My boiler has an indirect tank which has an automatic air vent and a second automatic air vent on a tiny tank between the diverter valve and the expansion tank. Both air valves have precipitation on them and are moist most of the time. The system is losing water treatment chemical solution at about a liter every quarter. For years it did not loose any fluid. I changed the air vent on the indirect tank about a year ago and the new vent is nasty looking now. What gives?
Is the concentration of water treatment chemical too high? How can I test the concentration?
The pipe is mostly copper and the boiler is aluminum. The convectors are a mix of steel and copper. Therefore, the water treatment chemical has corrosion inhibitor properties.
The diverter valve gunked up last year which made it stick, and I had to drain the system to replace the core. I could have just cleaned the core as there was no damage to it.
Parts marked number 11 are the air valves. The drawing is fairly accurate. The DWH supply and return may be reversed if I remember correctly.
Since the boiler is in a cabinet, it would be difficult to move the air valve on the top right. It just clears the inside of the cabinet. It would be possible but difficult to install a right angle valve in place of the one on the top right.
However, the boiler is European and may have straight threads which I find very difficult to seal compared to NPT tapered threads.