vacuum release valve location for solar panels, etc.

[haz]

Thanks to you all for all the help with the issues I had getting my nine Heliocol HC-50 solar panels to work:
http://www.troublefreepool.com/pump-power-w-different-impellers-2-speed-vs-vs-w-solar-t70827.html

Unfortunately as time went on, I found out that my installer knew less and less about solar. At this point I'm on my own in terms of trying to fix the small things. Hopefully I never need any warranty repairs from them...

One of the things they didn't install was a vacuum release valve. I asked the owner, and he said they're "not needed in this climate" in South Florida. His tech doesn't know how to adjust the valves on a solar system with a split after the filter to get water up to the solar panels, and he didn't install a check valve on the outflow, so I don't believe his answers. I think he may have been confused with a drain valve used in freezing weather.

Anyway, from what I've read here, everyone recommended a vacuum release valve to
1) prevent collapse of the panels from negative pressure
2) prevent overheating of the PVC pipes from the heating of stagnant water in the pipes
3) prevent cooling of water in the solar panels overnight from convection on cool nights, and that water then being returned to the pool in the morning

The opinions here on location for a vacuum release valve (VRV) vary from
1) the solar inflow pipe past the solar valve above the height of the pool level, for easy access
2) the top of the panels
3) anywhere in between

I don't know if location matters based on the height of my panels or whether I'm in a freezing-prone area, which I'm not.
The bottom of my panels are around 23' above the pool level.

I will be having to tell someone who might know about plumbing/pools where to install the VRV, but unfortunately they probably won't know anything about adjusting them, etc. If I have to install it on my roof, then i need someone who can get up a 23' roof, and then I won't be able to get up there to adjust them, which I currently don't know how to do anyway.

What do you recommend in terms of
1) location of installation
2) brand/type of VRV to install

Also, I'm also going to have the ball check valve they installed below the solar 3-way valve changed for a lower-head Jandy:
http://www.zodiacpoolsystems.com/Products/Valves/Check-Valve.aspx

I have 2" PVC pipes. They list one size:
7235 Jandy Pro Series 180Degree, 1 1/2" - 2" Check Valve
and another:
7305 Jandy Pro Series 180Degree, 2" - 21/2" Check Valve

both overlap at 2". Should I get the bigger or the smaller one?

They also didn't install a check valve on the outflow. I was going to have a FloVis flow meter installed on the outflow near where shown in the picture below, above the red manual valve they installed on the outflow. My question was - the reason that I was recommended by people here to put the check valve was to prevent back flow into the outflow pipes that could go up into the panels, which could lead to the problems #2 & 3 in my list above as to why I think I need a vacuum release valve. However, I have a 2-speed 2.0 HP pump, and when solar is off, unless my pool feature is on, which is maybe 10 minutes a day, the pump is always in low-speed mode. This should not be able to generate enough head to get any water into my panels, I don't think, and with a VRV, the panels should drain. Given the extra head that the outflow VRV will give me, do I really need an outflow pipe check valve? If not, where would I put my FloVis flow meter? I think it couldn't be instead of the check valve I need to change, since that's before the solar valve.

Also, if anyone know someone in South Florida who knows about solar stuff that I could contract to do these changes, that would be appreciated. I know it's simple plumbing for most of you, but otherwise I'll probably get my pool guy or one my pool installation contractor's guys, who don't know about solar, to help with these things.

Thanks!

 

[Isaac-1]

Ok, first off there is debate on best place for vacuum release valve, but I would suggest bottom of the panels to be the best compromise, particularly with how high your panels are. If you put it all the way to the top then this increases chance of water leak at the vacuum release valve (it should work at the top, but in the real world you might either get slight negative pressure there or a slightly sticking VRV) Putting it near ground level means easier access, but greater negative pressure the panels will see. There are several VRV valve options, some are built just for solar panels, others are general purpose plumbing parts. The one that came with my Techno Solis panels is a common brass Watts brand N36 3/4 inch VRV screwed into a reduction end cap fitting. http://www.watts.com/pages/_products_de ... sp?pid=815 (they also make a similar lead free LFN-36) These fittings are often available at Lowes and other big box home stores. For proper operation this type of VRV should be installed so it faces up, thee is no adjustment to be made, just replace if it leaks.

Simplest installation of the VRV would probably be to get a 2 inch PVC T fitting with a 3/4 inch threaded leg on the T and the 3/4 inch VRV mentioned above and install it near the feed point for your panels, should be a 5 -10 minute job. Just remember to thell the installer to make sure it points up.

Everything else looks like a good plan, but I would replace that red handled ball valve with something more durable while you are at it, those tend to swell with age and get hard to turn, then the handles break off. If you don't replace it now make sure to leave enough space to cut the fitting out later or else you may find yourself without enough stub to reuse the flowmeter when you do have to change the valve.

While your at it I would also consider adding a T with a drain spigot, just in case.

Ike

 

[haz]

Thanks, Ike. That would be much easier if I can put the vacuum release valve near the bottom.

Simplest installation of the VRV would probably be to ... install it near the feed point for your panels ... Just remember to thell the installer to make sure it points up.

Would pointing it up be OK on a non-horizontal segment, like in my picture below? I figure it needs to be past the solar valve, or when that shuts off, air won't get up to the panels. Otherwise the next horizontal segments are just before the roof.

I would replace that red handled ball valve with something more durable while you are at it

What type of valve would you replace it with? Do I need a manual valve there?

While your at it I would also consider adding a T with a drain spigot, just in case.

Where would you put that? Would that be facing down from a horizontal segment, or maybe from that same diagonal segment?

 

[Isaac-1]

Ok time for a little math, and then you can decide what to do, you say your panels are 23 feet above the pool level, is this to the top of the panels or the bottom? Assuming this is the bottom of the panels and your roof has a moderate slant that will put the top of the panels somewhere around 27 feet above the pool surface. Water exerts a pressure of 1 atmosphere (14.7 psi) for every 34 feet of fresh water column, This also means it can created a vacuum of about the same. In your photos I would estimate your proposed VRV location is about 4 feet above the pool surface, and therefore about 23 feet from the top of the panels. 23/34 x 14.7 = 9.94 psi of suction on the tubes at the top of the panel, leaving there potential interior pressure at only about 4.7 psi in a 14.7 psi atmosphere. Keep in mind that these plastic panels and PVC pipe can become soft when under sunlight.

Now watch this youtube video on the effects of vacuum, specifically a vrv not working right in an extreme situation http://www.youtube.com/watch?v=y5VRww1Ypwk

I am not saying this is what would happen to your panels with a ground level VRV, I am just saying it might be a safer idea to install it as high as practical.

As to your other questions, yes that looks ok for a drain spigot.

I would install a manual valve there if for no other reason that it lets you positively isolate the return on the panels if you get a leak, you may also want one on the input side if your 3 way valve is a "solar" valve that has a little built in check valve.

As to type of valve, ideally if money were no object I would pick something like a Jandy 2876, but there are many other cheaper options, alternatively you could us something like this http://www.aqua-man.com/itemMatrix_all. ... Code=M5921 which can be removed and have the core part replaced without cutting the pipe.

Ike

 

[haz]

I am not saying this is what would happen to your panels with a ground level VRV, I am just saying it might be a safer idea to install it as high as practical.

So you think anywhere along the pipes in the photos below marked with a red line are good locations and better than putting them lower. I hope it's not difficult to adjust them, that's my issue with putting them so high.

I would install a manual valve there if for no other reason that it lets you positively isolate the return on the panels if you get a leak, you may also want one on the input side if your 3 way valve is a "solar" valve that has a little built in check valve.

My valve is a HaywardGoldline valve actuator gva-24:
http://www.hayward-pool.com/pdf/manuals/ValveActuatorGVA-24.pdf

It's not specifically a solar valve, so I figure it completely isolates the solar off when turned off, so no need for a manual on the input side, no?

 

[Isaac-1]

Yes, anywhere on the red line on the roof would work, probably the easiest option would be to remove the elbow on the roof, and splice in a T with a reduction fitting and threaded street elbow make the VRV point up. There is nothing to adjust, just unscrew, and replace if it fails. The GVA-24 is the Actuator, the valve under is either a full shut off valve, or was and someone drilled pin hole in it to allow draining, or is a factory "solar" valve with built in check valve. Drilling standard valves for draining is a common practice for solar installers.
http://akroncanton.craigslist.org/for/4252307356.html

Ike

p.s. splicing in a T for the VRV under the eave might be even easier

 

[haz]

Thanks! I'm going to go look for the VRV and T pipe

Yes, anywhere on the red line on the roof would work, probably the easiest option would be to remove the elbow on the roof, and splice in a T with a reduction fitting and threaded street elbow make the VRV point up. splicing in a T for the VRV under the eave might be even easier

So I think you're suggesting either of the 2 areas marked #1 in the photo below, and your original suggestion is #2, correct?. I think #1 would be easier, as no need to go on roof itself, just a ladder.

The GVA-24 is the Actuator, the valve under is either a full shut off valve, or was and someone drilled pin hole in it to allow draining, or is a factory "solar" valve with built in check valve. Drilling standard valves for draining is a common practice for solar installers.

Is there a way I can tell if they drilled a pin hole in the valve? I wouldn't expect them to do it given how they did things in general and the fact that they didn't instal a VRV because they don't think it's necessary. If there is a pin hole, then I figure a good location for a manual valve on the inflow would be as indicated in the 2nd picture below.

Does this all sound right?

 

[Isaac-1]

Yes, either #1 or #2 for the VRV, should work well and be fairly easy to splice into.

As to the pin hole question, the easiest option I can think of is to make the cut for splicing in at the point where you have "manual valve for solar input marked and fill with water with the existing valve set to bypass. If water drains it has a pin hole, if not it does not. At this point you could decide to not add the valve and just put in a coupler.

You might be able to open it and watch to water back feeding down once the vacuum breaker is installed and before adding a feed side check valve, a wider angle photo of your pad may help on exactly how.

 

[haz]

Thanks. Was out during the holidays - pardon my late reply.

As to the pin hole question, the easiest option I can think of is to make the cut for splicing in at the point where you have "manual valve for solar input marked and fill with water with the existing valve set to bypass. If water drains it has a pin hole, if not it does not. At this point you could decide to not add the valve and just put in a coupler.

It sounds like I need at least a specific solar valve or a regular valve w/ a pin hole. So if there's no water drainage after filling it with water, I need to drill a hole in the valve. Any particular size of hole?

You might be able to open it and watch to water back feeding down once the vacuum breaker is installed and before adding a feed side check valve, a wider angle photo of your pad may help on exactly how.

Here's a wider angel of the area where the solar branches off: