Old Water Heater or Gravity Fed Hydronic?

SENorthEast1895er

This is in my attic and i’m wondering if it’s an old water heater (where they ever put in attics?) or a remnant from when my system was switched away from gravity fed.

hot_rod

with a site glass it would more then likely be an expansion vessel.

SENorthEast1895er

Interesting. Why in the attic? Trying to figure out if I used to be gravity-fed.

hot_rod

The highest place in the system, it added the pressure to the system and served as the expansion "space"

mattmia2

The system was open to the atmosphere at that tank. If it was lower in the system the water would come out.