How do I bleed air out of solar panels after flushing the heater?

[HomeRepairGuy]

What's the proper procedure for bleeding air out of the solar panels after the flushing the water heater?

We live in an area that never freezes. Our solar water heater system sends potable water from the 80 gallon electric heater up to two solar panels on the roof and back down to the water heater using a small temperature difference controlled pump. The system has been installed for about 2 years and I want to flush the water heater by draining it completely and then pulsing the cold water inlet, drain, repeat until clear.

Our two solar panels are hooked up as follows:

Heater>--->Circulation pump>--->Ball valve>--->hose bib>----/roof/--->T fitting>---> TO BOTTOM OF EACH SOLAR PANEL == FROM TOP OF EACH SOLAR PANEL>--->T fitting>---/roof/--->Hose bib>--->Ball valve>--->Heater

NOTES:
- Cold water from heater goes up through the roof where there is a "T" fitting on the roof and the two outlets feed the bottom "left" of the two solar panels.
- There are hot water outlets at the top "right" of each solar panel and they both feed a "T" fitting with the common outlet going down to the heater.
- There is only one pressure relief valve at the top "left" of one solar panel.

So again, what's the proper procedure for bleeding air out of the solar panels after flushing the water heater is complete?

[Mike90250]

At the high point in the system, there has to be a bleed valve (air purge), and you would likely need 2, one for each heater panel.

Generally, to flush gunk out of the system, you would stop the circulation pump in the evening as you go to bed, and then get up early before anyone else, and open the drain valve on the water heater main tank, and all the settled out crud will be flushed out. Hook a garden hose to the flush valve, and drain the stuff to the gutter, don't cook your lawn with hot water and sludge.

Dangers:
crud can block the crappy hose bib type valve, and you get no flush. Removing the crappy hose bib and replacing with a brass nipple and full flow ball valve, will let large chunks of crud out.

Total drain and flush will leave several air pockets that will take a couple days to bleed out sometimes.

[HomeRepairGuy]

At the high point in the system, there has to be a bleed valve (air purge), and you would likely need 2, one for each heater panel.

Generally, to flush gunk out of the system, you would stop the circulation pump in the evening as you go to bed, and then get up early before anyone else, and open the drain valve on the water heater main tank, and all the settled out crud will be flushed out. Hook a garden hose to the flush valve, and drain the stuff to the gutter, don't cook your lawn with hot water and sludge.

Dangers:
crud can block the crappy hose bib type valve, and you get no flush. Removing the crappy hose bib and replacing with a brass nipple and full flow ball valve, will let large chunks of crud out.

Total drain and flush will leave several air pockets that will take a couple days to bleed out sometimes.

There's only one pressure relief valve at the top left of only one solar panel. I assume there's a way to bleed air out of that panel using it. But how to bleed air out of the other panel is what mystifies me. The installer must have done it, but how?

Replacing the hose bib drain with a full flow ball valve really sounds like an excellent idea. The problem with our installation is that the installer removed the hose bib at the bottom and installed a "T" fitting in it's place. Hot water from the solar panels on the roof go into one side of the T fitting and the hose bib is installed on the other side of that fitting. So it looks like this:

fm solar panels on roof
|
|
v
||
==water heater
||
hose bib

Water draining out from the water heater has to make a 90 degree turn to exit the hose bib (or ball valve) when draining. Would replacing the hose bib with a ball valve still be worthwhile in our configuration?

There's another thread in this forum where the poster asks about both connections to the water heater being made at the bottom of the tank which is how our set up is. I'll be responding in that thread shortly.

Thanks for the help,
HRG