To determine the correct size PowerHeat infrared heater for a room, measure the room in square feet, calculate the number of watts the room requires, convert the watts to British thermal units and adjust for variables particular to that room. With this information, choosing an appropriate heater is straightforward.
Measuring a room's size in square feet requires measuring the room's length and width, and then multiplying the values. For instance, a room that is 10 feet long by 12 feet wide has an area of 120 square feet.
Every square foot of floor area in a well-insulated room requires 10 watts of energy for effective heating, so the 120-foot room requires 1,200 watts of energy from a PowerHeat infrared heater. Convert the wattage to BTUs by multiplying the wattage value by 3.41, as there are 3.41 BTUs in every watt. Therefore, the 120-foot room that needs 1,200 watts requires 4,092 BTUs.
Not every room has the same heating needs. A room in the center of a well-insulated house, with plaster walls and no windows, does not require as much heating energy as a poorly-insulated room with many windows along an exterior wall. Other factors, like the ceiling height of the room, how often people enter and exit the room, and whether the room has carpet, tile or hardwood floors, also impact the amount of heating BTUs that the room requires.