Determine the age of old furnace

I need to determine the age of a furnace. furnace found in a crawl space of a house built in 1920. I can’t figure out in what year it was made.
It’s a model of Sears, Roebuck & Co. It has a model number: 867 1401 (867 is fixed and 1401 is in the fill-in field). No serial number or any other number.
Would appreciate your help. Thanks

You can estimate the age of stuff you find by researching their history.
As far as I know the only furnaces available in 1920 were gravity types and space heaters, ie no fans.
Furnaces shrink in size and grow in complexity as they get newer.
1950’s forced air furnaces are typically made from heavy gage welded metal and are very large for their BTU output rating.
60’s and 70’s forced air furnaces were tinny, fans were usually belt driven
80’s furnaces tend to have more complexity and smaller than earlier furnaces, fans more likely direct driven, BTU input/output rating (not AFUE) were close to or at 80%. Higher efficiency furnaces have smaller vents, 5 to 7 inches for 60’s 70’s to 4 inch in mid 80’s for similar outputs.
90’s furnaces are AFUE rated.
High efficiency (90%+) AFUE start to appear in the 1990’s

Good stuff Erik.
How old are ya? …LOL! :smiley:

Old enough to have had my hands on all of the above :slight_smile: