Salesman sample of a gravity hot air furnace.

This is a salesman model of a Jewel #2652 Gravity Hot Air Furnace that was Manufactured by Detroit Stove Works. The model is 11-1/2" High with the Heat Exchanger at 7-1/2" in Diameter. The metal looks like cast Pewter. The doors on the model open and some of the parts operate to show how the actual furnace would work. I was wondering if this model has any value or would anyone know where I might find more information on this item. This piece looks like real American Manufacturing History. I think most of these Gravity Furnaces were sold during 1880 – 1920. I would estimate the age of this salesman model to be around 1900 – 1920.