I've been assigned responsibility for the closed loop treatment in a number of city of Phoenix facilities, and I normally use NuCalgon's TyIon B-20 nitrite/borax loop treatment. I like the fact that it has a (pink) dye added so you can tell the difference between condensation and a leak.
A few weeks ago I checked the loop at a police precinct that has a dozen water-source heat pumps, mostly three or four tons each. My supervisor requests that I keep the nitrite around 2000 ppm in loops that are assisted by a boiler.
I found the loop water foamy last month, and it smelled weird. TDS was reasonable, 4700 (city water at 1100). With a TDS that high, I assumed that the nitrite level would be good. It wasn't; it was at 360 ppm.
I'm guessing that the foam was caused by a pinhole leak in one of the (R-22) heat pumps. It's not cold enough here that they would notice a heat pump not working in the winter, so we haven't gotten any service calls yet.
I drained the loop, used some NuCalgon system cleaner, drained and flushed it again. TDS is pegged (over 5K) and nitrite is back to a comfortable 1960. But I think I'm seeing tiny bubbles in it again.
My supervisor doesn’t think there’s enough refrigerant in one of the heat pumps to cause this much foam and bubbles. The largest one holds 6˝ lbs. I've never seen foam or bubbles in a loop before, and wonder if anyone here has any other ideas or maybe experienced this before. My guess is that one of the units has a tiny leak in the coil, and that some kind of weird chemical reaction happened with the nitrite.
Thanks in advance.
Vicki in Phoenix