Heating Help

Brown DrainBack Water

Solar Wizards,

My System:
4 SunEarth  4' x 10' collectors
Stainless Plate Heat Exchanger (radiant); Quad Rod Heat Exchanger (DHW)
15-20 Gallon Drain-back Tank
Unpressurized Drain-back Setup
Closed Loop

A few months after firing up my system about 2-3 years ago, I began noticing just a slight browning of the water visible through the sight glass outside my drain-back tank.  It presently looks like what's shown in the attached photo.

I'm interested in hearing your thoughts on how to proceed and how much of a concern this "browning" is.


Thanks,

Martin Romero

my guess

would be that the system has a pump with a cast iron body. If so that is where the red color is coming from. A bit of color actually makes it easier to see the level in the sight glass.

I prefer a pressurized drainback, but as long as it is a true closed loop, you should not see a lot more dis-color.

Browning water

Thanks Hot Rod,

I was certain the pump was brass, but I will double check. No real concern about heat transfer?

Most likely a steel tank

Martin,

My first guess was also a cast iron pump. That tank could be steel, however. Do you have the brand name and model for it? Even if it is a glass-lined steel tank, a little bit of rusting at the fittings would be normal.

BTW if it is a true unpressurized drainback system, that means it must be vented somewhere. A vented system usually causes a cast iron pump to fail prematurely. If it's truly a closed loop system, it will create some pressure when the air and water gets hot.