A grain dying system for a grain bin that includes a heating unit arranged in a proximity of the grain bin and ducting connected at one end to the heating unit and another end to a grain drying adaptor. The grain drying adaptor is connected at one end to the ducting and at another end to a fain unit of an aeration system for the grain bin. The fan unit is attached to the grain drying adaptor. The grain drying adaptor is configured to introduce a blend of heated air from the heating unit and ambient air from outside the grain drying adaptor into the aeration system of the grain bin.