Consumer Considerations and Home Efficiency Part 1
There are always misunderstandings when the conversation of air conditioning comes up. I want to clear up some misconceptions and give some basic understanding of how your HVAC system accomplishes raising and lowering temperature in your home. I will also include other factors that will help you “feel” more comfortable without lowering the thermostat. Who knows, you might even be able to apply something you learn here to your next trivia competition.
Air conditioning is literally “Conditioning” the air in the environment of your home, office, or structure. There are times when temperature needs to increase for comfort. There may be times temperature needs to increase to help remove certain humidity. Most of the time we think of lowering temperature for comfort and humidity—especially in Southeast Texas. We achieve these changes in our air-conditioned space by moving heat around. That sounds weird, I know, but the truth is our science class comes into play as we manipulate our personal environment to meet our comfort standards.
As a reminder, lets begin with the fact that heat always moves toward cold. Thinking this way, cold is the absence of heat like an empty glass is the absence of liquid, so the volume for heat exists but isn’t filled up—if heat is therefore present it wants to fill the space that is cold. Now once our space is hot, or filled with heat, we want to remove that heat to make the space more to our liking. This is the premise of air conditioning. We must absorb heat in some medium and then disperse that heat into another medium does not have any effect on our comfort.
Enter refrigerant. Refrigerant is a liquid that absorbs heat and changes to a gaseous state, that is then moved through tubing to the exterior of our house (in our scenario) where it is pressurized and releases the heat outdoors. (Think about this: liquid needs heat so that its atoms move faster and further away from each other. Then that gas that is created by absorbing heat is pushed together under pressure—compression—so it has to get rid of heat and transition back into a liquid.)
Water can be a refrigerant, but it is hard to efficiently change its states back and forth. When applied as a direct refrigerant in the mid-20th Century, coupled with a fan, it cooled the body. A better personal refrigerant is rubbing alcohol. When wiped on the skin, it nearly instantly changes to a vapor and removes the heat it absorbed from our skin into the air. One of the most awe-inspiring refrigerants (also very dangerous) is liquid nitrogen. It transforms to a gas at such a low temperature, that when poured as a liquid, it absorbs all available heat leaving the object it touches completely frozen in less than seconds. We can discuss more about refrigerants in a later episode.
The “other” conditioning that takes place is that we remove moisture from the air. This moisture is called humidity. High humidity in the air causes water to evaporate slowly. Water (perspiration) on the skin is our natural God-given cooling system. Without going deeply into our biology, suffice it to say that if your body begins to overheat, your blood is forced into the vessels closest your skin where your perspiration absorbs the heat from the blood and then changes to vapor (evaporates) taking the heat away from your body. When the humidity in your immediate environment is very high, it takes longer than ideal to remove the heat you are feeling. When, on the other hand, humidity nearby is low, your perspiration can quickly take the heat away. Ergo, a house maintained in low humidity in the hot months feel better (cooler) because your body’s cooling system has increased efficiency.
Lastly, conditioned air is also filtered. We think of return air filters as being necessary to maintain a good HVAC system, but the truth is that it benefits us in other ways. A good filter, captures unwanted particles that are airborne, but allows the air to flow nearly unrestricted. The more filtering that happens, the denser the filter needed, and the harder it is for air to move through the filter media. It is important to prepare for denser filters at the time of initial installation to save time and money. Hospitals use very dense filters known as HEPA- High Efficiency Particulate Air filters that must remove 99.97% of particles from the air. These systems must have blowers that are high-static to move air fast enough to allow the Air Conditioner to perform correctly
This post may seem unnecessary to some, but the more you understand the premise of conditioning air in your environment, the better you will understand:
- The problems that may be occurring with your current HVAC System
- What your HVAC Professional is trying to explain
- Whether or not your HVAC Professional is being honest
- What steps you can take to help yourself in an air conditioning outage
- How to prevent problems within your control
So now you have the basics. In later posts we will be able to build on these principles to allow you to do some basic maintenance without having to pay a professional.