An apparatus for connecting a heater to a grain bin aeration fan featuresa multi-piece adapter device having a connection adapter with inlets forreceivingflexible ducts from a heater. The connection adapter can be used on its own todirectlyinterface with a grain bin aeration fan of a first size, or can be used incombination witha cooperative sizing adapter to adjust an effective outlet size of the adapterto better fita grain bin aeration fan of a different second size. An ambient air intake intheconnection adapter entrains ambient air into the heated air stream.
