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What is a BTU Unit?

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The definition of a BTU unit is one of the most important things to know when you’re shopping for a heating or cooling system. BTU stands for British Thermal Unit, and it’s the basic measure of thermal energy. Here’s how it works: one BTU is the amount of energy needed to heat one pound of water one degree Fahrenheit, measured at its heaviest point. Another way of looking at it is if you placed 16 ounces of water at 59°F in a pan on your stovetop and turned on the gas burner, it would take one BTU to raise the temperature of the water to 60°F. As you add more BTUs from the gas flame, the water will eventually reach the boiling point of 212°F.

This formula works in reverse for cooling power. The BTU rating of an air conditioning system refers to the amount of thermal energy removed from an area. The higher the BTU output, the more powerful the heating or cooling system.

A good point to remember when shopping for heating or cooling systems is that even the smallest window-mounted air conditioner or space heater can produce thousands of BTUs. Larger and more expensive systems should provide significantly higher BTUs than smaller ones. The BTU number will give you a good point of comparison when you’re deciding between two units that have a similar sticker price.

Remember the BTU unit

When you’re shopping for an air conditioning system you should try to estimate the actual cooling capacity you’ll need. For example, a 2,000 square foot home (with standard ceilings) may require a cooling system of 30,000 BTU capacities. However, if you have a lot of windows that let the sun in, or some other unusual exposure to sun, that can add 10 percent (3,000 BTU). You also need to factor in another 600 BTU for each occupant. If there are four people, for example, that would add another 2,400 BTU, for a total of 35,400 BTU. This is the number you need to look for in a new air conditioning system.

Remember, though, that your air conditioning requirements can also be affected by how well insulated your house is. If your house is sealed up tight and does not leak air through cracks, windows or doors, it will require much less cooling capacity. Today’s energy efficient appliances also further reduce the BTU requirements.

Getting an accurate determination of your home’s cooling needs may require a professional evaluation. The money you’ll pay for an evaluation like this is worth it, however, in the energy savings you’ll have from installing an air conditioning system with the correct BTU rating for your home.

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