If you need help with your air conditioner or want to learn more about the types of air conditioners available for your home comfort needs, explore HVAC.com’s HVAC Contractor Directory. Through the directory, you’ll be connected with local cooling contractors who can answer your questions and help you determine the best system and best value for your home. Just enter your ZIP code to see local HVAC contractors near you!
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.
In a thermodynamically closed system, any power dissipated into the system that is being maintained at a set temperature (which is a standard mode of operation for modern air conditioners) requires that the rate of energy removal by the air conditioner increase. This increase has the effect that, for each unit of energy input into the system (say to power a light bulb in the closed system), the air conditioner removes that energy.[30] To do so, the air conditioner must increase its power consumption by the inverse of its "efficiency" (coefficient of performance) times the amount of power dissipated into the system. As an example, assume that inside the closed system a 100 W heating element is activated, and the air conditioner has a coefficient of performance of 200%. The air conditioner's power consumption will increase by 50 W to compensate for this, thus making the 100 W heating element cost a total of 150 W of power.

If you find yourself having a more traditional concern, we can help with that as well. Whether you’re looking to upgrade to a more energy efficient system, require an emergency furnace repair, or need to schedule an annual appointment, we’re here to help. We can tackle any issue or concern that you may have with your HVAC system. Our team will give you confidence and peace of mind when it comes to your HVAC system.
Relative humidity is the ratio of the partial pressure of water vapour in an air-water mixture to the saturated vapour pressure of water at a prescribed temperature. In prevailing Northern European conditions relative humidity and percentage saturation (ration of moisture content) can be considered the same as the divergence is <1%.  In high temperature areas they should be treated differently as the divergence may be as high as 10%.
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The contactor (relay) and start/run capacitor(s) (see illustration below) fail most often and are inexpensive. So it’s a safe bet to buy and install those parts right away, especially if your air conditioning service unit is older than five years. The condenser fan motor can also fail, but it runs about $150 — hold off buying that unless you’re sure that’s the culprit.
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.
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).

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.


Once warm air inside your home blows across the indoor evaporator coil, its heat energy transfers to the refrigerant inside the coil. That transfer, in turn, “cools” the air. The refrigerant is pumped back to the compressor where the cycle begins again. The heat absorbed by the refrigerant is moved outside your home while cooled air is blown inside. Moisture that contributes to humidity is also condensed out of the air. Your cooling system is usually combined with your central heating system because they share the same ductwork for distributing conditioned air throughout your home.
Central heating systems have a primary heating appliance, such as a furnace, typically located in your basement or garage. All furnaces consist of four main components: 1) burners that deliver and burn fuel, 2) heat exchangers, 3) a blower and 4) a flue that acts as an exhaust for gaseous by-products. Depending on your situation, region and needs, you can choose from heating systems running on either gas or oil as fuel, or a hybrid packaged system that can use both fuel types.
In variable climates, the system may include a reversing valve that switches from heating in winter to cooling in summer. By reversing the flow of refrigerant, the heat pump refrigeration cycle is changed from cooling to heating or vice versa. This allows a facility to be heated and cooled by a single piece of equipment by the same means, and with the same hardware.
In addition to installing new HVAC systems from scratch and repairing them day and night, we also care about your indoor air quality. After all, it’s not enough to think about temperature alone. You also have to consider the relative humidity of your space, as well as eliminating as many contaminants and pollutants as possible. That means installing a whole-house air purifier or UV air purifier, and possibly a dehumidifier or humidifier. What’s more, our technicians offer attic insulation and abatement services in Anaheim, CA and the surrounding areas. Call Home Comfort USA today to learn more about what we can do to improve the air that you and your family breathe every day!
If you need a furnace repaired or an air conditioner serviced, we'll send a local technician out to diagnose the specific problem and recommend solutions for you and your family. There will be a diagnostic fee for the visit, and any specific repairs will be an additional charge. If replacing your system is the best solution, the fee for the diagnosis will be credited toward the purchase and install of a new system.

Nerthlings Heating and Air Conditioning is proud to be rated as Erie, PA’s leading heating and cooling company. We’ve been serving Erie PA and the surrounding areas for over 60 years, handling all of their HVAC needs. For furnace repair, furnace service, or a new heating system installation at your home/business, Nerthling’s is the company to call if you want the job done right. We are also experts at AC repair, service & installation, as well as generator installation. Our other services include boiler repair and service, geothermal HVAC, heat pumps and ductless heating & air conditioning. To learn more about our high-quality HVAC services, give us a call today at 814-240-2297!

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