An electric heater is used to heat a room of volume 62m3. Air is brought into the room at 5oC and is completely replaced twice per hour. Heat loss through the walls amounts to approximately 850kcal/h. If the air is to be maintained at 20oC, what minimum wattage must the heater have? (The specific heat of air is about 0.17 kcal/kg ∙ Co).