Help troubleshooting bubbles/gurgling pipes


Well-known member
Feb 24, 2015
Davis, CA
So, recently, we’ve started noticing gurgling in our rooftop solar return line.

I’ve googled a bit and think I have the problem narrowed down, but I was hoping for a second opinion.
The gurgling is definitely in the solar return line (it shakes, even). There’s some air in the pump basket, but not a ton (the water gets up to maybe 1/2” from the clear lid).

I tried snaking the line from the skimmer to the pump, in case of a clog, but found nothing. I also checked the impeller for clogging/debris. Same there.

Opening the valve on the solar return, the pressure is pretty low.

Based on my research, I’m leaning toward a bad vacuum relief valve (it’s the kind that looks like it has a tight-packed bundle of wire on it), but I’d appreciate any advice.


TFP Expert
LifeTime Supporter
May 3, 2007
Pleasanton, CA
Yes, it could be the VRV but it could also be a few other things such as a suction side leak.

If you have air in the pump basket, there may be an air leak somewhere. Probably in the pump lid gasket. Any air in the pump basket will eventually make it's way to the solar panels so I would check that first before replacing the VRV. Try lubing the pump lid gasket and see if the air bubble goes away.

Also, has the filter pressure changed at all? A dirty filter can reduce the pressure on the VRV and it will open allowing air into the solar plumbing. Worth trying to clean the filter.