Heat exchanger coil

In a heat pump, an outdoor heat exchanger, said outdoor heat exchanger comprising coil means for conducting therethrough a heat exchange medium, said coil means defining a substantially enclosed interior chamber into and upwardly through which air is adapted to flow, said coil means including relatively spaced coil portions between which air passes from said interior chamber to the exterior thereof, said coil means having a generally open lower end portion in fluid communication with said interior chamber, heat-generating means disposed generally contiguous and below said coil means for introducing a flame substantially entirely into said interior chamber through said open lower end portion whereby the heat of the flame is absorbed by the heat exchange medium during the passage of the heat into the interior chamber and through the spaced coil portions, means for closing an upper end portion of said interior chamber to prevent heat from flowing therethrough whereby essentially all of the heat introduced into the interior chamber is absorbed during its passage therethrough and to the exterior of said coil means through said spaced coil portions, and fan means for drawing a limited amount of air from the exterior of said coil means to withdraw air from said interior chamber thereby creating a negative pressure within said interior chamber for assuring air flow from said interior chamber to the exterior thereof through said spaced coil portions.