By, Lindsay Doud, Century A/C Supply
When I first started out in the HVAC industry, I was a little clueless about how air-conditioners worked. I honestly thought these magical machines whipped up cold air (don’t ask me how) and dispensed it into the different rooms it had been mapped to via ductwork. I had it all backwards. I have come to learn that air-conditioning is more about removing heat than dispensing cold air. Please see Exhibit A.
Heat is a rule follower. It follows the rules of physics that say heat will always want to move to places of non-heat or “cold”. The red color in the circuit above indicates where heat travels. Heat travels through the home with the help of a little friend, named refrigerant. Cold liquid refrigerant flows through the coil of the evaporator (the blue coil in the pic above). The cold refrigerant attracts the heat in the room, and it is drawn from the room to the coil via return grills. An example would be this white grill below the air handler, or any on the wall that looks like the return air grill below.
It is through these openings that the hot air makes its way to the cold refrigerant in the evaporator coil. While passing over the evaporator coil, there is a transfer of heat from the hot air to the cold refrigerant. The refrigerant begins to vaporize due to the amount of heat it is picking up. That vapor continues to pick up heat, raising the temperature of the vapor above its saturation temperature, which we refer to as superheating. The air, having given off its heat and thus being much cooler, is returned to the rooms of your room via supply grilles. Supply grilles may have louvers that help direct the flow of the cold air to different parts of the room. The superheated vapor from the evaporator coil then travels through the suction line to the condenser outdoors, that then deposits that hot air into the hotter air around it.
When you understand this process, you began to understand how important having clean filters is for the health of the HVAC system. A filter is placed in the return air grill, and or sometimes placed directly below the coil in the air handler. When filters get dirty, caked with dust, pet hair, and other particles, it makes it impossible for the hot air to get through to the cold refrigerant. Your evaporator can freeze because the refrigerant in the system is not getting the heat it needs from the room to become a superheated vapor. It can even cause compressor problems if the refrigerant is not heated enough to become a vapor. You then get liquid refrigerant coming back to your compressor, which will completely ruin a compressor. A compressor can cost you $350-$600 dollars, depending on the brand and tonnage of the compressor.
When you look at the return and supply grills in your home, I hope you now understand a little bit more about the magic of air-conditioning. Isn’t it a wonderful invention?
Lindsay Doud, Sales Coordinator, Ruud Region, Century A/C Supply
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