Here are a few excerpts from the undated article in Rodale's New Shelter.
"I've got to stop heating with oil. That was a decision I made two and a half years ago. But what were the alternatives? Not solar, unfortunately. Our 25-year-old house offered little opportunity for solar retrofitting. Eventually I made up my mind to go with coal.
True, coal is not ecologically perfect. It isn't renewable, for one thing. And it's burning adds carbon dioxide to the atmosphere, contributing to a possible global "greenhouse effect." But it's better than oil, I thought. It's much cheaper, that's for sure."
"Our heating cost is now about half what it used to be. We keep the thermostat set where we want it, no longer feeling that our personal comfort in winter directly affects the U.S. balance of payments. Ardie feels that coal is actually a better fuel than oil. "It keeps the basement warmer," she says. "It gets rid of the dampness. It's warm, warm, warm."
"When summer comes and the fire is out, I feel as if a faithful pet has gone into hibernation. My oil burner never made me feel that way."
From the article, written in the mid 80s, I sense that he bought a recycled unit, true to his nature, because he opens "the little round observation door", and peek(s) at the glowing coals....