How to turn off solar heater?

caycarem

LifeTime Supporter
May 16, 2009
90
Hayward, CA
Hi,
My solar heater does not have any checkvalves it seems, how do I best turn off and on? Can I leave the valve going up and return always open, 3 way valve open, then just let the pump turn on and off daily? Or do I need to close the 3 way valve first before turning pump off? I’m worried water coming back down into the filter.
Thanks!
 

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Dirk

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Nov 12, 2017
6,888
Central California
You need a check valve between the three-way solar valve and the filter. They're pretty easy to install.

I also have a check valve on the return side of the panels, the diagram below shows that one as optional.

The three-way solar valve should be specifically for solar panels. It should have a drain-down valve in it, which allows water from the panels to drain down through the three-way valve when the pump shuts down, even when the valve is in its "solar off" position.

The water should all drain down out of the panels at the end of the heating period, all through the return side of the plumbing (back to the pool), none back through the filter (you should be worried about that).

You should not be manually adjusting any valves. Your solar valve should have an actuator on it, which should be controlled by the solar controller. When it's done for the day, the controller will put the valve in the correct position (solar off) and no other valves should have to be adjusted by you.

Assuming you have the actuator (I can't tell in your pic), all you need to do is install the missing check valve(s) and confirm you have a solar drain-down three-way diverter valve with actuator (replace it with one if you don't).

I suppose there is a way to achieve proper shut off manually with what you have, but I'm advising you how to get your system fixed correctly rather than how to run it incorrectly (especially since the fix would be so cheap and easy).

If the answer(s) to your question(s) was not in there somewhere, let me know...

unnamed.jpg
 

caycarem

LifeTime Supporter
May 16, 2009
90
Hayward, CA
Thank you Dirk, that was very helpful. I checked again and I have think it has what look like a check valve coming out of the filter on the picture. Also the solar 3 way valve is Hayward GVA-24 with actuator, do you think it has drain down inside? Sounds like if it does i can just leave solar on and let pump turn on off without any manual intervention? seem like they placed the solar valve at the end of the solar return to save a check valve.

couple other questions:
- I don’t see any vacuum relief valve, the top end on roof was sealed with end cap. Would this be bad?
- pool Filter is at 8psi without solar, 13psi with solar on, and 20psi with solar and spa mode ( pump suction and return line valve switched to spa). spa mode without solar is about 15 psi. Does this seem normal? Can the old panels with some leak plugs handle 20psi (assuming it is 20 psi up on the roof)? solar system is pretty old, installed in 2008.
-there's a small copper valve connecting the copper return line from heater to the spa return line, by passing the pool/spa return valve. do you know what its purpose is? seems hard to turn and I'm afraid to turn it too hard and cause a leak.
 

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Dirk

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Nov 12, 2017
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The two three-ways in pic 2 do not appear to be part of the solar plumbing, those are for the spa, as near as I can tell. You do seem to have a check valve after the filter, I can't quite make it out though. The solar plumbing does not appear to be done correctly, but again, it's hard to tell from the pics.

I'd be happy to help you, but this is what I'd need. What you need. Create a schematic-type diagram, like the one I posted, that plots out all the plumbing and valves and other components, so I can see what's going on. Do it carefully, it'd be easy to get wrong with the spaghetti you've got going on there.

- You absolutely have to have a vacuum relief valve. It's really bad for the plumbing on the roof if it's missing. But it may not be on the roof. Mine is under my roof eve. Do you know what to look for? Confirm it's there or not.

Sorry, I'm not well-versed on translating a filter valve's PSI into anything meaningful. I installed a FlowVis to help me track all the various flow scenarios. There is a way to do that, somewhat less accurately, with the pressure gauge, but I don't know how to do that. We can get into the FlowVis topic more once I see your schematic. To answer the rest of that question: can you track down the name of the manufacturer of the panels and/or any owner manuals?

Regarding the mystery copper valve, include that in your schematic and I'm sure we'll be able to figure that out, too. It might be some sort of bypass, maybe to keep a small amount of water flowing though the spa, for sanitization, even when the big valves are set to pool mode.

There's just no way to get a handle on everything from those pictures, especially when your system is so crammed together as it is. So more later...
 

Dirk

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Nov 12, 2017
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Central California
The Hayward GVA-24 is the actuator (which means you have one). That's not the valve. You need to dig deeper to get the valve model number, if you can. That component of the solar system is two parts, the valve and the actuator. The actuator is the rectangular part, which bolts to the valve, which has the PVC pipes running to and from it. That rounded PVC part is the one we need to identify.

I see now, in the first set of pics, the solar valve. Yes, it appears to be on the return side of the panels. I've never seen that before, but that doesn't mean it won't work like that. The schematic might better answer that question.
 

caycarem

LifeTime Supporter
May 16, 2009
90
Hayward, CA
Yes you are right on, we moved into this place recently and the pool is new to me, so I'm trying to figure things out. Diablo Solar company installed the solar heater in 2008, yesterday I managed to replaced 3 of 9 fafco panels and repaired 2, and just starting to use the solar system. there are much left to be done unfortunately, to this new spaghetti setup, but the pool is really nice and the kids love it, so I am planning to slowly upgrade stuff.

i have set the solar controller to Automatic heating at 85F earlier today, it seemed to turn off itself correctly at sun down so that was good. guess I'll have to do something about the vacuum relief situation as i don't see one anywhere.

running 20psi spa+solar for a few hours caused header connection to leak in one of the panels but tightening the connector bracket fixed the issue. there could be a new tube leak on an old panel i'll have to check.

I will make the schematic later. Thanks for your thoughts on the spa bypass valve, I think you may be right as i do see small amount of water going into the spa even with the 3 way return spa valve is pointing to the pool side.
 

Dirk

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Nov 12, 2017
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Without a vacuum breaker, once the pump goes off, the weight of the water on the roof will "suck" the PVC pipes and the panels in on themselves. If the material is hot enough, that can deform the PVC and tear apart the panels, especially where they connect to the manifolds. That might be happening, and why you had leaks. It would be incredibly bone-headed of a solar installer not to install a breaker though, so I'm wonder if you just haven't found it yet. Nothing on the roof? They can be as low as about 6' off the ground, so it might be just above your pad. Nothing there?

When my panels drain, the breaker croaks like a frog. It's pretty obvious. Heard anything like that?
 
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Dirk

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Nov 12, 2017
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I determined my pump RPMs for my solar-on mode by first getting the optimum flow rate for my panels from the manufacturer (5 GPM per panel x 8 panels = 40 GPM), and then using a flow meter to set the pump RPMs to achieve exactly 40 GPM. So I know my panels are not getting too much or too little flow (or pressure). Which means they are heating my pool in the most cost-effective way possible. I think there is a way to do that with the filter pressure gauge, but I don't know how, sorry. That's why I bought the meter, so I wouldn't have to figure that out! ;)

The leak from the manifold connection might have had nothing to do with the 20 PSI. That radiator-hose-style connection (if that's what you have) is notorious for leaking, because the connector hose is exposed to the sun. It expands and contracts and dries out. So you have to tighten or replace them periodically. That's "normal" for that type of connection.
 
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Dirk

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Nov 12, 2017
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This from a Fafco installation manual. Perhaps you have a breaker hidden in one of the end caps:

VACUUM RELIEF AND END CAPS
1. The vacuum relief valve (identified by two holes in cap) should be used to seal the top header on
END panels (place in the highest point of the system). Use 1 vacuum relief per system or per bank.
2. End caps are used to seal headers on end panels.
 

Dirk

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I don't know your Fafco model, but I sniffed around a bit on the 'net. I found some instructions for how to optimize the panels with the filter gauge. I also found a set of spec's that suggest some model of Fafco panels can handle up to 30 PSI regularly, and a peak pressure of 45 PSI. I also found min, max and optimum flow rates. I can't say how what I found applies to your panels, or even if 20PSI on the filter gauge means 20PSI on the panels (I don't know enough about pool plumbing head and pressure.) More to the point: Fafco will have all this information, either on their site, or by contacting their customer service. Which means you'll be able to adjust your system to get best heating at least cost if you hunt down the info for your model of panels.
 

YonnyPiscinas

Well-known member
Jan 10, 2020
117
Uruguay - SA
Without a vacuum breaker, once the pump goes off, the weight of the water on the roof will "suck" the PVC pipes and the panels in on themselves. If the material is hot enough, that can deform the PVC and tear apart the panels, especially where they connect to the manifolds. That might be happening, and why you had leaks. It would be incredibly bone-headed of a solar installer not to install a breaker though, so I'm wonder if you just haven't found it yet. Nothing on the roof? They can be as low as about 6' off the ground, so it might be just above your pad. Nothing there?

When my panels drain, the breaker croaks like a frog. It's pretty obvious. Heard anything like that?
This is what happened to mine last summer - I need to get a vacuum release valve in very soon as the summer is arriving here in Uruguay - do not want a repeat of what happened last Feb. Temps were reaching 65c in the sun on the roof in mid summer. Oct now and the pool is already 31c! Spring weather but very variable. 30c yesterday. Tomorrow's max of 13c
 

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Dirk

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Nov 12, 2017
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I can't find anything definitive that the Hayward PSV3S2 is a solar drain-down valve. That's not to say it isn't, just that I can't find it. Because the three-way is in that somewhat non-standard location, on the return side, I think most of the roof system, including the little tubes of the panels, will drain down through the supply side, but water would still be trapped in some of the PVC on the return side. I honestly don't know if that's 100% true, nor if that matters all that much. I just know my system drains completely, return and supply, which is ideal. I actually went the extra mile and tilted my panels and supply PVC pipes slightly, so very little water remains in the horizontal runs. But that's a different matter.

We can review this if you complete the schematic. Or if the original installer can be found, maybe they can verify that your panels drain correctly because of the way they plumbed the system.

I can't read the valve's sticker in the pic. Does that indicate anything about "solar" or "drain down" or any other clue?
 

Dirk

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Yep, I had already perused that earlier today. I searched that PDF for "solar" and "drain" and even "down" and no hits. Which is why I all but said you don't have a solar drain-down valve. I think it's just a normal three-way valve. Because your solar panel supply pipe is tee'd off of the main plumbing line, all the time, no matter which way the solar valve is turned, when the pump goes off, the upper manifold, all the little tubes, and the lower manifold will all drain down through that supply pipe and that water will run to the pool as it should. But if the solar-valve is in the "solar off" position, then the water in the return pipe, all the up way to its highest point on the roof, would be trapped unless that valve has a drain down flapper inside it.

I'm not sure if you can manually operate a valve that's connected to an actuator. If you can, there's an easy enough way to test this. Run your pump and engage the solar system. Let the system fill with water until no more bubbles come out of the pool returns. Give it a few minutes. Then turn off the solar system and then turn off the pump. You should hear and/or feel water draining down the solar supply pipe. It might take a while, give it 15 or 20 minutes, or until you don't hear any more water draining down through that pipe. Now, without turning on the pump, manually turn the solar valve from "solar off" position to "solar on" position. If you now hear water coming down through the solar return pipe, that confirms that (1) the valve is trapping water in that pipe, and (2) it's not a solar drain down valve.

On my system, I can have the pump off and work my solar valve by flipping its little override switch. You might try that before trying to force the valve and actuator manually. It just depends on how your system is wired.

As I mentioned, the entire system should drain. The primary reason is so that the trapped water doesn't freeze overnight. A less important reason is so that when you first engage the solar heater in the morning, you don't get a flood of cool water into your pool. There may be other reasons, too, that I'm not thinking of. Not sure.

Your system might very well work just fine as is. It probably has been for 12 years. I'm only pointing out it's not how it's typically done, and I don't know if there are any long-term reasons that might be less than ideal.
 

caycarem

LifeTime Supporter
May 16, 2009
90
Hayward, CA
I can manually switch solar on and off using the controller. last night about 4 hours after pump was off with solar off, I turned on solar but did not hear any water flow, it seemed to have drained down by then (or not moving at all), not sure supply or return line, then i put controller back to automatic and it turned solar off. 8:30am i went to check, solar valve was already open. when i turned on the pump, a lot of cold water came out into the pool for a few minutes. so I guess some water was still in the panels over night. I will pay more attention tonight when i turn off the pump.
 

Dirk

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Nov 12, 2017
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Your pipes are marked with a black sharpie. The up arrow in the supply pipe, the down arrow is the return pipe. You didn't do that test I suggested correctly. And your conclusion about the water flowing into the pool this morning is not valid. Have another read, and another go at it, and report back. Ask me if the instructions are not clear.
 

caycarem

LifeTime Supporter
May 16, 2009
90
Hayward, CA
Ok I followed your suggested steps this time, with running solar, i put solar valve to off, then turned off pump. I heard water coming down supply line at first, then few minutes later they seemed to come down on both supply and return lines for a few more times, few minutes before each occurence. When no more water coming down, I turned on solar valve via controller, and I didn’t hear water coming down the return pipe. Maybe it does have drain down valve even when solar is off!
I did notice clicking sounds but only for about a minute at the solar valve right after i turned on the pump. Is this normal?
 

Dirk

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Nov 12, 2017
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Central California
Not sure what the clicking sounds are about. Perhaps something to do with the Hayward actuator? I don't have that brand.

The drain-down experiment sounds like a success. So maybe it is a drain down solar valve. Or... some guys will modify a regular valve by drilling a hole inside, in essence converting it to a drain-down valve, which then allows the water to drain. No matter. As I said, if it's been working for 12 years and still seems to be working now, then I'd say you're squared away.

If you don't want to go down the flow meter path, then search for the owner manual for the Fafco panels you have. The Fafco manual I found describes a way to set your flow rate using the filter gauge. Or contact Fafco support and see if they can walk you through it.

I took you for a bit of a ride there. Did we cover everything so far?