My father purchased a simple plate steel box stove back in the late ‘70’s. All steel, no glass. It was about 2’ x 3’ x 4’ with a fire brick bottom, and water piping on the sides. It stood on four 1” pipe legs. On the back were the inlet, outlet, and circulation loops. We had a basic 1/3 horse circulator regulated by an aquastat. It exchanged water with the oil-fired boiler, and him being a carpenter, we usually had plenty of wood. I don’t ever recall having a problem with the chimney, and it was serviced seasonally. If anyone knows where I could find such a box stove these days, I would like to get another. It lasted about 23 years before we had to let it go due to eventual metal fatigue, and failure of the water piping