I was noticing on Rheem furnaces while looking through data on their web pages that their heat exchangers are tubular steel, while most other manufacturers used stamped steel heat exchangers, where it looks like they take two stamped metal halves and either weld or clamp them together. The Rheem tubular steel heat exchangers look much more durable, but they don't look like they would transfer as much heat. What is the "real world" performance of these furnaces as far as durability goes? I am really liking what I see with Rheem/RUUD and am thinking of their equipment when I upgrade over the "big two" Carrier and Trane.
Also, I saw where one manufacturer (I think was either Lennox or Trane) said that their heat exchangers are not welded to reduce thermal shock and minimize cracking. Is this true with welded heat exchangers?