Homemade solar heater and check valves - are check valves required

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papaflbear

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Feb 16, 2013
17
I'm constructing a homemade solar heater and I'm wondering if I need a check valve after the filter before the solar. I see that most all diagrams show the check valve after the filter but looking at the check valve from Lowes, it looks like it would really restrict the flow. I have an 18000 gallon gunite pool, Intelliflo VF pump, 420 sf cartridge filter, and have what I think is a pretty efficient piping/pump setup. I run the pump for 12 hours a day at 25 gpm and it takes about 175 watts for the pump to function at that flow. So I don't want to impact that efficiency very much when I'm not using solar. Since this is a cartridge filter, is there any harm if water does back flow thru the filter. If it's okay for that to occur, do I need a check valve after the filter?

Thanks

Ken
 
Thanks to both of you for the quick reply.

The solar is on the roof about 8' above the pump equipment on the low end and the high end is about 11' high. About 10' of pipe to get to the low end manifold. My "panels" are 100' coils of 1/2" irrigation poly tubing within a 34" frame, 12 units total...not fancy by a long shot. I just hope they work okay.

And Surf Hawk, I just thought of the Jandy or Pentair check valves after I posted my question. I don't know why I didn't think of them earlier.... and I was just by SCP on Wednesday. So I'm going to pick up one of them on Monday. So darn frustrating to forget about the Jandy valves.

Thanks
 
Just curious, how much did your setup cost? I have a very old solar system made of copper and aluminum, operating at about 75% capacity because of having to plug leaks.

I think the way my system is plumbed, if I am bypassing my solar, water could shoot up the solar return line if I don't have a check valve.
 
Surf Hawk said:
Just curious, how much did your setup cost? I have a very old solar system made of copper and aluminum, operating at about 75% capacity because of having to plug leaks.

I think the way my system is plumbed, if I am bypassing my solar, water could shoot up the solar return line if I don't have a check valve.
Click to expand...

I have about $260 in material cost....before the Jandy valves. I already had some of the frame material and the aluminum for the frames back. That saved me about $100 or so.

And I think a check valve is needed on the solar return as water could flow that direction when the solar is bypassed.
 
I hope the 12 coils are in parallel right?

You will want a check valve on the solar return. The one after the filter is most for when the panels drain, but with coils, I am not sure how well they will drain anyway. Did you put a vacuum release valve on the roof too?

FYI, solar heating is all about sqft of sun exposure ... with 1200' of 1/2" tube, you have a little over 50 sqft of exposure. My pool originally had 2500' of 1" tube which was around 200 sqft of exposure and that was not enough for me. And there were always new leaks (but mine was not coiled). I now have 500 sqft of panels.

Point is 50sqft is not very much exposure and on Ebay you can get 40sqft solar panels that are more efficient for < $100 ... DIY generally is not the most cost effective solution anymore.
 
jblizzle said:
I hope the 12 coils are in parallel right?

You will want a check valve on the solar return. The one after the filter is most for when the panels drain, but with coils, I am not sure how well they will drain anyway. Did you put a vacuum release valve on the roof too?

FYI, solar heating is all about sqft of sun exposure ... with 1200' of 1/2" tube, you have a little over 50 sqft of exposure. My pool originally had 2500' of 1" tube which was around 200 sqft of exposure and that was not enough for me. And there were always new leaks (but mine was not coiled). I now have 500 sqft of panels.

Point is 50sqft is not very much exposure and on Ebay you can get 40sqft solar panels that are more efficient for < $100 ... DIY generally is not the most cost effective solution anymore.
Click to expand...

Jason, yes I have a vacuum relief valve but I'm wondering how well the coils will drain too. Seems like they would need a siphon effect to empty completely. I have the eight coils in parallel but the last row of 4 are in series with the middle row. I initially was going to have 4 panels connected in series of 3 each thinking that they would gain more heat but I found out that 1/2" poly can only flow 5 gpm giving me a total flow capacity of only 20 gpm. So I changed my setup so I have 8 connectors to the intake manifold and 8 to the discharge manifold. I connected the top row of 4 in series with the middle row. I don't know how it will work though but hopefully it will work.
And yes I know that my total sf is not much. I searched some on Ebay but didn't find any panels that were cheap enough for me at the time. I live in Florida so that may help too. Anyways, once I get the check valves I'll see how this works.

Another question, Is it necessary to have a 3 way drain down valve? I have regular Jandy 3 way that I was intending to use.
 
You would only need the "solar" valve or adding a hole to the 3-way diverter if it is on automation and turns off the solar every evening. If your is manual, then I would guess you are going to leave the solar valve open.
 
jblizzle said:
You would only need the "solar" valve or adding a hole to the 3-way diverter if it is on automation and turns off the solar every evening. If your is manual, then I would guess you are going to leave the solar valve open.
Click to expand...

I'm planning on connecting to my Intellitouch panel and only have the solar on part time. Can I use the 3 way diverter if I drill a hole in it? What size hole should that be? If you drill a hole in the diverter, doesn't water flow thru the hole when the solar is closed? It seems like it would when the pump is on.
 

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Just search "pool solar panel". There are 2x20 panels for under $100 or 4x20 for under $180.

I have no idea of the quality and longevity, but for less than the cost of a diy build likely worth a shot.
 
Thanks for the suggestions. The problem is my roof area is only 16' in length or 12' rake height. I would have to install the panels on the second story roof and I didn't want to go that route yet. I may end up with having to put them on the second story but guess I'll try the coil tubing on the lower roof area since I have those already built. Thanks again.
 
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