Everything You Need to Know About BTUs

Everything You Need to Know About BTUsMaking sense of all the terminology used in reference to a home heating system isn’t easy. One term you’ve probably heard many times is “BTU.” If you’d like to know exactly what it means and the role it plays when you’re choosing a furnace or heat pump, here’s a brief primer that can help clarify the topic.

BTUs Explained

BTU is short for “British thermal unit,” but it’s not a term related to heating systems in the U.K. Here in the U.S., it’s used as a measurement of heat energy, with one BTU being the amount of energy used to heat a pound of water by one degree. To help you gauge how much energy that is, one BTU is produced when you completely burn a 4-inch wooden match stick.

Home Heating Equipment and BTUs

When you’re comparing heating equipment like furnaces and heat pumps, you’ll probably notice that they have two BTUs listed. The first number is the input, which is the amount of fuel the unit burns. The second number is the output, or the usable heat the unit generates. When you’re looking at specific models, the input number tells you the capacity or size, while the output number tells you how efficiently they operate.

How Many BTUs Should Your Heating Equipment Have?

Furnaces and heat pumps are available with input BTUs ranging from 40,000 up to 100,000. When you’re selecting new equipment, it’s may seem logical that a bigger capacity is better, but that’s not true. Equipment will short cycle if it’s oversized for your living space, making it too hot when it cycles on and too chilly when it cycles off.

To size equipment correctly for your home, an HVAC contractor needs to do a Manual J calculation based on specific conditions like your:

  • Square footage.
  • Size/type of windows.
  • Amount/type of insulation.
  • Ductwork design.
  • Local climate.

With the equipment capacity calculated, a pro can recommend specific models based on their efficiency ratings.

For expert advice about BTU and efficiency ratings of heating equipment for your San Diego home, contact us at Sherlock Heating & Air Conditioning.
Our goal is to help educate our customers in the greater San Diego and San Marcos, California area about energy and home comfort issues (specific to HVAC systems).

Credit/Copyright Attribution: “geralt/Pixabay”

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2 Comments

  • Thanks for the information. This will come in handy when explaining to my customers what btu is all about.

    Reply
  • This is some really good information about heating contractors. I like that you pointed out that you should pay attention to a number of inputs the heater has. That wouldn’t have been a thing I would have never thought about before.

    Reply

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