Solar plumbing question for ground mount solar system?

Booshy

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Nov 24, 2020
4
Poway CA
solar plumbing.JPG

I am looking for the best way to plumb my new pool solar system. I am connecting to an existing pool plumbing system that is working.

I am running two heaters and one Variable speed pump (Pentiar Intelliflo VSF).

The pool has a total of 6 Pumps running several other features.

The pool is controlled by a Pentair Easy touch Control System. I believe I am using all 8 buttons.

I would like to connect in the panels and want to make sure I am doing It correctly and the most efficient way?

Here are my questions?

Is this plumbed correctly?

Should I install check valves going to and coming from the solar panels?

Do I need to worry about water returning from the solar panels and flowing backwards into the heaters? Per my drawing?

Will the Easy Touch control system control my solar and new 3 way valve? I see it has a solar button but I would like to set the pool to a specific temperature and have it open and close the valve to the solar as needed?


Thanks you for your thoughts and input its appreciated.
 
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ajw22

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Welcome to TFP.

You will get a better response if you post your text in the message where it is readable by the many different types of devices used then in a picture. If you make it difficult for folks to understand your problem and reply many will bypass the thread.
 

Booshy

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Nov 24, 2020
4
Poway CA
Welcome to TFP.

You will get a better response if you post your text in the message where it is readable by the many different types of devices used then in a picture. If you make it difficult for folks to understand your problem and reply many will bypass the thread.


Thank you. I just updated it. Hope this helps..
 

ajw22

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@Dirk solar in CA seems up your alley.
 

Dirk

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Hmm, I'll start with the easy answers...

Yes, the ET will control that 3-way to turn on and off the solar heater. You'll need to install an actuator on the three-way, and two temp sensors. One near the panels (which measures the heat of the air/sun on the panels) and another in the plumbing, which measures the temperature of the pool water. You would install the air sensor right next to one of the panels. The water sensor would go in between the pump and the solar valve. The ET comes with the required sensors, so maybe you already have those.

You need a check valve on the pipe returning from the panels. That keeps water from flowing into the panels when the three-way valve is in the solar-off position. In your case, that would be doing its job whether the filter pump was on or off, because your panels are below the pool. You don't need the check valve on the supply side of the panels, the three-way valve serves that purpose. You want water flowing toward the panels when the system is heating, and the three-way will prevent flow in either direction in its solar-off position.

You didn't plot where your filter is. Typically there is a check valve between the filter and the solar three-way, which keeps "solar panel water" from back-flowing into the filter. That's seen in systems where the panels are above the pool. We'll come back to that. The panels should be after the the filter, so only filtered water goes into them.

Regarding back-flowing into the heaters: typically the return from the panels comes back into the pipe that leads into the heaters, not the way you have it. That would solve the back-flow issue. It would also allow the gas heaters to heat the solar-heated water. That would be more efficient, and get you to a desired temp quicker if you were heating up the spa during sunlight hours.

Now the kicker is, I don't have any experience, nor have I read or studied how to plumb panels that are below the pool. The inherent problem is that the panels should be able to drain after the heating session is done. You don't want water sitting in the panels overnight, because the first thing you'll do the next day is pump a bunch of cold water into your pool. This is especially important if temps get to freezing at night where you live, because the expanded frozen water could destroy the panels.

Typically, the solar valve is not a normal three-way. You use a "solar drain-down" three-way, which allows water from the panels to drain down into the pool once the filter pump shuts down for the day. And there is a vacuum-relief valve installed to allow air into the panels so they can drain properly. But... I have no idea how to accomplish that when the panels are below the pool surface. I suppose you could leave the water in the panels for most of the days of the year, and then drain them before winter. You'd install a hose bib or two in the panel plumbing for that purpose. But that would be a manual task. You'd be wasting all that water if you did that daily during the colder months. Not too bad if done just once a year. If it never gets that cold down south where you are, maybe this is a non issue.

If you schedule the solar heat to only turn on later in the morning, then the water would heat up enough to negate the issue I described previously: so no sending a blast of cool water into your pool at start up.

There may be other issues in leaving water in the panels 24/7 that I don't know about. I know my panels hold water from about 8am to 4pm, even if the solar valve goes back to the solar-off position (like when the sun goes behind a cloud, or the pool reaches the desired temp).

The ET turns the three-way valve open/closed throughout the day if need be, depending on the pool temp and the temp at the panels. It can also control which heating system to use, based on which is available at any given point during the day or night. Since I've never used my gas heater, I'm not sure if the ET will allow both systems to be on at the same time.

Another consideration: typically the supply line feeds the lower end of the panels, the water runs upward through them, and exits the panels at their highest point. But I'm not sure if that applies to your situation. The skew of the panels relative to gravity is also important, so that the system heats most efficiently.

Anywho, you should call Heliocol support and describe your situation to determine if there is any harm (other than the freezing I described) in allowing water to remain in the panels 24/7. They may be able to suggest the proper way to plumb your panels. Then go from there. Or figure out a way to elevate the panels to be above the pool surface.
 
Last edited:

Booshy

New member
Nov 24, 2020
4
Poway CA
Hmm, I'll start with the easy answers...

Yes, the ET will control that 3-way to turn on and off the solar heater. You'll need to install an actuator on the three-way, and two temp sensors. One near the panels (which measures the heat of the air/sun on the panels) and another in the plumbing, which measures the temperature of the pool water. You would install the air sensor right next to one of the panels. The water sensor would go in between the pump and the solar valve. The ET comes with the required sensors, so maybe you already have those.

Yes I would install a Jandy 3 way actuator valve.

I don't believe I have the sensors as the pool guys didn't leave any parts. Any part numbers you can share on those?
I now show them as the purple (Air sun senser) and pink (Temp pool water) senser? I can see the pool and spa temps on the ET and phone app I just need to see where we are reading that from asht epool has 7 pumps.


solar plumbing sensors.JPG



You need a check valve on the pipe returning from the panels. That keeps water from flowing into the panels when the three-way valve is in the solar-off position. In your case, that would be doing its job whether the filter pump was on or off, because your panels are below the pool. You don't need the check valve on the supply side of the panels, the three-way valve serves that purpose. You want water flowing toward the panels when the system is heating, and the three-way will prevent flow in either direction in its solar-off position.

Got it I think this is now correct. Blue is feed and Red is return.



1606250567845.png


You didn't plot where your filter is. Typically there is a check valve between the filter and the solar three-way, which keeps "solar panel water" from back-flowing into the filter. That's seen in systems where the panels are above the pool. We'll come back to that. The panels should be after the the filter, so only filtered water goes into them.

Added Filter here. So yes filtered water into solar.

solar plumbing filter.JPG



Regarding back-flowing into the heaters: typically the return from the panels comes back into the pipe that leads into the heaters, not the way you have it. That would solve the back-flow issue. It would also allow the gas heaters to heat the solar-heated water. That would be more efficient, and get you to a desired temp quicker if you were heating up the spa during sunlight hours.

I understand and I think I fixed it now.

solar plumbing heater.JPG


Now the kicker is, I don't have any experience, nor have I read or studied how to plumb panels that are below the pool. The inherent problem is that the panels should be able to drain after the heating session is done. You don't want water sitting in the panels overnight, because the first thing you'll do the next day is pump a bunch of cold water into your pool. This is especially important if temps get to freezing at night where you live, because the expanded frozen water could destroy the panels.

I put in a call to Helocoil and will ask. I live in San Diego and not often does it get that cold. But I understand what your saying. Possible I can set this pump to come on after its had a little time to warm up a bit and then start moving water. Say 10am and then run it a little later into the night. I asumed hilliside install was ok as I found this picture when I looked up the helocoil panels and this came up.

solar plumbing hillside.JPG

Typically, the solar valve is not a normal three-way. You use a "solar drain-down" three-way, which allows water from the panels to drain down into the pool once the filter pump shuts down for the day. And there is a vacuum-relief valve installed to allow air into the panels so they can drain properly. But... I have no idea how to accomplish that when the panels are below the pool surface. I suppose you could leave the water in the panels for most of the days of the year, and then drain them before winter. You'd install a hose bib or two in the panel plumbing for that purpose. But that would be a manual task. You'd be wasting all that water if you did that daily during the colder months. Not too bad if done just once a year. If it never gets that cold down south where you are, maybe this is a non issue.

Ill ask about this as well. But good thoughts here.

If you schedule the solar heat to only turn on later in the morning, then the water would heat up enough to negate the issue I described previously: so no sending a blast of cool water into your pool at start up.

Yes I agree and good thoughts.

There may be other issues in leaving water in the panels 24/7 that I don't know about. I know my panels hold water from about 8am to 4pm, even if the solar valve goes back to the solar-off position (like when the sun goes behind a cloud, or the pool reaches the desired temp).

Ill ask and let everyone know what Helocoil says.

The ET turns the three-way valve open/closed throughout the day if need be, depending on the pool temp and the temp at the panels. It can also control which heating system to use, based on which is available at any given point during the day or night. Since I've never used my gas heater, I'm not sure if the ET will allow both systems to be on at the same time.

Another consideration: typically the supply line feeds the lower end of the panels, the water runs upward through them, and exits the panels at their highest point. But I'm not sure if that applies to your situation. The skew of the panels relative to gravity is also important, so that the system heats most efficiently.

Yes thats the way I drew it as well. Cold was the suppply side and red was the heated on top back to pool.

solar plumbing hot on top.JPG

Anywho, you should call Heliocol support and describe your situation to determine if there is any harm (other than the freezing I described) in allowing water to remain in the panels 24/7. They may be able to suggest the proper way to plumb your panels. Then go from there. Or figure out a way to elevate the panels to be above the pool surface.

Thanks and yes I placed a call easier and will let you know what they say. Also I can call a local dealer if needed.


Thanks for all your thougths and taking the time to help with this.

I appreciate that alot.
 

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Dirk

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Is there a reason you can't use your roof?
 

Booshy

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Nov 24, 2020
4
Poway CA
Pumps are about 100ft away from the house. Large yard had always planned to put in on the hillside so I didnt have to look at it on the roof.
Ground mount is already installed on hill side. I like that the panels are hidden out a view as well.
Clay tile roof so don't want people up there climbing around cracking tiles and causing issues like damage or leaks.
 

Dirk

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Understood. Let's see what Heliocol says about mounting below surface level... Surely there's a way...
 

Dirk

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Here's an article that implies panels below the pool exist. And offers suggestions about that situation, including simply running the pump during freeze conditions to keep the water moving through the panels. My system works that way for the rest of my pool plumbing, so the theory is sound. Though Murphy's Law (Chapter 73, Paragraph 4, Section 6c) demands that the worst freeze you'll get will occur during a power outage!!

 

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Desert Dog

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Apr 4, 2020
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Sorry, did not read Dirk's response in it's totality. I'll save it for later. Mine are below the pool on a slope. I have a hose bib type valve you can open to drain in the winter. You can do that or have the freeze protection activated and the pump will circulate water like Dirk mentioned. I can send pics tomorrow if it helps.
 

Dirk

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Dog, other than freeze season, does the water stay in the panels 24/7 with no problems?
 

Desert Dog

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Apr 4, 2020
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Alpine, Ca
Dog, other than freeze season, does the water stay in the panels 24/7 with no problems?
Yes, water is in the panels 24/7 when in use. In March or April, I will activate the solar heating on the ET. Before that, I will close the drain valve on the panels. The ET has my target temp programmed and will open and close the three way valve to send water to the panels or by pass them depending if I'm at my target temp. I also have a solar sensor so if it is too cloudy or night, the ET will keep the valve in bypass. The biggest advantage I see to that is the ET also adjusts the pump RPM or flow depending on if it is sending water to the panels or bypassing them.

I have it set to low RPM when not heating, and it gets a bump in RPM to push water through the panels during heating. This time of the year when it gets too cold at night to be effective I shut off the solar heating. I will then drain the panels and leave the valve open a bit just in case the diverter valve fails and I get water flowing to the panels. If I do, I will see the drip and save it from freeze damage if it gets cold enough.

In short, there is water all summer in the panels. In winter, it is drained. I'll post some picks of the plumbing but there is no other heat source, I do not have a hot tub integrated with the pool.
 

Dirk

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@Booshy, there you go. Seems simple enough. Good tip on cracking the drain valve, just in case. Probably good for air expansion/contraction as well.

@Desert Dog, so there's no need for a vacuum breaker, right? Or do you still need one just for draining the panels for winter? I suppose more than one hose bib, say at opposite corners of the solar array, might cover that. With Booshy's array of over 17 panels, maybe he'll need several hose bibs to get all the water out. Maybe one at the highest point, and then 2-4 on the bottom manifold, depending on how straight it is.

OR:

I mentioned skewing before. You could cover this issue with that as well. By skewing I mean: in addition to the return manifold being higher than the supply manifold, you rotate the entire array slightly, so that one corner of the supply manifold is lower than the other end. The corners of the upper, return manifold will follow suit. This does two things. It ensures that the circulation through the panels will be most efficient, and if you place the drain bib in the lowest corner of the supply manifold, all the water will drain to that point. This webpage shows what's going on. I learned a lot about installing and plumbing my panels from this website. The animation about skewing is towards the bottom of the page:

 

Dirk

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One more thing: I think I remember Heliocol recommending not to string too many panels together, 17 is probably over the recommended limit. Instead you create more than one array, like one of 8 and a second of 9. There's a right way and a wrong way to plumb that. The same page I reference above explains the right way.
 

Desert Dog

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I have a vacuum breaker top left side of panels. One bib for draining bottom left. Going to try to post pics now. I do not have a pic of the vacuum breaker.
 

Desert Dog

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IMG_0099.jpegHere the plumbing is exiting the filter to the left side of the pic. Through a check valve and into the diverter. Up goes to the panels, straight through it bypasses the panel. On the return from the panels (Higher pipe) it goes through another check valve and through another type of flow valve and into the salt generator. Why the second different type of flow valve? I did not plump it. Dirk any idea?
 

Desert Dog

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IMG_0100.jpegHere is the inlet to the panels. You can see one bib mounted lower than the panels on the intake for draining. I have not put a bubble level on the beam, but suspect it maybe slightly tilted to assist draining.
 

Dirk

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Here the plumbing is exiting the filter to the left side of the pic. Through a check valve and into the diverter. Up goes to the panels, straight through it bypasses the panel. On the return from the panels (Higher pipe) it goes through another check valve and through another type of flow valve and into the salt generator. Why the second different type of flow valve? I did not plump it. Dirk any idea?
Hard to tell, because I can't see everything in the pic. I believe that "other type of flow valve" is just another check valve. I used to have one like that, so it looks familiar. The two round ones, one just after the filter, and one on the solar return line are pretty typical for a solar installation. Does the square one lead to an SWG? That's old-school plumbing. Back when tab feeders were all the rage, it was prudent to put a check valve right before them, so that super-chlorine/acid-rich water that hangs around a feeder when the pump is off could not leach backwards. Typically that was to protect a heater's chemicialy-sensitive innards, but not all plumbers know the exact purpose of that check valve, so they put them just in front of tab feeders whether there is a heater or not. That then translated to SWGs, which don't actually need that check valve to protect a heater, because they don't leech chlorine/acid like a feeder does. Again, plumbers unaware of that just install a check valve before any chlorine producing device as a matter of course. That's my best guess. If you don't have a tab feeder or a heater, you could eliminate that square check valve, as it's just causing resistance to the flow. If that is a Pentair SWG just after that check, then it's supposed to have a straight run of pipe just in front of it, to allow uninterrupted flow, so it'd be all the more important to get rid of it. Which you probably can't do because there's not much extra pipe to work with. Alternately, you could remove it's flapper, that would help a little. Or if it ain't broke, don't fix it!

Hopefully Booshy can make use of some of this semi-hijack of his thread, as your plumbing pics might come in handy.
 
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