There is very little water in the exhaust from burning anthracite, there is very little water in coal.
Burning oil, NG and propane does create water, but not burning anthracite..
Anthracite is breaking carbon bonds and joining the carbon it with oxygen in the air, creating CO and CO2.
Burning oil, NG and propane which are Hydrocarbons, you also are breaking Hydrogen to carbon bonds and joining the hydrogen with oxygen, which makes water: H2O..
So you can safely run cooler temps with burning anthracite.. there is a little water in the coal itself, but a very small percentage, unlike Bit and sub-Bit coals which have a lot of water in the coal, depending the the mine and vein of coal..
Condensing of exhaust on less than 140* surfaces is a carryover from burning hydrocarbons, it is really not an issue with burning anthracite.
Correct me if I'm wrong, but this was explained to me many years ago. It make sense to me..