Most central air conditioners have two basic parts: an outdoor unit (compressor/condenser) that sits next to your home and an indoor unit (evaporator) that’s located in a central duct near your furnace. If you have a heat pump instead of a furnace, the indoor unit will be in the air handler. Use the same maintenance steps we show here. If your furnace looks different from the one shown or you have a heat pump, use the owner’s manual to find your way around it. The basic parts will be the same. Check out our step-by-step guide for deep-cleaning your home air conditioner.

It’s a rare occasion for a problem to arise with your heating or cooling equipment at a convenient time. In fact, we’re not even certain such a time exists! That’s why the team at HVAC & Plumbing Unlimited stands ready to provide complete emergency heating and cooling repairs. No matter the time of day or the day itself, we can be on the way and ready to provide prompt, cost-efficient services to our Alexandria clients.*
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.
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

Air conditioners often use a fan to distribute the conditioned air to an occupied space such as a building or a car to improve thermal comfort and indoor air quality. Electric refrigerant-based AC units range from small units that can cool a small bedroom, which can be carried by a single adult, to massive units installed on the roof of office towers that can cool an entire building. The cooling is typically achieved through a refrigeration cycle, but sometimes evaporation or free cooling is used. Air conditioning systems can also be made based on desiccants (chemicals which remove moisture from the air) and subterraneous pipes that can distribute the heated refrigerant to the ground for cooling.[2]
Recent Review: Metro Service was amazing. They came out on Saturday and secured the gas to a failing furnace to insure our safety. They came out on Monday and had the new furnace installed and operating within less than 4 hours. Polite, professional, meticulous and 35% lower than their competitors. I will be using them for all of my HVAC needs in the future.
No one wants to be stuck in the dead of summer with a broken air conditioner, or in the cold of winter with a broken furnace or boiler. That’s why we’re available any time of day to make your emergency heating and air conditioning repair and get your system up and running as quickly as possible. We’ll show up on time, in uniform and ready to make your HVAC repair right the first time.

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]


If your furnace is more than 15 years old or broken beyond repair, furnace replacement is necessary. Old furnaces are very inefficient which means that you could be spending more on your gas or electric bill than you need to. Old furnaces can also be very hazardous to your health and home. Furnaces are basically controlled fires, and when the control systems on your furnace are out of date or malfunctioning, the safety of your home is in jeopardy. If you have an old or malfunctioning furnace, or if you want a safety check on your current system, then give our furnace replacement company a call today!

At times, malfunctions strike without warning.  These problems rarely stick to regular business hours.  When your comfort, safety, and well-being is at stake, don’t wait for Monday morning.  The service team from Ferran Services is available 24/7 to provide the prompt and dependable assistance you require.  Fully-stocked service trucks and extensively trained technicians allow us to handle the majority of repair requirements in a single visit.  We work on all makes and models, and our technicians do not rely on commission.  We never take advantage of your desperate situation, never sell you a product or service you don’t need, and always keep you informed.  By relying on Factory Authorized Parts, we restore system efficiency, sound levels, and longevity.


Put simply, any home that uses air pushed through ductwork for heating purposes takes advantage of forced air heating. In other words, this term refers not to your furnace, but to the delivery method of the heat throughout your home. Forced air heating is possible with electric or gas furnaces, or a heat pump. Any issues with this delivery system that aren't directly related to the furnace likely have to do with the duct work, which costs between $35 and $55 per linear square foot to repair, or the air handling unit.
Air conditioning can also be provided by a process called free cooling which uses pumps to circulate a coolant (typically water or a glycol mix) from a cold source, which in turn acts as a heat sink for the energy that is removed from the cooled space. Common storage media are deep aquifers or a natural underground rock mass accessed via a cluster of small-diameter boreholes, equipped with heat exchanger. Some systems with small storage capacity are hybrid systems, 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 because the temperature of the storage gradually increases during the cooling season, thereby declining its effectiveness.

A programmable thermostat is a must-have in today’s state of AC technology. Programmable thermostats allow you to set temperatures for various times throughout the day and automatically lower the temperature when you most need it to help you save money and manage your cooling without constantly hovering over the dial. In this article, we’ll walk you through installing a programmable thermostat in your home.
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.
Ground source, or geothermal, heat pumps are similar to ordinary heat pumps, but instead of transferring heat to or from outside air, they rely on the stable, even temperature of the earth to provide heating and air conditioning. Many regions experience seasonal temperature extremes, which would require large-capacity heating and cooling equipment to heat or cool buildings. For example, a conventional heat pump system used to heat a building in Montana's −70 °F (−57 °C) low temperature or cool a building in the highest temperature ever recorded in the US—134 °F (57 °C) in Death Valley, California, in 1913 would require a large amount of energy due to the extreme difference between inside and outside air temperatures. A few feet below the earth's surface, however, the ground remains at a relatively constant temperature. Utilizing this large source of relatively moderate temperature earth, a heating or cooling system's capacity can often be significantly reduced. Although ground temperatures vary according to latitude, at 6 feet (1.8 m) underground, temperatures generally only range from 45 to 75 °F (7 to 24 °C).
Packaged terminal air conditioner (PTAC) systems are also known as wall-split air conditioning systems.[36] They are ductless systems. PTACs, which are frequently used in hotels, have two separate units (terminal packages), the evaporative unit on the interior and the condensing unit on the exterior, with an opening passing through the wall and connecting them. This minimizes the interior system footprint and allows each room to be adjusted independently. PTAC systems may be adapted to provide heating in cold weather, either directly by using an electric strip, gas, or other heater, or by reversing the refrigerant flow to heat the interior and draw heat from the exterior air, converting the air conditioner into a heat pump. While room air conditioning provides maximum flexibility, when used to cool many rooms at a time it is generally more expensive than central air conditioning.
In 1758, Benjamin Franklin and John Hadley, a chemistry professor at Cambridge University, conducted an experiment to explore the principle of evaporation as a means to rapidly cool an object. Franklin and Hadley confirmed that evaporation of highly volatile liquids (such as alcohol and ether) could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to speed up the evaporation. They lowered the temperature of the thermometer bulb down to −14 °C (7 °F) while the ambient temperature was 18 °C (64 °F). Franklin noted that, soon after they passed the freezing point of water 0 °C (32 °F), a thin film of ice formed on the surface of the thermometer's bulb and that the ice mass was about 6 mm (1⁄4 in) thick when they stopped the experiment upon reaching −14 °C (7 °F). Franklin concluded: "From this experiment one may see the possibility of freezing a man to death on a warm summer's day."[9]
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