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]
Air flow meter Aquastat BACnet Blower door Building automation Carbon dioxide sensor Clean Air Delivery Rate (CADR) Gas sensor Home energy monitor Humidistat HVAC control system Intelligent buildings LonWorks Minimum efficiency reporting value (MERV) OpenTherm Programmable communicating thermostat Programmable thermostat Psychrometrics Room temperature Smart thermostat Thermostat Thermostatic radiator valve
Cut down on energy costs and prevent damage to your furnace by addressing a gas furnace that's overactive or short cycling. Besides the need for consistently comfortable temperatures, this issue could cause long-term safety issues to your home, making it very important to address. From a faulty thermostat to a dirty filter, there are several possible causes to investigate.

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]
A gas that can be retrofitted into a refrigeration system designed for another, without major system changes. For example, R422D is a drop-in replacement for R22 in many applications. However, hydrocarbon refrigerants are NOT drop-in alternatives for most fluorocarbon refrigerants due to substantial system changes needed to manage their differing characteristics (e.g. flammability).
High-efficiency condensing furnaces (90% AFUE and above) are a bit more complex than conventional furnaces. The main differences between a conventional and condensing furnace are the heat exchanger technology used to extract heat from the combustion process and the method used to exhaust the combustion gases. In these ways, the furnaces are very different. The condensing furnace does not have a significantly more efficient combustion process than does a conventional furnace; both use gas burners with electronic ignition. The difference lies in that the condensing furnace has a more efficient heat extraction process after combustion.
When central air conditioning service fails during a heat spell, you may have to wait days for an HVAC repair technician or a ac contractor to show up, and you’ll probably pay at least several hundred for the repair. But if you’re comfortable working around electricity and are willing to spend about $50 on parts, you can probably repair your air conditioning service yourself in about two hours and save about $225 on parts markup and labor.

This may apply to a system using fresh air for cooling the space or a water cooled or glycol cooled system with an additional coil that provides chilled water cooling when the outdoor ambient is cold; thereby reducing or eliminating compressor operation. These systems may provide free cooling for up to 80% of their operating life, particularly when operating in Northerly climates. See our Free Cooling page for more information.

"Warren at Lighten Up came in on time and as scheduled. Loved working with him. He provided new lighting for our kitchen remodel and did a great job. He still needs to come back and hook everything up. Also Seth came in and did some plumbing work and repair that we did not even know needed repair. I highly recommend this company and look forward to working with them in the future"
"Warren at Lighten Up came in on time and as scheduled. Loved working with him. He provided new lighting for our kitchen remodel and did a great job. He still needs to come back and hook everything up. Also Seth came in and did some plumbing work and repair that we did not even know needed repair. I highly recommend this company and look forward to working with them in the future"
Read what our many satisfied customers say about Moncrief. We consistently receive 5-star reviews from both our commercial and residential customers. Moncrief's legacy of comfort and trust, as well as our great team and customer service are second to none. Contact us today to schedule an appointment or inquire about our Total Comfort Service Plan. Moncrief Heating & Air Conditioning is the company to provide the services you need in Roswell and Marietta. Call us at 404-350-2300.

If you’re looking for a professional heating company in Denver with the proper experience to handle your project, our crew has many years of training and experience on most major heating systems available in the Denver area. Our heating company in Denver understands that in some situations, the scope of the damage may put the units beyond repair. In this instance, we can offer you help finding the right energy efficient model that will provide you warmth and savings in your wallet. Heating in Denver can be expensive during the coldest time of year, so choosing the right heating system can give the same amount of heat while at the same time providing big savings when our Denver heater repair technicians help you pick the right system for your home.
Cut down on energy costs and prevent damage to your furnace by addressing a gas furnace that's overactive or short cycling. Besides the need for consistently comfortable temperatures, this issue could cause long-term safety issues to your home, making it very important to address. From a faulty thermostat to a dirty filter, there are several possible causes to investigate.
With that being said, we ask ourselves, “How do we ensure our customers that we are the company they can count on?”. It all starts with our people. Each of our team members have passed a criminal background and drug test, so you can trust them with your home and family. We are licensed and insured well beyond the minimum requirements set for by the State of Texas. Also, we provide continuous training for both the technical and customer service aspects of our industry. We do this in order to make sure that we are ready and able to serve your needs with excellence.
We take great pride in our crew, choosing the best and brightest to represent R.S. Andrews in the face of an emergency. Our HVAC contractors boast not only unparalleled skill but also a friendly and professional demeanor. All of our work comes completely guaranteed, and we won’t rest until your emergency has been resolved to your full satisfaction!

If the condenser coils are clogged, the compressor can overheat and shut down. You’ll experience intermittent periods of minimal cooling, followed by no cooling. Even if you’re “sure” the condenser coils are clean, clean them again. Turn off the power. Flip the air conditioning service and furnace circuit breakers in your main electrical panel to the “Off” position. Next, turn off the power switch right at the furnace or air handler. Then yank the disconnect block (Photo 1) and clean the condenser coils (Photo 2). If the air conditioning service still doesn’t work properly after you’ve cleaned the condenser coils, installed a new filter and opened all the supply vents, proceed with the following repairs.
Capacitors -- Capacitors help your HVAC motor start from a standstill. Over time they can weaken. As they weaken, they cause the motor to run hotter. This can shorten the life expectancy of your motor. Once a capacitor fails, the whole motor will stop working. You usually won't notice that a capacitor has weakened until your motor stops turning on.

Lennox was started to offer some of the most long-lasting, reliable HVAC systems in the market while providing the best service and quality for customers. Knoechel Heating Company in Zelienople is no different, with our on-going dedication to your comfort and commitment to the community. We strive to be the experts at what we do so you can always be comfortable, and know you can always count on us. Give us a call at 724-452-6280 or arrange an appointment with us so we can help you achieve whole home comfort. 


BGE HOME HVAC repair technicians are thoroughly trained and certified to work on all major brands of heating and air conditioning equipment. When your system breaks down and needs a heating and air conditioning repair, you want to call someone you can trust. Need air conditioning service in the middle of the night? Emergency heating and cooling HVAC service is available 24 hours a day by calling 888-243-4663.
"Jorge Mondragon did a fantastic job installing a new upstairs AC and furnace. His price was close to the best that I received, and after seeing the positive reviews on Thumbtack, I decided to give him the job. He came in with two other crewman and worked about a half day to get the job done. They used tarps on the floor and covered the entire section they walked on during the install, including the stairs. The new AC works great, although the real test will come when the brutal summer kicks in. I'll update my review once I have a few months on the unit. The install job looked thorough and well done. Professional, polite, well-spoken, and hardworking. This is my go-to company for all future HVAC needs and I'll be recommending him to everyone I know."

If you believe that the ac not working or you’re getting little or no cold air, check these three things first. Make sure all the registers in the house are wide open. Then be sure the furnace filter is clean. Then go outside and clean off the condenser coils (Photo 2). If several registers were closed or the filter was clogged, the reduced airflow could have caused the evaporator coil to ice up and stop cooling your home. If you’ve changed the filter and opened all the registers and you’re still not getting airflow at the registers, deice the A-coil. Move the thermostat mode switch from “Cooling” to “Off” and move the fan switch from “Auto” to “On.” Let the blower run for at least 30 minutes or until there’s good airflow at the registers. Then turn the AC back on to test it. If it works for the next 12 hours, you’ve solved the problem.
Extensive training – Over the years, we have had to learn continually and update our skills to stay top-of-the-line. We continue to offer state-of-the-art products today with the service skills to match. We offer 800 hours of training classes to our technicians every year. They also have access to factory resource personnel and engineers for consultation.
The main problem when installing a multi-split system is the laying of long refrigerant lines for connecting the external unit to the internal ones. While installing a separate split system, workers try to locate both units opposite to each other, where the length of the line is minimal. Installing a multi-split system creates more difficulties, since some of indoor units can be located far from the outside. The first models of multi-split systems had one common control system that did not allow you to set the air conditioning individually for each room. However, now the market has a wide selection of multi-split systems, in which the functional characteristics of indoor units operate separately from each other.

Split ductless systems have an outside condenser and compressor, and one to four or more indoor blower units, called air handlers, mounted high on the wall that distribute air. The indoor and outdoor sections are connected by a thin conduit that houses the power cable, refrigerant tubing, and a condensate drain. The conduit is run through about a 3-inch hole hidden behind each air handler. Each air handler cools the room in which it’s installed, and you set the temperature with a remote control. Split ductless systems can be more expensive than window air conditioners, and professional installation is recommended. While not technically central air, the cooling they provide can feel like a central air system.
A number of other variables can influence your decision on whether to repair or replace your furnace, as well. In addition to cost and brand, consider the expected lifetime of your furnace. If it is more than 15 years old, it might make more sense to invest in a new unit even if it costs more than simply repairing the current problem. Long-term costs also play into the equation. For example, your new furnace may be more energy efficient than the current unit. Even though you will pay more for the actual installation, you might be able to make back your investment through lower energy bills. To make your decision, consult with a reliable professional on what to do. In inspecting your furnace, they will be able to make an informed recommendation that looks not just to the next year, but years into the future. That way, you can make the best possible decision for your home and budget long-term.
In the case of heated water or steam, piping is used to transport the heat to the rooms. Most modern hot water boiler heating systems have a circulator, which is a pump, to move hot water through the distribution system (as opposed to older gravity-fed systems). The heat can be transferred to the surrounding air using radiators, hot water coils (hydro-air), or other heat exchangers. The radiators may be mounted on walls or installed within the floor to produce floor heat.
Refrigerant 22 (R-22 or MonoChloroDiFlouroMethane, CHClF2) is one of the most common refrigerants and is used in a wide variety of applications such as refrigeration, aerosol propellants, cleaning solvents, and foaming agents for plastics. This refrigerant is believed to be partially responsible for damaging the earth’s ozone layer and it’s use is being phased out over the next two decades. The ozone layer is a result of sunlight reacting with oxygen to produce a layer in the stratosphere more than 10 km above the earth’s surface. As R-22 refrigerant escapes from an AC system through leaks or is released into the atmosphere by other means, the R-22 molecule containing the chlorine atom (“monochloro”) rises in the atmosphere. Sunlight breaks down the R-22 molecule to yield a free chlorine radical (Cl-). The free chlorine radical combines with ozone (O3), decomposing it into normal oxygen (O2).
Demand controlled kitchen ventilation (DCKV) is a building controls approach of slowing down kitchen exhaust fans and subsequent supply air in response to the actual cooking loads in a commercial kitchen. Traditional commercial kitchen ventilation systems operate at 100% fan speed independent of the volume of cooking activity and DCKV technology changes that to provide significant fan energy and conditioned air savings. By deploying smart sensing technology, both the exhaust and supply fans can be controlled to capitalize on the Law of Affinity for motor energy savings, reduce makeup air heating and cooling energy, increasing safety and reducing ambient kitchen noise levels.[27]
A hot aisle is a layout design for server racks and other computing equipment in a data centre. Hot aisle data centre design involves lining up server racks in alternating rows with cold air intakes facing one way and hot air exhausts facing the other. The rows the heated exhausts pour into are called hot aisles. See Data Centre Aisle Containment for more information. 

Headquartered in Portsmouth, Virginia, Air Conditioning Specialists was established in 1997 and is a fully licensed, insured and experienced heating and cooling company. We strive to provide our customers with the quickest, most efficient HVAC service and installation. Our workmanship, along with the highest quality of home and business products available, ensures the dependable performance of your HVAC system and your family’s comfort year after year. Our staff welcomes the opportunity to serve you, and looks forward to building a long-term relationship. Our success is dependent upon 100% customer satisfaction and the referrals we receive from our many satisfied customers.


Geothermal Heating and Cooling systems are unmatched in every way. This green alternative to temperature control is three times more efficient than conventional systems. Recognized by the US Environmental Protection Agency as the most environmentally-friendly option available today, installation of a geothermal HVAC system translates into a 50% reduction in heating costs, 30% reduction in cooling costs, and a 65% potential savings on hot water costs.  Sky Heating & Air Conditioning is now the largest WaterFurnace geothermal contractor west of Iowa. Our team of experienced professionals offer conscientious and skilled start-to-finish installation and service.  We specialize in outstanding geothermal HVAC systems, adding value and enjoyment to your home through sustainable solutions to year round temperature control. Contact Sky Heating & Air Conditioning for geothermal heat pump installation in Portland.
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