Without proper ventilation, carbon monoxide can be lethal at concentrations of 1000 ppm (0.1%). However, at several hundred ppm, carbon monoxide exposure induces headaches, fatigue, nausea, and vomiting. Carbon monoxide binds with hemoglobin in the blood, forming carboxyhemoglobin, reducing the blood's ability to transport oxygen. The primary health concerns associated with carbon monoxide exposure are its cardiovascular and neurobehavioral effects. Carbon monoxide can cause atherosclerosis (the hardening of arteries) and can also trigger heart attacks. Neurologically, carbon monoxide exposure reduces hand to eye coordination, vigilance, and continuous performance. It can also affect time discrimination.[15]
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]
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]

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.


Turn off the gas supply valve, typically located by your gas meter on the gas inlet pipe. Turn off the gas by rotating the valve one quarter turn with an adjustable wrench. When the gas is off,  the valve’s oblong stem points perpendicular to the inlet pipe. Then call your gas utility or the fire department from a remote location. Do not return to your home until you know it is safe.
Poorly maintained water cooling towers can promote the growth and spread of microorganisms,[56] such as Legionella pneumophila, the infectious agent responsible for Legionnaires' disease, or thermophilic actinomycetes. As long as the cooling tower is kept clean (usually by means of a chlorine treatment), these health hazards can be avoided or reduced. Excessive air conditioning can have a negative effect on skin, causing it to dry out, and can also cause dehydration.[citation needed]
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.
If you already have a newer condenser, the worst noise is probably coming from the compressor. (Fans on newer units are very quiet.) Contact the manufacturer to find a sound blanket for your model or buy a universal blanket (search online for “compressor sound blanket”). Installation is easy. Don’t bother putting a blanket on an old unit—you’ll still hear the noisy fan. Here are other possible solutions for a noisy air conditioner.
An alternative to packaged systems is the use of separate indoor and outdoor coils in split systems. Split systems are preferred and widely used worldwide except in North America. In North America, split systems are most often seen in residential applications, but they are gaining popularity in small commercial buildings. The split systems are a great choice for small buildings where ductwork is not feasible or where the space conditioning efficiency is of prime concern [21]. The benefits of ductless air conditioning systems include easy installation, no ductwork, greater zonal control, flexibility of control and quiet operation [22]. In space conditioning, the duct losses can account for 30% of energy consumption [23]. The use of minisplit can result in energy savings in space conditioning as there are no losses associated with ducting.

In 1820, English scientist and inventor Michael Faraday discovered that compressing and liquefying ammonia could chill air when the liquefied ammonia was allowed to evaporate. In 1842, Florida physician John Gorrie used compressor technology to create ice, which he used to cool air for his patients in his hospital in Apalachicola, Florida. He hoped to eventually use his ice-making machine to regulate the temperature of buildings. He even envisioned centralized air conditioning that could cool entire cities. Though his prototype leaked and performed irregularly, Gorrie was granted a patent in 1851 for his ice-making machine. Though his process improved the artificial production of ice, his hopes for its success vanished soon afterwards when his chief financial backer died and Gorrie did not get the money he needed to develop the machine. According to his biographer, Vivian M. Sherlock, he blamed the "Ice King", Frederic Tudor, for his failure, suspecting that Tudor had launched a smear campaign against his invention. Dr. Gorrie died impoverished in 1855, and the dream of commonplace air conditioning went away for 50 years.[citation needed]

Hospital operating theatres, in which air is filtered to high levels to reduce infection risk and the humidity controlled to limit patient dehydration. Although temperatures are often in the comfort range, some specialist procedures, such as open heart surgery, require low temperatures (about 18 °C, 64 °F) and others, such as neonatal, relatively high temperatures (about 28 °C, 82 °F).
*We work on all brands: Adams, Aire-Flo, Amana, Arcoaire, Armstrong, Beutler, Bryant, Carrier, Centurion, Coleman, Comfortmaker, Cozy, Daikin, Day & Night, Dayton, Ducane, Emerson, Empire, Evcon, Fedders, Friedrich, Frigidaire, Fujitsu, Gaffers & Statler, General Electric, Gibson, Goldstar, Goodman, GMC, Haier, Heil, Honeywell, Intertherm, Janitrol, Kenmore, Lennox, Luxaire, Maytag, Mitsubishi, Payne, Rheem, Ruud, Samsung, Sanyo, Sears, Sharp, Spartan, Tappan, Tempstar, Thermal Solutions, Trane, Utica, Weatherking, Westinghouse, Whirlpool, Williams, York, and Zephyr.
Some systems include an "economizer mode", which is sometimes called a "free-cooling mode". When economizing, the control system will open (fully or partially) the outside air damper and close (fully or partially) the return air damper. This will cause fresh, outside air to be supplied to the system. When the outside air is cooler than the demanded cool air, this will allow the demand to be met without using the mechanical supply of cooling (typically chilled water or a direct expansion "DX" unit), thus saving energy. The control system can compare the temperature of the outside air vs. return air, or it can compare the enthalpy of the air, as is frequently done in climates where humidity is more of an issue. In both cases, the outside air must be less energetic than the return air for the system to enter the economizer mode.
Furnace breakdowns, no cooling when outside temperatures are soaring – heating and cooling repairs often catch us unexpectedly, making HVAC repair costs quite a surprise. Many homeowners worry when calling the HVAC repair contractor because of unexpected costs – your heating and cooling contractor won’t be able to give you a price for the repairs needed until he or she inspects the system to find the source of the problem.

Turn off the gas supply valve, typically located by your gas meter on the gas inlet pipe. Turn off the gas by rotating the valve one quarter turn with an adjustable wrench. When the gas is off,  the valve’s oblong stem points perpendicular to the inlet pipe. Then call your gas utility or the fire department from a remote location. Do not return to your home until you know it is safe.


We relocate frequently and one of the biggest hassles of relocating to new areas is finding reputable companies that send qualified technicians to perform work when you need it, whether for annual preventative maintenance or during a house emergency. We’ve been through the process several times and always dread researching and trying new companies. This was our first HVAC call here in northern Virginia. We are in new construction and chose not to use the builder’s sub-contractor for a technician call but looked through Carrier’s website for a local business. Jeremy Garner with HVAC Unlimited responded to our service request the morning following our call. I shadowed him performing work and he was patient while I peppered him with questions. He helped expand my HVAC knowledge in order to be a better property owner of our systems. He performed the work we thought was necessary, in a timely and professional manner, and gave us options for future annual maintenance. HVAC Unlimited is definitely on our list of go-to contractors.

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