VRV - bubbles

[Ryano2121]

I am a new pool owner. 13k gal with six 4x10 panels on the second story roof and a new Intellifo VS.

I've read a lot and am working on getting my solar to be efficient.

I've always had the waterfall running but switched it to the pool outlets today. I had a lot of bubbles running at 2150 rpm with the system fully primed. Bumped it up to 2350 and have very few, very tiny bubbles.

Does this mean the vrv is not fully closed at the slower speed? If it is not fully closed, efficiency is lost right? Is it correct that I want to run at the speed which does not create bubbles? From my reading, 2150 rpm should be enough gpm for the sqft of my panels.

I've read about vrv's that do not function properly. Should I climb up at look at it? If so, what am I looking for?

Thanks!

 

[jblizzle]

I would suspect that the VRV might not be working. You could try replacing it and see if that helps. With the VRV being on the 2nd story, you are going to have to run at a decent RPM to get enough pressure up there to keep it closed.

The VRV really has nothing to do with adequate flow for the solar panels. With those 6 panels, you only need ~24 GPM for the heating, so you are going to likely need to bypass some of the water.

 

[Ryano2121]

If I am going to replace it, would it be better to put it somewhere else?

 

[jblizzle]

There are trade offs. The lower in the system, the easier to keep closed, but it also allows a high vacuum to be placed on the panels when they drain.
Mine is on low side of the panels where the water enters on a single story roof.

 

[Ryano2121]

It looks like these are threaded. If it isn't where I want it, how do I put it in?

 

[mas985]

Do the bubbles ever go away at any speed? I hate for you to replace the valve if there is nothing wrong with it.

Also, what is the height of the VRV relative to the pressure gauge and what are the pressures at the various speeds?

 

[Ryano2121]

The bubble are gone at 2350, but I'd like to run slower than that for energy savings if I can.

The VRV must be on the roof but I haven't been up there yet.

At 2350 it's 18psi, at 1750 it's 9psi.

 

[Ryano2121]

Well the psi I provided are not right. The previous owner said the filters had just been cleaned and I trusted him. Opened it up today and that wasn't true. The water was almost black with a oil slick film on top. There was 2" of dirt in the bottom. The cartridges are so filled with dirt that after 15 min of washing one there is still dirt coming out. Replacing them with new tomorrow. It will be interesting to see how the psi looks and if there are bubbles at lower speeds.

 

[mas985]

That was probably causing your issue. 9 times out of ten it is a dirty filter causing the VRV to open up.

Also for future reference, for a two story house, you need at least 12 PSI at the filter (clean) and maybe more depending on the actual height of the VRV. As the filter gets dirtier, the pressure required is higher because you need to account for the filter drop.

 

[Ryano2121]

What happens if the vrv is not fully closed?

With new cartridges and a new pressure gauge, I'm at 13psi, 2200rpm, 640 watts with no bubbles.

Priming at 2900rpm for 3 minutes, the time it takes for no air in solar return. I lowered the priming speed and ran it longer to reduce pressure at the panels. Before it primed at 3450rpm for 30 seconds and there was still air coming through after priming stopped.

 

[mas985]

The VRV will suck air if it doesn't close which is why you see the bubbles.

 

[ed65roc]

The VRV will suck air if it doesn't close which is why you see the bubbles.

Hi-

I have a new Heliocol system and I too have a lot of bubbles each time the solar valve opens, and when the pump shuts off I can hear the VRV sucking air to allow the panels to drain. I have low flow rates due to a long plumbing run from the pool.

I must be missing something, as I would expect that the purpose of the VRV is to LET air into the system to break the vacuum. Perhaps I'm misunderstanding something. Are the bubbles an issue? I live in CA, and there is little risk of freezing; perhaps I'll just remove the VRV?

Last, I dont have a "tilt" to the panels and I wonder if there was the potential to put in an air escape valve to prevent air entrapment from preventing the array from filling properly?

Thanks all.

 

[Isaac-1]

The issue in this thread is constant bubbles from a VRV, not just at start up. Panels need to be tilted to keep water and air from being trapped in them, your installer should have done this. It does not take much tilt (1 inch in 8-10 feet is usually enough)