What Exactly is a BTU?

August 9th, 2019

BTU Guage

No, it’s not the latest text abbreviation (unless you really love chatting about HVAC).

As Orange County’s preeminent heating and air conditioning company, we treat our customers like family – always taking the time to explain things thoroughly and completely. 

For instance, the BTU – or “British Thermal Unit” – is a foundational principle in our line of work, and we often refer to the BTU rating when deciding upon the best heater and air conditioner for a particular space. Be sure to read on to learn more about this concept – and remember to give us a call if you have any further questions or are considering an upgrade or service to your current system. 

The Science Behind BTU

A BTU is a unit of thermal energy that measures the amount of fuel needed to heat one pound of water (at sea level) one degree Fahrenheit. This measurement tool has been in place since the 1800s when it was relied upon to configure the amount of energy needed to propel steam engines. Since that time, the BTU has remained the standard unit of thermodynamic measurement for engineers worldwide – and is applicable to calculations involving everything from large-scale boiler plants to residential heating and air conditioning units. 

Understanding the BTU Rating

When it comes to the BTU rating of an air conditioner, the rating actually measures the amount of heat the unit can remove from the air per hour. For example, a small portable air conditioner will tout a rating of 8,000 – 12,000 BTU/hour, whereas a large window unit can remove up to 36,000 BTU/hour. 

For heating units, there are two types of BTU ratings: BTU input and BTU output. A BTU input rating refers to the volume of fuel the unit can convert per hour into heat for the home. This rating is also impacted by the loss of some fuel during the conversion process, known as “inefficiency.” The BTU output rating for a heater, therefore, is measured by its intake BTU multiplied by its efficiency percentage, divided by 100. The more efficient the heater, the lower this number should be – however, no single unit is 100 percent efficient. 

Why BTU Rating Matters

As our knowledgeable technicians will explain, the BTU rating helps to inform consumers’ decisions when choosing a new air conditioning or heating unit for their home. One of the most important aspects of selecting a unit is determining the appropriate size for the square footage involved.

As part of our client-centered approach, we ensure each customer selects the appropriate size unit for their space – nothing too big or too small. When a heating or cooling unit is too large, this can result in higher energy costs and unnecessary expenses. Also, we help customers select the efficiency rating to meet their needs, as this also varies from 60 to 95 percent. When it comes to efficiency ratings, the most efficient unit ratings are associated with electric units, while wood or pellet-burning units are considered the least efficient. 

Rest assured: By working with Home Comfort USA, you’ll be in great hands. 

Read More About Air Conditioning