Bubbles in returns w/ Solar.

[pvstansel]

Replaced old 2HP with Pentair VSP. FAFCO Solar. As I start to use solar, getting bubbles thru returns. The amount of bubbles is proportional to the RPM of the VSP. (2200RPM = lots of air, 2300 = less air, 2400RPM and above - champaign bubbles. At 2400RPM PSI is 16. I Replaced VRV. Cleaned DE filter, and also went ahead and replaced o-rings in all my jandy valves. 2 story home (perhaps taller than most with higher ceilings).

I have 2 questions.

1. Do I even have a problem? (I've been told that I should be able to run 2200RPM on my setup and run solar just fine. My goal here is to run at lowest RPM to save electricity).
2. Can someone provide some additional guidance on relocating the VRV. Right now, my (new one) is installed on the highest point on the highest panel (peak of roofline). Is it as simple as relocating the VRV to one of the next lower panels?

Thanks in advance.

 

[jblizzle]

Does not sound like a problem, the low speed was not closing the VRV. Realize that solar heating is most efficient at higher flow rates though.

You can lower the VRV. I have mine right at the inlet to the panels or you can go down by the equipment, but that can have it's own problems.

 

[Isaac-1]

When VRV valves are installed at the highest point it is possible for them open when they see negative pressure due to the siphon effect of the returning water if the gravity flow rate in the pipe is faster than the supply side flow rate. This is something we seem to be seeing more and more of, I suspect mostly due to people with variable speed pumps trying to run them at too low of speed, but it may also be due to over sized plumbing with little or no back pressure on the return line as the larger pipes have higher gravity flow volumes. A simple solution to this is to move the VRV valve down to the feed side of the panel, the slight additional pressure here is usually enough so that either the VRV will close, or the additional head seen relative to the VRV will cause the pump to stall out and water not get to the top of the panel (head of the system does not significantly change, and dynamic head probably actually improves due to the siphon effect working). Moving the VRV valve does allow the top of the panels to see negative pressure, which is generally bad for them, but it is only slight negative pressure, much less than they would see if the VRV were moved all the back back down to ground level on the feed side.

Ike

 

[pvstansel]

Ike,
I followed your advice (move VRV to feed side and lower elevation (6ft lower)) .... and my bubble problem seems to be fixed. No bubbles running at 2200RPM! I'll keep dialing it in but I believe you solved my problem.

thank you !
Paul