Heat exchanger vs. pencil zinc. Assumptions and questions

[Christian Williams]

I wonder if the installer brazed that end cap on. Heat exchangers always seem to open up for cleaning and getting junk out.

 

[Prairie Schooner]

I wonder if the installer brazed that end cap on. Heat exchangers always seem to open up for cleaning and getting junk out.

Possible. The other end was a gasketed cap attached with a machine screw. It's all unfolding mystery to me.