In the United States, HVAC engineers generally are members of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), EPA Universal CFC certified (for installation and service of CFC HVAC devices), or locally engineer certified such as a Special to Chief Boilers License issued by the state or, in some jurisdictions, the city. ASHRAE is an international technical society for all individuals and organizations interested in HVAC. The Society, organized into regions, chapters, and student branches, allows exchange of HVAC knowledge and experiences for the benefit of the field's practitioners and the public. ASHRAE provides many opportunities to participate in the development of new knowledge via, for example, research and its many technical committees. These committees typically meet twice per year at the ASHRAE Annual and Winter Meetings. A popular product show, the AHR Expo, is held in conjunction with each winter meeting. The Society has approximately 50,000 members and has headquarters in Atlanta, Georgia.
Next check and clean the furnace’s flame sensor. The video below shows you how—note that this guy fixes it in about 5 minutes. We would probably use a little bit of emory paper, but he cleans the sensor with a 5-dollar bill. Another video further down the page under the discussion of “If your furnace keeps shutting off after about 5 minutes” shows the same project with a different brand of furnace.
A pinging or popping sound coming from the duct work can come from thermal expansion—the ductwork expanding and contracting as it heats and cools.  Or, air blowing past a loose flap of metal can make the sound. Track along the duct runs, listening for the sound. If you locate it, make a small dent in the sheet metal to provide a more rigid surface that’s less likely to move as it heats and cools.
Your HVAC professional can also help you verify that your system is properly matched by providing you with an AHRI Certificate of Certified Product Performance upon request. The certificate verifies that the outdoor unit (condenser) and the indoor unit (evaporator) combination has been certified as a matched system by the Air Conditioning, Heating and Refrigeration Institute (AHRI). For higher efficiency systems, this certification may help you obtain a rebate from your utility or local municipality if you have to replace your unit in whole or in part. Not all areas offer a rebate, but your technician will likely be able to provide information about the certification process. Fees for performing this certification vary, but generally are relatively inexpensive.
American design standards are legislated in the Uniform Mechanical Code or International Mechanical Code. In certain states, counties, or cities, either of these codes may be adopted and amended via various legislative processes. These codes are updated and published by the International Association of Plumbing and Mechanical Officials (IAPMO) or the International Code Council (ICC) respectively, on a 3-year code development cycle. Typically, local building permit departments are charged with enforcement of these standards on private and certain public properties.
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.
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.

At Aire Serv, we’re on call 24/7 to offer air conditioner repair when you need it most. We charge by the job, not by the hour, and there’s never an overtime charge. We explain all your options before starting repairs so you can decide what’s best for you. Our air conditioner repair experts are licensed and insured, and we guarantee our work the first time around. Since we service and repair all equipment brands, you can put your full confidence in us to professionally complete your AC repair.
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.
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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