Expansion Tank

• Air side up in this mounting - [1]
• Some places say upside down matters - [2]. Supplyhouse says it doesn't matter [3].
• IT seems it does matter - process connection at top, so that trapped air bubbles can float up and out. [4]. If it's on the side, air can get trapped inside. This makes sense to me. Also - can corrode if it's on the side, or put more stress on the bladder [5].
• Summary: always think of how the air escapes a pressure or expansion tank