Solar plumbing help

[Nova13]

Ok I have vertical pipe going to roof panels this branches off with valve to bypass back to the pool.

I was going to install a vacuum relief valve about 5' above that branch leading to the panels.


I also have a pressure relief valve where does that go in the system?


I assume I need 1 or 2 back flow preventors is the system.

One on the up pipe ?

another on the feed back to the pool.

your input appreciated.



.

 

[jblizzle]

Check valves go right after the filter before the solar valve and the other on the solar return pipe before teeing back into the pool return line.

You only need a vacuum relief valve, but sure what the pressure valve you are talking about is for.

Pictures of your plan might help.

 

[pooldv]

The VRV should be installed at the end of the upper solar header opposite of the end where the water exits. If it doesn't pressurize fully then you can move it to the bottom opposite where the water enters the lower header. I also don't know anything about a pressure relief valve for solar. There are pics of my solar and check valves in my build thread, link in sig. Left pipe goes up to solar and right pipe returns from solar.

 

[Nova13]

Ok great that helps.

I thought once the temp hit's it set point and the solar valve closes, the water in the panels now not moving would heat up and build pressure requiring the need for a pressure relief valve?

 

[Isaac-1]

There are many schools of thought on placement for the VRV in an ideal world it would be at the highest point, however in the real world that can cause problems with negative siphon effect pressure sucking in air, so some people move it down to the bottom corner of the panels, lower than this is used by some installers, however the lower the VRV the greater the negative pressure the panels may see while draining, and negative pressure is a risk in collapsing the panels particularly when they are hot and the plastic is soft. As to your concern about pressure, the VRV is there to make sure the panels drain when the pump is off and the valve is closed all water should flow through the check valve on the output side of the panel and into the pool so there should be no need for a second pressure relief point. (unless you were to install the check valve backwards which would be bad) The check valves also need to be models that provide minimal back pressure (less than 1/2 psi) so watch out for those check valves that require 2+ psi to open as they will expose the panels to needless excess pressure and leave a water column in the pipes..

 

[Nova13]

ok, sound like a plan

thanks

 

[Nova13]

the pvc from the filter to the roof should I be using 1.5" or 2"

the panels are Fafco's look like 2" manifolds

I assume 2" has less resistance

 

[pooldv]

Yes, 2" is better.

 

[Nova13]

Ok, did it all in 2", runs great in few hours the temp got up to 88.

I see bubbles in the pool return outlet's, flipped the valve to shut solar loop gone.

I can hear a lot of water gurgling on the down stream pipe, I installed a drain for the winter on that drain side, opened and water pressure is low but flowing.

I'm using a smaller than normal pump, may need to add a booster pump on the up stream pipe????


don't know if there is such a thing in 2", I have 5 panels, was told I need about 12 gpm flow.


Or are these bubbles from someplace else, went on the roof found a small leak at rubber boot tightened that made no difference, all other fittings are dry.

 

[jblizzle]

Where did you put the VRV?

How long did you run and still see bubbles?

 

[Nova13]

Ok, did it all in 2", runs great in few hours the temp got up to 88.

I see bubbles in the pool return outlet's, flipped the valve to shut solar loop gone.

I can hear a lot of water gurgling on the down stream pipe, I installed a drain for the winter on that drain side, opened and water pressure is low but flowing.

I'm using a smaller than normal pump, may need to add a booster pump on the up stream pipe????


don't know if there is such a thing in 2", I have 5 panels, was told I need about 12 gpm flow.


Or are these bubbles from someplace else, went on the roof found a small leak at rubber boot tightened that made no difference, all other fittings are dry.

 

[Nova13]

Where did you put the VRV?

How long did you run and still see bubbles?

vrv in first pic just below roof

bubbles in 5 minutes

 

[jblizzle]

Bubbles started in 5 minutes or lasted 5 minutes? There is always air that needs to be purged from the panels every time you start the solar.

 

[Nova13]

no they go all day

 

[jblizzle]

Try plugging the VRV briefly and see if the bubbles stop (remove and plug it). If they do, then you might have to lower the height of the VRV.

As a note, it is generally not recommended to use all those DWV fittings that you used which are not pressure rated as high. You may have no issues, but keep an eye on them. Also the check valve you used adds a lot of head loss lower the flow rate. And those ball valves tend to get stiff and the handles break off.

 

[Isaac-1]

Where were you told 12 GPM flow, that sounds WAY too low, optimal flow for most 4x12 panels is around 4.5 GPM per panel, with a minimal flow of about 3 GPM per panel (at this minimal they take about a 10-15% performance hit, dropping under 3 GPM per panel and performance drops off fast).

Ike

p.s. do you know the specs on that check valve, those style check valves can add anywhere from 1/2 to 3 psi of added back pressure

 

[Nova13]

Try plugging the VRV briefly and see if the bubbles stop (remove and plug it). If they do, then you might have to lower the height of the VRV.

good idea to test it, I'll try that.

As a note, it is generally not recommended to use all those DWV fittings that you used which are not pressure rated as high. You may have no issues, but keep an eye on them. Also the check valve you used adds a lot of head loss lower the flow rate. And those ball valves tend to get stiff and the handles break off.

the small pump is not high pressure, I intend to paint all of them, UV breaks the glue in joints if not painted.

what other type of check valves are there?

the ball valves are only temporarily until iget the bugs out then add the electronic ball valve with thermostats etc.

.

 

[Nova13]

Where were you told 12 GPM flow, that sounds WAY too low, optimal flow for most 4x12 panels is around 4.5 GPM per panel, with a minimal flow of about 3 GPM per panel (at this minimal they take about a 10-15% performance hit, dropping under 3 GPM per panel and performance drops off fast).

right now w/o temp controls the pool is hitting 100 degrees???

So the flow rate must be working, not 100% sure, I have some flow meters I was going to add, that's the only way I'll know for sure.

But if it's not enough, where can I find booster pumps that may work?

Ike

p.s. do you know the specs on that check valve, those style check valves can add anywhere from 1/2 to 3 psi of added back pressure

have any suggestions?

 

[pooldv]

Here are some good check valves. Pool Check Valves. Swimming Pool Check Valves.

Here is a good solar valve to use, Pentair 3 Way Solar Valve with Drain Down 263047 | Pentair 263047

 

[Isaac-1]

I too was going to mention the flovis option, where you get check valve and flow meter all in one.