New air issue for VSP and solar heating

[Poolray]

So I've been experimenting with the different speeds on the VSP. It looks like I can run around 800-1200 RPM with no solar, and 1800-2600 with solar on. The layout is simple with the filter output going to a 3-way valve for solar with the down pipe going out to the pool. Just below the 3-way is the solar return with a Jandy check valve.With the single speed motor there were no issues with persistent air bubbles. I realize that positive pressure has to be maintained at the top of the solar panels to prevent the vacuum relief from opening and the higher speeds take care of it. But the new problem is when running low RPMs with the solar off.

At low speeds my theory is that there is no water column in the down pipe to push the check valve closed. As a result of the negative pressure, air is getting into the plumbing from the empty solar panels via the vacuum relief. Only when I kick up the speed to over 2300 does the water column rise and the bubbling stop. Now when I looked at the Jandy valve instructions they recommend mounting the valve as low as possible in the system, so that means replumbing it to be near ground level. I think that would help matters, but not sure. The only other way I can think of is to replace the check valve with an automated valve working in tandem with the 3-way, meaning $$$. That would also prevent the solar from draining down properly. Any thoughts?

 

[Isaac-1]

Can you post a few photos of the plumbing, they may help us spot something,

You may also want to lower the vacuum relief valve to the bottom corner of the panels to help with air bubble while the solar is running

 

[Poolray]

Here is one view.

 

[PrivatePilot]

Can you post a photo of the check valve? I have several in my system because of both solar and gas heaters and have no problem with them closing even on low speed....but they are naturally closed by an internal spring and only forced open when there's pressure from the correct side. Do your check valves not have springs in them so they naturally close?

 

[Poolray]

Mark,
The check valve is the one in the center of the pic. It's a new Jandy 7235 and it has a spring that holds the flapper closed.

 

[pooldv]

I don't understand how the water flow works with that set up. It seems like the 3 way valve should be on the lower pipe going to solar to the left and the check valve should be on the upper pipe returning from solar.

There are pics of my solar plumbing in my build thread, link in sig. The left pipe goes up to solar and the right pipe returns from solar.

 

[PrivatePilot]

I'm not sure how that's working either. When the solar automation valve (top one, same as what I have) opens to direct water to the left (to the solar panel?) and then returns on the bottom pipe through the check valve (?? Presuming?)...where does it go? It seems to be a loop at that point to me with nowhere for the water to return to the pool?

Unless I'm interpreting the plumbing wrong. Can you describe where each pipe is headed or coming from?

 

[PrivatePilot]

Is the line coming up from the ground the feed from the pump...or the return to the pool? I'm trying to wrap my head around the plumbing.

 

[Poolray]

Sorry, here's a more complete pic. The upper pipe going off to the left is the supply to the solar panels on the roof about 20 ft away. The lower is the return.


View attachment 47368

 

[mas985]

At low speeds my theory is that there is no water column in the down pipe to push the check valve closed. As a result of the negative pressure, air is getting into the plumbing from the empty solar panels via the vacuum relief.

Without water in the return pipe, there is no way for air to get sucked into the VRV. It is the falling water that creates a partial vacuum and draws in the air.

The air you are seeing on low speed without solar, is that in the pump basket or coming out of the returns or both? (picture looks like an air bubble in the pump basket)

It could be an air leak in the suction side of the pump.

When running on low speed without solar, do you see any water being returned from solar (via check valve) even though it is off?

 

[PrivatePilot]

Aha, ok, that makes more sense now. Your solar valve is oriented different than mine though - it's designed to swing a full 180 when the actuator is triggered which based on the way you have it installed would seem to not actually accomplish any redirection of the water - the valve would go from feeding the solar panels the way it sits in the photo...to feeding the solar when the actuator commands the valve the other way..in other words, nothing changes.

The "off" (bypass the solar) would be in the middle which the actuator, AFAIK, cannot be configured to stop at unless I've missed something about these actuators.

So, when you're testing things are you controlling the valve manually?

 

[pooldv]

Sorry, here's a more complete pic. The upper pipe going off to the left is the supply to the solar panels on the roof about 20 ft away. The lower is the return.

ok, that looks good.

 

[PrivatePilot]

FWIW, I did more reading and it seems those valves are configurable for their start/stop actuator locations...never knew that.

So, I assume the valve has been configured so that it stops at the half way point when it's actuated, and doesn't go a full 180 right?

 

[Poolray]

Right. When solar is actuated the handle is pointing up.

- - - Updated - - -

Without water in the return pipe, there is no way for air to get sucked into the VRV. It is the falling water that creates a partial vacuum and draws in the air.

The air you are seeing on low speed without solar, is that in the pump basket or coming out of the returns or both? (picture looks like an air bubble in the pump basket)

It could be an air leak in the suction side of the pump.

When running on low speed without solar, do you see any water being returned from solar (via check valve) even though it is off?

Good eye! The basket normally has no air bubbles in it at any pump speed. In this case there was some because I had just checked the drain plugs and some air got sucked in when I unscrewed the front one.

With solar off, I don't see water going thru the check valve, but the water level in the valve is less than half, and I suspect air is being pulled thru but there are no bubbles or telltale signs.

 

[PrivatePilot]

Ok everything makes sense now.

So...you think the check valve isn't sealing properly, basically...and the system is drawing air in from the panels accordingly? Air in the basket of the VSP is the main issue you're chasing, right?

Not so sure the check valve (or lesser so yet, it's location) has anything to do with that. I have the exact same check valve just before my pump, except mine has a threaded top (vs screws) for easy removal and cleaning. Other than that, it's identical, so I'm quite familiar with it. One thing I know for sure is that it's a very positive seal - the spring in there is quite strong and it takes a lot of force to open it...so I can't possibly imagine that anything coming back down from the panels would be forcing it open against even the lowest speed on the VSP.

Two possibilities I can think of - first, the spring is installed incorrectly. When you reinstall the lid the flapper valve should already be pushing on the water inlet quite forcibly - I actually have to hold it back with one finger to line up the cover and even the getting it seated can be a task. If it's just loosely hanging in there or doesn't seem to be positively sealing the spring could be installed wrong - it should be VERY tight.

Secondly...have you opened it up and checked that there's not something lodged in there that's preventing the valve from achieving a proper seal?

If neither of those turn out to be the issue, then I suspect you have a leak elsewhere upstream of the pump that's manifesting itself under low RPM conditions. With a brand new VSP myself I'm chasing suction side leaks right now although mine is manifesting the opposite of yours - air infiltration at high RPM, but minor issues (much less air) at lower RPM.

 

[Poolray]

Ok everything makes sense now.

So...you think the check valve isn't sealing properly, basically...and the system is drawing air in from the panels accordingly? Air in the basket of the VSP is the main issue you're chasing, right?

Not so sure the check valve (or lesser so yet, it's location) has anything to do with that. I have the exact same check valve just before my pump, except mine has a threaded top (vs screws) for easy removal and cleaning. Other than that, it's identical, so I'm quite familiar with it. One thing I know for sure is that it's a very positive seal - the spring in there is quite strong and it takes a lot of force to open it...so I can't possibly imagine that anything coming back down from the panels would be forcing it open against even the lowest speed on the VSP.

Two possibilities I can think of - first, the spring is installed incorrectly. When you reinstall the lid the flapper valve should already be pushing on the water inlet quite forcibly - I actually have to hold it back with one finger to line up the cover and even the getting it seated can be a task. If it's just loosely hanging in there or doesn't seem to be positively sealing the spring could be installed wrong - it should be VERY tight.

Secondly...have you opened it up and checked that there's not something lodged in there that's preventing the valve from achieving a proper seal?

If neither of those turn out to be the issue, then I suspect you have a leak elsewhere upstream of the pump that's manifesting itself under low RPM conditions. With a brand new VSP myself I'm chasing suction side leaks right now although mine is manifesting the opposite of yours - air infiltration at high RPM, but minor issues (much less air) at lower RPM.

No air in the basket, that is fine. There was some air in there from doing a test. The main problem is air bubbles coming out the return in the pool. Not the little champagne bubbles but big fart sized ones. So that means lots of air is being drawn in, somewhere. And it only happens at low speed.

I just put the check valve back together with a new repair kit. There is plenty of spring pressure holding it shut. I'm thinking there's a siphon effect in the down pipe, because the return to the pool wants to flow faster than the water coming out of the filter, hence sucking solar panel air thru the check valve. Maybe?