I have an Energy King 480
I have been heating my old farm house with it for 5 years and burning coal in it steady since the begining of the heating season and for a month last year.
You cant find a better built or more bullet proof furnace in my opinion.
You wont ever be cold with this unit.
No problem burning coal without forced draft at all.
The 480 is built to last .i think it weighs in at near 700 lbs.
I called about spare grates once..They asked me how old the unit was .I said almost new.
Then they said you shouldnt need any for at least 20 years! They show no signs of wear or warpage anfd get a hell of a work out when shaking down.
This unit is same as the ones 20 years older than it. I like it when a company has a good unit and doesnt cheapen it to match lower priced units.
I say you wont go wrong with an Energy King.
If you want to know something call them.They actually answer the phone!!