Can you comment on how the different feedwater heaters compared in actual service (Worthington, Elesco, Coffin)? I'm vaguely familiar with the difference in open vs. closed systems but have no clue if there were real performance differences.

I guess the real test would be comparing performance between two engines of the same class equipped with different manufacturer's systems. I'll start digging...

Also, how did residual valve oil in open systems impact the boiler? I'd think perhaps that would result in a bit of extra deposits in the boiler that are taken care of by regular boiler washes, but again no real clue.

Thanks in advance.