The use of furnaces, space heaters, and boilers as a method of indoor heating could result in incomplete combustion and the emission of carbon monoxide, nitrogen oxides, formaldehyde, volatile organic compounds, and other combustion byproducts. Incomplete combustion occurs when there is insufficient oxygen; the inputs are fuels containing various contaminants and the outputs are harmful byproducts, most dangerously carbon monoxide, which is a tasteless and odorless gas with serious adverse health effects.[14]
Humidity is becoming more of a concern to building operators and owners. High indoor humidity leads to mold and mildew growth inside the building. The are several methods of controlling indoor humidity. The simplest (and most expensive) method is to connect a humidistat to an electric heater. When the humidity inside the building rises above the humidistat set point, the heater is turned on. The additional heat causes the air conditioning system to run longer and remove more moisture.
The heat pump gained popularity in the 1950s in Japan and the United States.[13] Heat pumps can extract heat from various sources, such as environmental air, exhaust air from a building, or from the ground. Initially, heat pump HVAC systems were only used in moderate climates, but with improvements in low temperature operation and reduced loads due to more efficient homes, they are increasing in popularity in cooler climates.
A packaged system is a single unit combining all the components described in the split system. Since the unit is a package, it must be placed outside the building and indoor air is “ducted” from the building to the packaged system and back through an air distribution system. These units typically have SEER rating from 10 to 18. If heating is required, an alternate method of heating the interior of the building must be used, usually in the form of electric or gas heating.
Free cooling systems can have very high efficiencies, and are sometimes combined with seasonal thermal energy storage so that the cold of winter can be used for summer air conditioning. Common storage mediums are deep aquifers or a natural underground rock mass accessed via a cluster of small-diameter, heat-exchanger-equipped boreholes. Some systems with small storages are hybrids, using free cooling early in the cooling season, and later employing a heat pump to chill the circulation coming from the storage. The heat pump is added-in because the storage acts as a heat sink when the system is in cooling (as opposed to charging) mode, causing the temperature to gradually increase during the cooling season.
HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels and senior living facilities, medium to large industrial and office buildings such as skyscrapers and hospitals, on ships and submarines, and in marine environments, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors.
Heat pipe heat exchangers or run-around coils perform a similar function when humidity control is required. Two heat exchanger are placed in the air stream, one upstream of the cooling coil and the other downstream of the cooling coil. These heat exchangers are connected together with piping. A heat transfer fluid, whether it be water or refrigerant, is either pumped or gravity fed from one heat exchanger to the other. The heat exchanger down stream of the cooling coil (re-heat coil) cools the liquid medium inside the heat exchanger and heats the air passing over the heat exchanger. The cold liquid inside the heat exchanger is moved to the heat exchanger upstream of the cooling coil (pre-cool coil) where it pre-cools the air passing over the heat exchanger and warms the liquid passing through the heat exchanger. The affect of a heat pipe or run-around coil is to reduce the sensible heat capacity of the AC system. The latent capacity of the AC system increases if direct-expansion equipment is used or remains relatively constant if chilled water equipment is used. Since the sensible capacity of the AC system has been reduced, the system must run longer to meet the thermostat set point thereby removing more moisture.
Smyrna homes and businesses have relied on Coolray for air conditioning service and installation since 1966. We can provide repair and maintenance on all makes and models of air conditioners for your home or business and offer 24 hour emergency AC repair service. We also offer a wide range of new air conditioning systems and our expert air conditioning technicians can help you select an air conditioner or heat pump that is right for your home and budget.
Some of these components can be repaired or replaced by the homeowner, such as filters, fuses, and clogged up drain lines. Coils, compressors and the other components are best left to a professional. In some cases, you may have a system that is so old that parts are no longer available or else they aren't up to code. In this case you will have to consider replacing the entire system.
The selection of indoor units has one restriction: their total power should not exceed the capacity of the outdoor unit. In practice, however, it is very common to see a multi-split system with a total capacity of indoor units greater than the outdoor capacity by at least 20%. However, it is wrong to expect better performance when all indoor units are turned on at the same time, since the total capacity of the whole system is limited by the capacity of the outdoor unit. Simply put, the outdoor unit will distribute all its power to all operating indoor units in such a way that some of the rooms may not have a very comfortable temperature level. However, the calculation of the total power is not simple, since it takes into account not only the nominal power of the units, but also the cooling capacity, heating, dehumidification, humidification, venting, etc.

R-22 Freon is being phased out & isn't readily available. So the service company may only purchase as needed and the lack of availability would make their cost high. But, as long as they can get it, whatever the cost, unfortunately, is less expensive than replacing the A/C. Which will be the case eventually since it's no longer manufactured or sooner as in my case with a not so old a/c that sprang a leak, that would have been just a repair, but since it uses R-22 the whole unit has to be upgraded(replaced).  

Most modern air-conditioning systems feature a dehumidification cycle during which the compressor runs while the fan is slowed as much as possible[citation needed] to reduce the evaporator temperature and therefore condense more water. When the temperature falls below a threshold, both the fan and compressor are shut off to mitigate further temperature drops;[clarification needed] this prevents moisture on the evaporator from being blown back into the room.[citation needed] When the temperature rises again,[clarification needed] the compressor restarts and the fan returns to low speed.
The 2nd-century Chinese mechanical engineer and inventor Ding Huan of the Han Dynasty invented a rotary fan for air conditioning, with seven wheels 3 m (10 ft) in diameter and manually powered by prisoners of the time.[6] In 747, Emperor Xuanzong (r. 712–762) of the Tang Dynasty (618–907) had the Cool Hall (Liang Dian 涼殿) built in the imperial palace, which the Tang Yulin describes as having water-powered fan wheels for air conditioning as well as rising jet streams of water from fountains. During the subsequent Song Dynasty (960–1279), written sources mentioned the air conditioning rotary fan as even more widely used.[7]
Dunes Heating And Air Conditioning is HVAC Contractor providing the best possible Heating and Air Conditioning Repair, maintenance and installation for your home or business in Mount Pleasant, Charleston and Isle of Palms South Carolina. You can count on us to provide you with a system and solution that fits your unique needs and since we've installed many systems in this area, we've earned a reputation for doing the job right the first time.
When the thermostat calls for heat, 24 volts are sent to the electronic ignition control module, which energizes the furnace blower and other systems and sends 120 volts to the HSI. The HSI heats up to around 1,800°F to 2,500°F and glows red-hot. Then the gas valve opens, and the burner gas is ignited by the HSI. Once a proper flame is sensed by the flame sensor, the HSI turns off and stays off until the next heating cycle. In some furnaces, the HSI also serves as a flame sensor (called local sensing) instead of having a separate sensing rod in the burner flame (remote sensing).
In order to make your everyday life easier and more enjoyable, Sky Heating & Air Conditioning specializes in state-of-the-art heating and cooling technology, partnering with Trane, Mitsubishi, and Waterfurnace.  We bring you HVAC solutions that represent the best the industry has to offer, ensuring long-term performance and satisfaction.  Whether you’re looking for the design/build of a new system, replacement, or hoping to cut costs and enhance convenience, we answer with proven products.  Our qualified HVAC technicians help you determine the ideal solution for your exact requirements, and make sure you’re happy with every step of the process.  From ductless HVAC to geothermal heating and cooling systems, we offer a wide selection of options and comprehensive services to answer any type of challenge.  Call on Sky Heating & Air Conditioning and let us exceed your expectations today!