Feedwater Heater v. Superheater

[Subdeacon Joe]

What is the difference between a feedwater heater, and a super heater?;
In a feedwater heater, you're preheating the feedwaterbefore it's boiled to make steam. With a superheater element, you're heating the steam that's already been made. Feed water heater is the big barrel-y boil on top of the smokebox, it heats water from the tender before it gets put into the boiler so that heat isn’t lost trying to heat that cold water up to temp. Superheatersare steam pipes that run INSIDE the fire-tubes (flues) and the steam that is going to the cylinders gets heated way above 100c (what it would usually be) making it more efficient.
Given the benefits of a feedwater heater the obvious question is: "Why didn't all steam locomotive have them?" The answer is: Because railroads had to weigh the cost of higher maintenance against the price of fuel. Sometimes, the cost of fuel was simply cheaper than the cost to maintain them.
There are two main types of feedwaterheaters: open and closed
Feedwater is always preheated equiped with a live steam valve, the purose of wich is to automatically heat the feedwater with live steam from the boiler, when exhaust steam is not available .- this prevents cold water from entering the boiler when exhaust steam is not available
 

 

[Forty Rod SASS 3935]

Those big Berks were some of the most beautiful and elegant locos ever put on tracks.  Thanks, Joe.