Abstract: A fuel oil supply system for providing fuel oil to a heater in a building includes a storage tank, a gravity feed supply line running from the fuel oil tank to the building, a fuel oil heater in the building receiving the fuel oil from the supply line, and a canister filter connected in the supply line. A means for heating the canister filter includes a heater enclosure defining a filter cavity which is sized to receive the canister filter. The heater enclosure includes a substantial cylindrical lower portion and a substantial cylindrical cap portion which interfit to enclose the filter. The cap portion defines openings for passage of the supply line therethrough and the lower portion and the cap portion are joined by set screws. An electrical heater in the filter cavity comprising a light bulb positioned below the bottom of the filter provides a source of heat to the canister filter. Power is supplied to the light bulb by a power cord including a thermostat.