HVAC Jargon Demystified

Goodway‘s Just Venting is offered as a service aimed focused on the needs of building owners, operators and managers. It’s been designed to help you operate the most efficient, cost-effective HVAC systems possible. While we do address non-HVAC subjects such as lighting or pressure washers or vacuum cleaners, we do tend to emphasize HVAC and HVAC equipment. And we realize that sometimes we can get a little carried away with technical “stuff”.  So, for those of you whose expertise lies in other areas, here are a few HVAC-related terms and expressions you may encounter in your research:

BTU – British Thermal Unit

A British Thermal Unit (also called BTU/hour) is a measurement of energy. It equals the amount of energy you would need if you wanted to raise the temperature of one pound of water by one degree. In the HVAC business, if you had 12,000 BTUs, you would have a ton of air conditioning capacity. This is the amount of heat you would need to melt one short ton (2000 pounds) of ice in a 24-hour period. A BTU is equal, according to the Columbia On-Line Encyclopedia, to 251.9 calories. A pound of good-quality coal should generate 14-15,000 BTUs and a pound of gasoline (about 1/6 of agallon should generate 19,000 or so BTUs.

Boiling and Condensation Points

The boiling point of a liquid is the point at which, if you add any extra heat, it will turn into a gas. The condensation point is just the opposite –the point at which, if you remove any heat, a gas will change into a liquid. For water, for example, the boiling point is 212 degrees F (100 degrees C). Boiling points change with pressure. The lower the pressure, the lower the boiling point of a liquid. Conversely, boiling point goes up as pressure goes up.

Not all boiling points are that high. Ammonia, for example, boils at 28 degrees F (-33.34 degrees C). This property makes ammonia a potential replacement for chlorofluorocarbon (CFC) refrigerants, which are falling out of favor because of their potential to damage the environment.

Humidity and Relative Humidity

Humidity is the amount of water vapor in the air. Relative humidity is the percentage of moisture in the air compared to the maximum amount of moisture the air can hold at a given temperature. At 33% relative humidity, the air is saturated to about a third of its capacity for that temperature. The higher the temperature, the greater the amount of moisture air can hold.

According to the Canadian Centre for Occupational Health and Safety, people are most comfortable at a relative humidity of around 50%. Below that level mucous membranes start to dry out and skin rashes become more common. Relative humidity much above 50% can contribute to the development and growth of mold and fungi, and make the air seem stuffy.

Higher humidity makes people feel warmer because the moisture in the air makes it harder for their sweat to evaporate and cool their skin. Lower humidity promotes evaporation of sweat, making people feel cooler.

As HVAC goes more and more high tech, the business becomes filled with more acronyms, terms and jargon. We’ll be posting more of these soon so, if there’s anything that you’d like to learn more about, please comment back to this post and let us know.

Rich Silverman
Goodway Blogging Team

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