Enough to shave some life off of the tubing? Or its connection to the manifold? Just pondering...

I'm pretty sure the pressure behind 50 GPM is not doing those tubes any favors. You're starting to get leaks. Were they mid-tube? Or where the tube connects to the manifold? As your panels get older, will that kind of pressure start to compromise the connections even more? Then there is the issue of barotrauma during the priming phase. Your panels will be rated for max and working pressure. Maybe a pool pump can't exceed that, but maybe over time it matters? I mean, I run at 40gpm, each panel gets 5. That is the manufacturer's recommended flow rate. So you're not far off (depending on how many panels you have, and they're spec's). I'm just now learning about the barotrauma issue, and haven't figure out how to analyze my setup for that. And like you said, you've gotten 16 years out of yours. If their end of life is 20 years, how will you know if running less GPM, or less chlorine, through them would have gotten you another year? Or five? Or ten? You won't know. Whaddayagonnado?

Sorry, I've only got questions, no answers...

 

[Roguewave]

I have 20 years in my head.

I believe my warranty ran out at 12.

Sorry, I've only got questions, no answers...

Yeah, well thanks for nuthin'.

Just kidding.

Quite a bit to unpack there. I won't give you the flow rate through the individual tubes argument. That's relative. Just think of it as velocity. And everything is divided between the complete set of tubes from all of the panels.

However, I WILL give you the division among panels point. Yes. I have 9 panels. So 5.6 GPM if given a total of 50.

BUT... you were on to something about the chemical contact. JamesW specifically pointed to chlorine increase at a rate of 20 GPM... of 8.3 ppm after the cell. Yes, this is a measurement of proportion. And since my rate after the cell is about 2.5 times the figure he offered, my increase would be more in the range of 3.3 (8.3 / 2.5.) Since the 3.3 is a proportion, the division of flow among the 9 panels has no bearing. In this example, there is simply an average of 3.3 additional ppm residing within those panels over the course of a given day. Hardly a heavy bleaching.

That said... the 3.3 will be in addition to what's already in the pool... which... given a CYA of, let's say... 80... should be around 6 per Pool Math. BUT... because of the CYA... the chlorine is not as active, right? It's probably more in line with 2 ppm or so if there were no stabilizer, as a guess. So let's just call it 5.5 ppm average total... within the panels... from morning to evening. I can't imagine that's enough to do much, if any damage.

All of the leaks have been somewhere in the middle. None at the manifolds.

I just checked again and verified... my panels came with a 12 year, full warranty. But the wholesaler states they could last twice that with a perfect installation in perfect conditions. Given the climate, I would be happy with 20. And it doesn't appear the SWG has been much if any detriment.

 

[Dirk]

Were the holes in the tubes on the top or the bottom? When I installed my panels, I took great care to make sure the tubes aren't touching anything. Mine came with spacers that hold each tube off the roof, and I had to move them (total pain!) to get them to align correctly with the roofing tiles. But I was (am) convinced that the constant, daily movement of the tubes over the roofing material, due to the entire array expanding and contracting, would be like sawing each tube with a rasp, was it not for these spacers. Have you seen any evidence of that kind of wear?

PS. I expect 5.6 gpm per panel would be well within spec and just about perfect for heating efficiency. Did you ever ascertain what the manufacturer recommends for flow rate? That's where I got my 5 gpm per panel for my setup.

PPS. Assuming your math regarding the "chemical contact" is right, yah, it seems farfetched that the additional chlorine would amount to much.

 

[Roguewave]

That's a really good question. No. All holes have been on the top. For some reason this never occurred to me. And they're laying right over the sandy comp roof. AND... when making repairs and such... my big, heavy body has no choice but to sit on the panels. I've often wondered if this season's repair isn't causing next season's hole. And what a pain it would be to find which tube to repair if the hole was on the underside.

But isn't that interesting? Seems to give weight to the temperature extremes idea. The roof would be a hair warmer than the air in the winter. And obviously the panels get hot on the top in the summer when the thermostat is not calling for heat. AND they're getting a UV workout all summer on the top only. And it's basically blue skies in this region for 3 months on end all summer. That said... with conduction... I imagine both the tops and bottoms would run about the same temp. So I would guess UV is likely the biggest factor in the holy tops.

I have not ascertained ideal flow rate for heating efficiency, but... I imagine there is a minimum... and not a maximum. The more flow, the cooler the panels and the greater the capture and redistribution of energy, right?

 

[Dirk]

I have not ascertained ideal flow rate for heating efficiency, but... I imagine there is a minimum... and not a maximum. The more flow, the cooler the panels and the greater the capture and redistribution of energy, right?

Correct. The limiting factors are pressure (how much the tubes and connections can take), and the energy cost of the pumping.

So I would guess UV is likely the biggest factor in the holy tops.

Huh, I wonder if it would be smart to flip my panels over at about 10 years! I'd have to reset all those stupid spacers, but would it be worth it to swap the UV exposure?

 

[Roguewave]

Correct. The limiting factors are pressure (how much the tubes and connections can take), and the energy cost of the pumping.


Huh, I wonder if it would be smart to flip my panels over at about 10 years! I'd have to reset all those stupid spacers, but would it be worth it to swap the UV exposure?

Energy is cheap in Oregon. And solar is my only heater. My priority is the most pool enjoyment possible.

The primary benefit of a 2 speed pump up here is to keep things moving during freezes at a lower cost

And... perhaps. Sure sounds like a royal PITA, though.

For mine... I kind of wonder if I shouldn't leave well enough alone at this point.... given that all of my holes seem to be on the tops. And there haven't been that many.

Plus... time is money. I'm self-employed. My time is better spent working.

 

[i30swimmer]

A Jandy check valve is what I'd recommend. Or better yet, a FlowVis flow meter (which doubles as a check valve). If you have a variable speed pump, you can fine-tune your solar heating system by adjusting your RPMs to achieve the perfect flow rate for your panels (using the flow meter). The FlowVis is based on a Jandy check valve body, and the FlowVis is sold with and without the body. So you could install a Jandy check valve now, and later upgrade it to a FlowVis if you decide to. Optimizing your flow rate will get the most heat in your pool for the least amount of cost (electricity). Theoretically, a FlowVis will pay for itself. It might take a hundred years, but, hey, it'll get there!

The check valve you're using now looks to be of low quality and if you're having trouble with it now, I'd guess it's only gonna get worse. Jandy check valves have a clear housing (as does the FlowVis) so you can visually inspect them at anytime, without taking them apart. Either is the right tool for the job, IMO.

I picked up a FlowVis flow meter as I get ready to redo my plumbing and install new filter and VS pump. After it arrived, I was manually manipulating the flowvis check valve and it seems like it will be very restrictive on water flow. Should I be concerned about this flow restriction? Sorry for reviving an old thread.

 

[1poolman1]

I picked up a FlowVis flow meter as I get ready to redo my plumbing and install new filter and VS pump. After it arrived, I was manually manipulating the flowvis check valve and it seems like it will be very restrictive on water flow. Should I be concerned about this flow restriction? Sorry for reviving an old thread.

No