I'm going to have to disagree with the premise that water released during combustion isn't an issue with anthracite. It certainly is true that anthracite has a high proportion of carbon, but it also has a significant amount of hydrogen, which forms water during combustion. An approximate chemical formula for anthracite of C240H90O4NS is shown at page 3 of http://www.purdue.edu/discoverypark/ene ... -Oct08.pdf
. On an "as received" basis, anthracite also typically has a moisture content of up to 10 percent or more - see "Specifications" tab at http://jeddocoal.com/
. That's why there are different ratings for "as received" vs. "dry basis". I wouldn't assume that moisture issues can be assumed to be minor with a coal boiler. If anything, the combination of moisture and fly ash tends to be pretty corrosive, and a good reason to maintain a low limit that inhibits condensation.