A system for heating a door guide area includes: a first and second conduit for channeling a flow of heated air; a heater fluidly connected to the first conduit and configured to provide air to the first and second conduits; first and second openings providing fluid communication between the first and second conduits to allow the air to circulate through the first and second conduits; a heat transfer wall part of the second conduit, to transfer heat from the flow of heated air in the second direction to a space outside of the second conduit that is defined, in part, by the heat transfer wall; and two side supports connected to the heat transfer wall, the side supports located opposing each other and dimensioned and located along with the heat transfer wall to form three sides to encompass a portion of a roll-up door.