David,Hi,I have the SF150 that LS Farms is talking about.I paid 500 for mine,it is a 1982 model,except for rust it looked barely used.I had been burning wood in my shop.30X32X10 pole barn,1 inch of foam for insulation,the switch to this SF150 is one of the better desisions I have made,the fire last fo a easy 12hours,16 if I am lazy.I have the brochure from 1982,it covers the Sf150 ,SF250,and the SF350.It appears as Harman only makes the SF 250 now.I installed 12 " risers to my legs of the stove so I did not have to bend over so far.
I would do it again in a heart beat,I have a Harman top loader wood stove in the house,I would like to switch that to a coal stove as well.
As LS Farms says,pull the plate off front on top and look for ash,mine had at least 2"s of ash,it may have been from the Bituminous I was burning,I burnt it for the first part of this season as well.I pulled inspection cover after I finished with Bituminous,sure enough,thee was another 2" of ash,now at the end of this season I will inspect again,then I will know.
This stove will burn anything you put in it,Mine(before EPA)is called a "Duel Fuel"unit,wood is QUICK and hot!!!,coal (antrachite) last like forever,30 degrees outside calls for 1.2 turns open on bottom ka nob,0 degrees calls for 2 turns, I am sure yours will vary acording to conditions.I guess I will close with,I can not say enough nice things about this stove,eh?