An important component of natural ventilation is air change rate or air changes per hour: the hourly rate of ventilation divided by the volume of the space. For example, six air changes per hour means an amount of new air, equal to the volume of the space, is added every ten minutes. For human comfort, a minimum of four air changes per hour is typical, though warehouses might have only two. Too high of an air change rate may be uncomfortable, akin to a wind tunnel which have thousands of changes per hour. The highest air change rates are for crowded spaces, bars, night clubs, commercial kitchens at around 30 to 50 air changes per hour.[17]
Circulating refrigerant vapor enters the compressor, where its pressure and temperature are increased. The hot, compressed refrigerant vapor is now at a temperature and pressure at which it can be condensed and is routed through a condenser. Here it is cooled by air flowing across the condenser coils and condensed into a liquid. Thus, the circulating refrigerant removes heat from the system and the heat is carried away by the air. The removal of this heat can be greatly augmented by pouring water over the condenser coils, making it much cooler when it hits the expansion valve.
Since the 1980s, manufacturers of HVAC equipment have been making an effort to make the systems they manufacture more efficient. This was originally driven by rising energy costs, and has more recently been driven by increased awareness of environmental issues. Additionally, improvements to the HVAC system efficiency can also help increase occupant health and productivity.[24] In the US, the EPA has imposed tighter restrictions over the years. There are several methods for making HVAC systems more efficient.
If your compressor doesn’t have an overload button and you hear it humming or buzzing, poke a screwdriver or stick down through the top grille and try to spin the fan blades clockwise. If doing this gives the fan enough of a boost to get it going, the unit has a faulty capacitor that must be replaced. See How to Test and Replace an AC Run Capacitor, above.
At Genz-Ryan, we are here for you 24 hours a day, 7 days a week so you can count on us for all your heating repair work in the Minneapolis area. Our furnace repair technicians are well-trained and experienced. They’re ready to take care of any heating issue that you may have. We are a Lennox Premier Furnace Dealer and provide expert furnace repair service for most of the Minneapolis/St. Paul area. For over 60 years we have been getting the job done right the first time.
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]

Designed to improve manufacturing process control in a printing plant, Carrier's invention controlled not only temperature but also humidity. Carrier used his knowledge of the heating of objects with steam and reversed the process. Instead of sending air through hot coils, he sent it through cold coils (filled with cold water). The air was cooled, and thereby the amount of moisture in the air could be controlled, which in turn made the humidity in the room controllable. The controlled temperature and humidity helped maintain consistent paper dimensions and ink alignment. Later, Carrier's technology was applied to increase productivity in the workplace, and The Carrier Air Conditioning Company of America was formed to meet rising demand. Over time, air conditioning came to be used to improve comfort in homes and automobiles as well. Residential sales expanded dramatically in the 1950s.[citation needed]


We happily offer all of our services in St Marys county. We view our neighbors in St. Mary’s county as important and valuable as our friends in Calvert. If you live in St Marys and you’re not sure if we can help you with your specific problem, please don’t hesitate to contact us and find out! We value all inquiries and our eager to help and assist our neighbors throughout all of Southern Maryland.
Terrible - Explained to tech that we had cold air on heat status. I placed Thermostat on emergency heat and was able to get some heat. I told him TXU had installed a a new thermostat and I think he may have installed it incorrectly but wasn't, sure. He said it would cost us more money if he fixed problem if there was one. He said I could pay for it and get reimbursed from insurance company. When he said it would cost us money I said I would live with it. I plan on calling a reputable repair company. He did not check furnace or temperature of house

Our team of fully licensed and insured technicians each draw from between ten and thirty years of industry experience and share our unwavering dedication to customer service.  Entirely NATE-certified, our installation and service department has completed rigorous testing, and are exceptionally qualified to handle even the most complex HVAC challenges.  NATE (North American Technician Excellence) is the only nationwide certification program that is supported by the entire industry, and of all third-party certifications, has the lowest pass rate.
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, vehicles such as cars, trains, airplanes, 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.
We happily offer all of our services in St Marys county. We view our neighbors in St. Mary’s county as important and valuable as our friends in Calvert. If you live in St Marys and you’re not sure if we can help you with your specific problem, please don’t hesitate to contact us and find out! We value all inquiries and our eager to help and assist our neighbors throughout all of Southern Maryland.
I had Gator install two train units a year and a half ago. They the blower motor went out on one of the units. I bought Trane because I thought I was buying quality. The warranty only covers labor for the first year. I called Gator in the morning and they were fantastic. The sent a technician out immediately and had the unit operating that day at a very reasonable price. I would recommend Gator to anyone.
Designed to improve manufacturing process control in a printing plant, Carrier's invention controlled not only temperature but also humidity. Carrier used his knowledge of the heating of objects with steam and reversed the process. Instead of sending air through hot coils, he sent it through cold coils (filled with cold water). The air was cooled, and thereby the amount of moisture in the air could be controlled, which in turn made the humidity in the room controllable. The controlled temperature and humidity helped maintain consistent paper dimensions and ink alignment. Later, Carrier's technology was applied to increase productivity in the workplace, and The Carrier Air Conditioning Company of America was formed to meet rising demand. Over time, air conditioning came to be used to improve comfort in homes and automobiles as well. Residential sales expanded dramatically in the 1950s.[citation needed]
We contacted GatorAC and have been pleased through the entire process of the purchase, installation and the daily functioning of the unit. We spoke to Angie to get information about the Trane AC. She arranged for Carlos Garcia to come to the house to determine the unit that would fit our needs. We made the choice between 3 units on Thursday and the unit was installed Friday. The Installation team, Willie Shaw and Gary Barber were the best. When they left everything was done, clean and clear and working great. We would recommend GatorAC for your AC needs.
Hii need you guys help! Once my thermostat drop below the set temp , my furnace does not turn on and I was wondering what’s wrong with it. It happens mostly on cold nights. Sometimes I would have to go in the basement and turned the furnace power switch off then on and will come on once I switch it off then on.i also change the thermostat recently, so I don’t think that’s the problem

Variable-speed technology allows more energy saving potential and improved comfort levels throughout the home.  The ability of the system to automatically adjust speeds according to the needs of the home ensures the right amount of comfort control, right when you need it.  Outside temperatures rarely, if ever, require your HVAC system to operate at 100% capacity.  Variable-speed units determine optimal cooling needs and vary speeds in increments between 40% and 100%.  Not only does this tailor comfort, but by running at lower speeds and consuming less power, you’ll save a significant amount off monthly utility expenses.
We are open from 7am to 10pm every weekday and from 7am to 8pm on weekends. We book appointments in a 2 hour arrival window and call 30-45 mins before we arrive so you do not have to sit around waiting. It is often possible to schedule your appointment in the evening or morning hours to avoid conflicting with your work schedule. Are you looking for service today? Give us a call or click on one of the Schedule Service buttons found on the top and left sides of this page to contact us today.

Air conditioning and refrigeration are provided through the removal of heat. Heat can be removed through radiation, convection, or conduction. Refrigeration conduction media such as water, air, ice, and chemicals are referred to as refrigerants. A refrigerant is employed either in a heat pump system in which a compressor is used to drive thermodynamic refrigeration cycle, or in a free cooling system which uses pumps to circulate a cool refrigerant (typically water or a glycol mix).
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.[30]
We are open from 7am to 10pm every weekday and from 7am to 8pm on weekends. We book appointments in a 2 hour arrival window and call 30-45 mins before we arrive so you do not have to sit around waiting. It is often possible to schedule your appointment in the evening or morning hours to avoid conflicting with your work schedule. Are you looking for service today? Give us a call or click on one of the Schedule Service buttons found on the top and left sides of this page to contact us today.

Whether it’s a sticky day in July and you need an AC repair, or your employees are having trouble breathing because of stagnant indoor air, you can rely on HI-VAC Air Conditioning Service to quickly resolve your problem. We are the go-to source for air conditioning services in Plantation, Miramar, Pembroke Pines, Weston, Coral Springs, Sunrise, FL and the surrounding area. Give us a call today to learn how we can improve your indoor comfort.
Our team of fully licensed and insured technicians each draw from between ten and thirty years of industry experience and share our unwavering dedication to customer service.  Entirely NATE-certified, our installation and service department has completed rigorous testing, and are exceptionally qualified to handle even the most complex HVAC challenges.  NATE (North American Technician Excellence) is the only nationwide certification program that is supported by the entire industry, and of all third-party certifications, has the lowest pass rate.
2) Keep your coils clean. The AC coils and fins on the outside of your unit need to be kept clean and clear of obstructions. Leaves and other debris sometimes accumulate around your unit. If obstructions are present, your unit must work harder to function than it should. You can clean your unit with a regular garden hose and a broom. Do not use a pressure washer, as the strong spray could cause harm to your system. A little bit of housekeeping in this regard goes far toward keeping your air conditioner working optimally. 
I have a very old HVAC. The heater went out. I had just purchased the heater check package from Angie's list and it went out the nex tday. I called them and John came within a day or so. He found the problem after checking several items (fuse in heater shorting). He ordered the part and there was a delay due to getting the part and then the ice storm. As soon as the part was in John texted me. When I was available, John came back in a reasonable time and fixed it. He always called half hour before he was en route to notify me and was very punctual. He is professional and knowledgeable. He used my coupon toward my total bill and I have heat! I will use him again and am thankful he could get out and get it fixed at a reasonable cost.
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