According to the Physics and Astronomy site at U.C. Irvine, one BTU is equivalent to 1055 joules and kilojoules/hr are converted to BTU/hr by dividing the kJ/hr by 1.055. Both kJ and BTU are units of energy so it is only possible to convert from kJ/hr to BTU/hr rather than from kJ/hr to BTU.
Although kJ and BTU are units of energy, they are derived in very different ways. Kilojoules come from Joules, which are equal to the amount of mechanical work performed by one Newton of force acting over a meter of length. This unit of mechanical energy can also be used to measure other types of energy (including heat).
BTUs, or British Thermal Units, are units of energy that are defined based on measurements of heat. These are not metric units, as they relate to the Fahrenheit temperature scale. One BTU is enough heat to raise the temperature of a pound of water by one degree Fahrenheit. For contrast, a calorie is enough heat to raise the temperature of a gram of water by one degree Celsius.
One calorie is also equivalent to 4.184 J. As a result, it is also possible to convert between BTUs and calories. One BTU is equivalent to 252.2 calories.