Solar Heater Addition in Baton Rouge, LA (DIY)

[Matchless1]

Well, I decided to go ahead and install a solar heater for my pool, which I just completed last July. I'm doing it myself with help from my dad. I'll be using 2 banks of 7 panels 4' x 8' each (they couldn't make 4' x 16' panels unfortunately) from Techno-Solis. I'll be running 2" pipe all the way.

Here are my plans:





Panels will be placed on the middle section of the roof over the patio. Equipment/pump is on the left side of the house in this view:



We were able to get all of the bottom piping done this past weekend (still need to add actuators to both valves though), and my pool builder hooked me up with an amazing price on some 20' sticks of 2" pipe. Here are some progress pics so far:




















While I'm waiting for the panels to come in, I did have a few questions for the forum:

1. Is there a chance I’ll get less flow to the top bank of panels vs. the bottom bank? Should I install flow meters before each one with a diverter valve?

2. The panel manufacturer recommends sloping the panels 1/4" per foot back towards the supply/inlet of the panels to allow draining for freeze protection. But if I choose not to slope the panels (controller will circulate water during freeze temps), and I have a vacuum breaker on each bank of panels, won’t the water still drain to the lowest point (the pool) should I ever need to drain the panels for maintenance reasons?

3. Excluding freezing conditions, I’ve heard that while the panels are not operating it is better to leave them full of water instead of having them drain. Is that true?

 

[jblizzle]

1. Yes the upper will likely have slightly lower flow depends on how you plumb it.

2. The slope is more so the air is all removed when the solar starts up otherwise it could get trapped and not all the panel will have water flow.

3. Wrong. The water would get extremely hot and would end up causing "negative pressure" and weaken the tubes and possibly damage them.

Why do you need 2 actuators?

 

[Matchless1]

1. Yes the upper will likely have slightly lower flow depends on how you plumb it.

Ok. So based on that, I'm considering changing the cross (top right in the photo below...ignore the white lines in the middle...that's my house wall underneath the roof) to a tee and moving it halfway between the two inlets. However, I think doing that would not allow the water to drain properly from the bottom panels (top panels in photo below) when not in use, right?

And along those lines, is it necessary to slope the piping from the panel inlet all the way back to the pump? I wouldn't think so, since I don't need the pipes to be COMPLETELY empty, but what have others done? It's quite a long run, so sloping (even at 1/8" per foot) would mean a very considerable drop from pump to panel inlet.

2. The slope is more so the air is all removed when the solar starts up otherwise it could get trapped and not all the panel will have water flow.

That kind of makes sense, but how does the air escape if there is no high point vent (just a vacuum breaker)?

3. Wrong. The water would get extremely hot and would end up causing "negative pressure" and weaken the tubes and possibly damage them.

Negative pressure? Wouldn't the increase in temperature cause a positive pressure? Also, even if a negative pressure was induced after cooling back down (i.e. at night), wouldn't the vacuum breaker take care of that?

Why do you need 2 actuators?

I wasn't going to use 2 auto valves, but my Pentair automation technician recommended adding a 2-way ball valve between the check valve and the tee to the left of the 3-way valve. He said it would help seal better, since check valves allow a little bit of leakage...so sort of a double isolation (eh, ok). But mainly, he said it would help keep the water from draining out of the panels (past the check valve) when not in use. He was one of the ones that said I should leave the panels full of water when not in use.

But if leaving the water in the panels is really going to be a problem, I would probably just leave the 2-way valve open at all times to allow the return line to drain (turning the pump off for a few minutes after sending water to panels and before bypassing straight to the pool). I would also need to change out the diverter in the 3-way valve to the one with the drain hole in it. I already have one, but replaced it with a standard diverter because it does allow some water to pass through even when "closed", which doesn't work so well with open ended pipes at the moment.

 

[pooldv]

Air is pushed out through the plumbing when solar turns on. It works better when the air isn't able to collect in areas that are slightly higher than the plumbing exit.

+1 that the panels needed to be drained when not in use. This is accomplished by using a solar 3 way valve which has a small hole and a flapper. There are pics of solar plumbing in my pool thread. One 3 way valve is all that is required. The left pipe goes up and the right is the return.

 

[Matchless1]

Air is pushed out through the plumbing when solar turns on. It works better when the air isn't able to collect in areas that are slightly higher than the plumbing exit.

+1 that the panels needed to be drained when not in use. This is accomplished by using a solar 3 way valve which has a small hole and a flapper. There are pics of solar plumbing in my pool thread. One 3 way valve is all that is required. The left pipe goes up and the right is the return.

I just talked to the manufacturer of the panels again and asked him some of these questions. The bottom line is as long as I plan to circulate the water during freezing temps (which is rare down here and my controller already does), there is no other reason to drain the panels after each use. If maintenance is needed, I can drain them to my gutters (then to the ground) with the drain valve by the panel inlet on the cross. Sloping the panels left to right will help drain more water out of the bottom pipe(s), but it is not necessary to drain the panels. Why? Because the panels are on a sloped rough to begin with.

Regarding different flow between the top and bottom banks, they said at first that's possible, but after the system gets steady, the flow should be about the same. No need to move the tee up in between the two inlets.

Regarding air in the line, that is the main reason I don't want to drain the panels after each use. Sloped panels or not, vacuum breaker or not (unless it's really also a positive pressure relief valve), draining the panels will leave lots of air in the pipes that will need to be pushed out every time I send water to them. This means bringing the pump up to speed very gradually to avoid water hammer and slug flow, which has been known to bust joints, especially at 90 degree turns. I don't mind baby sitting a slow startup the first time and here and there, but I don't want to be worried about clearing air out of lines every time it switches on, which I intend to have happen automatically using the temperature sensors.

I'm familiar with the 3 way valve with the hole in the flapper. I tried it out at first, but guess what...it drains like it should, but (BONUS) it also leaks past the flapper in the closed position when it shouldn't. That's hardly a "valve" in my book. More like a flow inhibitor, which ultimately will lead to the panels filling back up over the course of a 9-10 hour summer pump cycle.

So, I think I'm back to my original plan (as shown above), which is using the actuator on the 2-way and 3-way valve (w/o the hole in the flapper) and leaving the cross and drain valve where they are (near the inlet of the first panel). I may still slope the panels very slightly (~1/16" per foot) just to drain the bottom pipe a little better, but maybe not.

 

[jblizzle]

My solar drains every day. Pump fires up at high speed. Never had a problem with hammer or plumbing.

Leaving water in the panels in the sun without flow is a bad idea. And having to pump the air out daily is no big deal.

 

[Isaac-1]

Ok, just my few thoughts:

1 slope the panels, this will prevent air getting trapped in them and causing uneven flow, it will also allow them to drain better during a potential freeze, sure freeze recirculation is good, but I prefer a belt and suspenders approach. I live in western Louisiana, roughly due west of St Fancisville so know the climate and how often we get hard freezes, etc. with a sloped panels a proper solar valve that drains or a bypass bridge and a vacuum breaker valve then you have a backup in case the freeze recirculation fails. 2 common failure modes here are a temperature sensor going bad or a power failure during an ice storm. I know ice storms are a once in every 25 year event for Baton Rouge, but why role the dice.

2, plastic Solar panels should be self draining so water is not left in the tubes, period see ( you can find a lot of good information at Powerstrip Solar Pool Heaters from Hot Sun Industries of San Diego, California specifically see Hot Sun Industries Case Study Rigid Solar Pool Heating Panel Issues with Pressure and Variable Speed Pumps sure there is some marketing slant towards their product, but still lots of good general info)

3, I assume you have an automation system to control the solar panels valves? If not get one, timers and solar do not work well in our climate where we are prone to get afternoon thermal thunderstorms that suck so much heat out of running panels.

 

[Matchless1]

Ok, just my few thoughts:

1 slope the panels, this will prevent air getting trapped in them and causing uneven flow, it will also allow them to drain better during a potential freeze, sure freeze recirculation is good, but I prefer a belt and suspenders approach. I live in western Louisiana, roughly due west of St Fancisville so know the climate and how often we get hard freezes, etc. with a sloped panels a proper solar valve that drains or a bypass bridge and a vacuum breaker valve then you have a backup in case the freeze recirculation fails. 2 common failure modes here are a temperature sensor going bad or a power failure during an ice storm. I know ice storms are a once in every 25 year event for Baton Rouge, but why role the dice.

2, plastic Solar panels should be self draining so water is not left in the tubes, period see ( you can find a lot of good information at Powerstrip Solar Pool Heaters from Hot Sun Industries of San Diego, California specifically see Hot Sun Industries Case Study Rigid Solar Pool Heating Panel Issues with Pressure and Variable Speed Pumps sure there is some marketing slant towards their product, but still lots of good general info)

3, I assume you have an automation system to control the solar panels valves? If not get one, timers and solar do not work well in our climate where we are prone to get afternoon thermal thunderstorms that suck so much heat out of running panels.

Again, I don't see how sloping the panels prevents air from getting in them, especially if I were to drain them after each use, which everyone seems to do. All sloping them would do for air is move the air to one corner instead of distributed across the top. I'll probably still slope them anyway, like I said, if for no other reason than to empty the bottom headers of the panels more completely. Also, I do like the idea of having an alternate freeze protection option for the reasons you mentioned.

Thanks for the links! Very interesting about max recommended pressure being around 8 psig. I had not heard that yet, nor does the Tecno Solis literature mention that (at least that I could find). I'll definitely be adding a pressure gauge near the panel inlet now. Here's an excerpt from the 2nd link I found interesting:

The second question is ,”Why is solar seeing the pressure in cleaning mode?” Solar is off and fully isolated at this time by the return line check valve and the positive sealing motorized valve. The only way solar sees that pressure is if the check valve or the positive sealing motorized valve leaks. We didn’t install this system. There is a common motorized valve used by many in the solar business. Its supplied by the big manufacturers and its called a solar valve. This is a regular 3 way valve with a small check valve built right into the spool. The idea is that when solar is off water can drain down through this internal check valve emptying the plumbing and solar panels. You don’t want water in the solar panels when it freezes in the case of rigid panels because they will freeze and burst and warranties don’t cover that. They don’t cover that stupid little internal check valve seizing up either by the way. Obviously (obvious to you if you’re understanding all this pressure talk) that internal check valve isn’t going to let any water out of any solar panel if the solar panel is below pool level or if the system pressure (in feet of head) is higher than the height of the solar panel. We don’t bother with the “solar valves”. We use regular pool industry standard valves. They seal 100%. Maybe this is a solar valve and maybe the SLCV (stupid little internal check valve) is leaking. That would be ironic. The solar specialty valve is the cause of the solar specialty failure to the tune of 45 solar panels! Maybe the seals just failed. Maybe the installer removed the seals on purpose? Maybe it’s the check valve on the return line that is leaking. Maybe solar was on when the pump was on the higher speed. If the SWIM PC was the solar controller we’d know that but we think its pretty safe to say solar wasn’t on. We see this same pattern for the 5 days we logged data and this is mid winter and the days weren’t all sunny days.

This is exactly why I don't understand the Pentair "Solar" 3-way valve. The little check valve inside the diverter doesn't completely seal in the "off" position. What good is that? For those of you using this valve, have you actually checked to ensure your panels are not actually filling up when this valve is "closed"? The next question though is...if I use a standard 3-way valve (which I currently have installed), how do I drain the line from the pump to the panels? My actuator rotates 180 degrees and there is no option for a 3rd position where both sides of the valve are open (which is what I would need to allow it to drain back to the pool).

Yes, as my sig states, I have a Pentair Intellitouch i5+3S w/ Screenlogic 2.

 

[jblizzle]

I have the solar 3 way. In the off position, I know the water does not make it to my roof all winter while the drain valve is open. And before I installed the panels, the water never came out an open pipe that was about 4 feet above water level.

Even with that, I added a cross over on the pipes going to the roof that helps the supply side drain

 

[Matchless1]

I have the solar 3 way. In the off position, I know the water does not make it to my roof all winter while the drain valve is open. And before I installed the panels, the water never came out an open pipe that was about 4 feet above water level.

Interesting. What kind of solar 3 way valve do you have? Is it the Pentair one? If so, I guess mine is just broken.

Even with that, I added a cross over on the pipes going to the roof that helps the supply side drain

Do you have a picture of the cross over you installed?

 

[pooldv]

I also have no issues with my Pentair 3 way solar valve. There is a pic of my crossover in the link in my sig, left pipe goes up to solar right pipe returns.

Mine have been installed about 4 years. These are the install instructions I used, solardirect.com vortex-install-manual.pdf

 

[Matchless1]

Alright, well I must have a faulty 3-way valve then. I actually took it apart today to see exactly how it works. The little check valve seems to be moving like it should. So, I put the diverter back in the 3-way body to test it again. What I found was that at higher speeds (3110 rpm) it performs like it should...no leaks. But at lower speeds (1700 rpm), which is where I normally run it, it leaks like a sieve. This actually makes sense though...higher speeds push the check against the seat better creating a tighter seal. Lower speeds allow the check to "float" slightly, thus allowing water to flow past easier. Here's a video I took, showing exactly that: 3 Way Valve Leaking - YouTube

Are you guys just running your pumps at higher speeds?

FYI...It takes about 30 minutes to fill 5 feet of 2" pipe at 1700 rpm. With the length of plumbing I have, doing the math shows it would take 5.5 hours to fill all the pipe up to the first panel (~55 feet). Then another 3 hours to fill the bottom header of the first panels (~30 feet). So on a 9 hour cycle (longest during the summer), the bottom of the panels would start to fill up a little bit before the cycle finished.

 

[pooldv]

I'm running at 1100 rpm on standby. So maybe not enough pressure to push past and leak up.

 

[xyz]

Alright, well I must have a faulty 3-way valve then. I actually took it apart today to see exactly how it works. The little check valve seems to be moving like it should. So, I put the diverter back in the 3-way body to test it again. What I found was that at higher speeds (3110 rpm) it performs like it should...no leaks. But at lower speeds (1700 rpm), which is where I normally run it, it leaks like a sieve. This actually makes sense though...higher speeds push the check against the seat better creating a tighter seal. Lower speeds allow the check to "float" slightly, thus allowing water to flow past easier. Here's a video I took, showing exactly that: 3 Way Valve Leaking - YouTube

Are you guys just running your pumps at higher speeds?

FYI...It takes about 30 minutes to fill 5 feet of 2" pipe at 1700 rpm. With the length of plumbing I have, doing the math shows it would take 5.5 hours to fill all the pipe up to the first panel (~55 feet). Then another 3 hours to fill the bottom header of the first panels (~30 feet). So on a 9 hour cycle (longest during the summer), the bottom of the panels would start to fill up a little bit before the cycle finished.

Something I amiss here. In minutes, I pump hundreds of gallons of water through my array [~8' y 60'].

My guess here may be that you are not generating enough pressure to get the water to flow. OR, you may have a bad or warn impeller that is limiting your pump performance.

For example at 1200 RPM, I get ~50GPM through my filter. However at 1200 RPM I get zero GPM out of my array, because the pump won't generate enough head pressure to get the water up to the roof. Could this be it?

 

[jblizzle]

Alright, well I must have a faulty 3-way valve then. I actually took it apart today to see exactly how it works. The little check valve seems to be moving like it should. So, I put the diverter back in the 3-way body to test it again. What I found was that at higher speeds (3110 rpm) it performs like it should...no leaks. But at lower speeds (1700 rpm), which is where I normally run it, it leaks like a sieve. This actually makes sense though...higher speeds push the check against the seat better creating a tighter seal. Lower speeds allow the check to "float" slightly, thus allowing water to flow past easier. Here's a video I took, showing exactly that: 3 Way Valve Leaking - YouTube

Are you guys just running your pumps at higher speeds?

FYI...It takes about 30 minutes to fill 5 feet of 2" pipe at 1700 rpm. With the length of plumbing I have, doing the math shows it would take 5.5 hours to fill all the pipe up to the first panel (~55 feet). Then another 3 hours to fill the bottom header of the first panels (~30 feet). So on a 9 hour cycle (longest during the summer), the bottom of the panels would start to fill up a little bit before the cycle finished.

Mine is Pentair.

I think this ignores the extra head of raising the water up so it may take even longer to fill up to the panels of ever.

Could be that I only checked on high speed, but even running on low, water still never reached the roof.

 

[jblizzle]

Something I amiss here. In minutes, I pump hundreds of gallons of water through my array [~8' y 60'].

My guess here may be that you are not generating enough pressure to get the water to flow. OR, you may have a bad or warn impeller that is limiting your pump performance.

For example at 1200 RPM, I get ~50GPM through my filter. However at 1200 RPM I get zero GPM out of my array, because the pump won't generate enough head pressure to get the water up to the roof. Could this be it?

You are missing the point of this discussion we are talking about the flow that is bypassing a check valve in a 3 way solar valve.

 

[xyz]

You are missing the point of this discussion we are talking about the flow that is bypassing a check valve in a 3 way solar valve.

Why would he want to fill his 55' array with the valve closed?

 

[pooldv]

He doesn't, that is why we are discussing it.

 

[xyz]

He doesn't, that is why we are discussing it.

Ah, thanks.

 

[Matchless1]

Mine is Pentair.

I think this ignores the extra head of raising the water up so it may take even longer to fill up to the panels of ever.

Could be that I only checked on high speed, but even running on low, water still never reached the roof.

Good point. I emailed Pentair explaining the issue. Hopefully they can offer a solution. I may just have to live with the solar piping filling up (to some extent) during the day then draining down at night if they can't offer a fix.

Curiously, how did you check whether or not the valve was leaking past (since the pipe is not clear)?