So, naturally I respond with, “you don’t tell your doctor which medication to prescribe you, do you?” The point is, on the residential level, who you get to install your HVAC unit is far more important than which unit you choose.  Keep your options open and let your HVAC contractor make a few recommendations – that’s why you spent time finding a reputable contractor!
If you are replacing your air conditioning system, make sure that the unit is the proper size for your needs and that all ducts are sealed at the joints. A unit that is too big will cycle on and off frequently, resulting in poor moisture removal, particularly in areas with high humidity. Also make sure that your new system is designed to manage condensation effectively.
The HVAC industry is a worldwide enterprise, with roles including operation and maintenance, system design and construction, equipment manufacturing and sales, and in education and research. The HVAC industry was historically regulated by the manufacturers of HVAC equipment, but regulating and standards organizations such as HARDI, ASHRAE, SMACNA, ACCA, Uniform Mechanical Code, International Mechanical Code, and AMCA have been established to support the industry and encourage high standards and achievement.
There are many interesting comments from several informed individuals. The question that has not been answered is how do duct systems get dusty and dirty? As a RESNET Home Energy Rater, I perform pressure tests on homes and duct systems, and the one common thread is . . . most air delivery sytems have large amounts of air leakage. The solution is to seal the duct system, and pay particular attention to the return duct system and ductwork near the air handler (the 'blower'). As others have said, a captive (sealed) duct system with proper filter maintenance should be more then adequate for most occupants. For those who have allergy, asthma, or other breathing problems, a filter with a higher MERV rating (number should be listed on the package) or a HEPA filter are good choices. These filters will capture smaller particulates and should improve the indoor air quality. Again, make certain that the entire duct system is sealed, preferably with mastic, second choice UL-181 foil tape - never use cloth duct (also known as duck) tape.
On the other hand, if a service provider fails to follow proper duct cleaning procedures, duct cleaning can cause indoor air problems. For example, an inadequate vacuum collection system can release more dust, dirt and other contaminants than if you had left the ducts alone. A careless or inadequately trained service provider can damage your ducts or heating and cooling system, possibly increasing your heating and air conditioning costs or forcing you to undertake difficult and costly repairs or replacements.

They were quick to come out and diagnose the problem with my furnace, but I thought the estimate of $549 a bit high to replace the circuit board.  So called around and found Leo's Appliance in Concord that sells appliance parts and the circuit board was only $90.49 - that is the retail cost to me, so I imagine the wholesale cost is a lot less.  So BEWARE of this company since they wanted $500!!! to replace the circuit board which is located right in the front of the furnace - extremely easy to access.  I hate it that you cannot trust repair companies.
Maybe I took him to literally but I am pretty sure cops wont show up to ensure that my duct gets replaced. He said it would be over 1000 dollars to replace the ductwork if that is the case. Now, I spoke to a friend who did 2 ductwork lines on his own in his attic and he said it was like 15 dollars for the plastic wirewound tubing to create new ducts. Should I cancel that appointment and just do the work on my own? I feel like I’m a chump or lazy for considering paying someone to do this work.

Here in Atlanta we get 6 to 10 $49 coupons in the mail weekly…I have always consider them a complete scam….just had my master bathroom& bedroom and guest bath completely remodeled down to the studs…Had my 3 returns nearest the area sealed to prevent sheet rock dust to spread…it worked and I personally cleaned all 7 returns when a 5 HP , new Rigid shop Vac($99 from HD)…took one hour and I found little evidence that “I need my ducts cleaned” Had quotes from $400 to $600…I use the best air filters for my air handler and change it every 2 to 3 months…..any dust is trapped in it and I believe the Air Duct folks are all cons….
Furnace Circuit Board -- The furnace circuit board controls a variety of functions. It not only handles the regular operation of the furnace, it also monitors the furnace's various safety circuits. Over time, vibrations from the furnace can weaken solder point and cause them to separate. Dirt and debris can cause short-circuits that damage the board. Failure of the circuit board can cause a variety of effects ranging from the fan not turning on to the complete shutdown of the furnace.
To find companies that provide duct cleaning services, check your Yellow Pages under "duct cleaning" or contact the National Air Duct Cleaners Association (NADCA) at the address and phone number in the information section located at the end of this guidance. Do not assume that all duct cleaning service providers are equally knowledgeable and responsible. Talk to at least three different service providers and get written estimates before deciding whether to have your ducts cleaned. When the service providers come to your home, ask them to show you the contamination that would justify having your ducts cleaned.
An EER certifies the cooling efficiency of HVAC units. It's calculated by the rate of the cooling in British thermal units (Btus) per hour and divided by the rate of energy input in watts at a specific temperature. The calculation goes as BtuH/WATT at dry bulb (db) versus wet bulb (wb) temperatures. The optimal rating for a cooling unit is about 80db/67wb inside and 95db/75wb outside.
One problem occurred on Monday.  When we called at 2:30 in the afternoon to check on status, we were told that "the tech is on the phone with the parts supplier now".  It seems more likely that they had forgotten about us and our call woke them up.  But even if true, why the heck did they wait until 2:30 to order the part?  Maybe if they had ordered it in the morning they could have had it the same day.  So I'm taking off one star for that.
An EER certifies the cooling efficiency of HVAC units. It's calculated by the rate of the cooling in British thermal units (Btus) per hour and divided by the rate of energy input in watts at a specific temperature. The calculation goes as BtuH/WATT at dry bulb (db) versus wet bulb (wb) temperatures. The optimal rating for a cooling unit is about 80db/67wb inside and 95db/75wb outside.

Duct cleaning has never been shown to actually prevent health problems. Neither do studies conclusively demonstrate that particle (e.g., dust) levels in homes increase because of dirty air ducts or go down after cleaning. This is because much of the dirt that may accumulate inside air ducts adheres to duct surfaces and does not necessarily enter the living space. It is important to keep in mind that dirty air ducts are only one of many possible sources of particles that are present in homes. Pollutants that enter the home both from outdoors and indoor activities such as cooking, cleaning, smoking, or just moving around can cause greater exposure to contaminants than dirty air ducts. Moreover, there is no evidence that a light amount of household dust or other particulate matter in air ducts poses any risk to health.
Deciding if central air is worth the cost depends on your needs and local housing market. If you live in a hotter climate, it can definitely be worth the price. Not only can it keep your home at a comfortable temperature, but air conditioning can even save lives during extreme heat waves. But in a milder zone without severe temperatures, window units, fans or the breeze from an open window could be adequate.

I originally took off one star because of the SNAFU with getting the part ordered.  When Alberto called me on the phone he admitted the person had "gotten busy with other things" and apologized.  THAT was taking the high road and I was impressed by that.  Sadly, for reasons I won't guess at, Alberto has decided to take the low road in his comments and imply that they got the part as quickly as possible.  Well, we called at 2:30 so did someone spend six and a half hours finding the part??  That seems very doubtful.


To qualify for a tax credit from the federal government, you must save the manufacturer's certificate from your system. The IRS won't require the certificate at the time you file your federal tax forms, but they recommend keeping it with your records in case of an audit. It proves that you purchased a qualifying product. The government offers tax credits for:


Our HVAC Ductwork Installation Cost Guide is the most comprehensive guide of its type. It fully explains the purpose of ductwork and all your options. Pricing is included for all duct types and plenums/drops too. Material and installation costs are listed. Ductwork cost varies greatly by the size and type of duct plus the complexity of the installation, but you can expect to pay $10.20 to $17.25 per linear foot installed.

I am 79 years old, bought a condo & spent a lot of money on it. this winter my first bill was 450.00. had my furnace checked out, which is on the roof. it was old rusted out & leeking oil. i talked to owner & had new unit installed. they came out to clean ducks & they were split & worn out. there is no crawl space because theres a unit above me. my real estate lady or this company will not help me fix this problem.

The short answer is yes, duct cleaning, done right by a reputable company will help with the smell. It is likely though the smell is coming from another source, ie the crawl space. It could also be that another rodent is dead in the duct work. A visual inspection would be in order to check for any breach in the duct system. A duct pressure test would be able to tell you how much air is leaking from the system over all. A hole large enough for an animal to enter would loses a great deal of air, over 300 CFM. It would be worth looking into having this test done and it should cost around $200. Cleaning the air handler and evaporator coil will greatly improve the performance of the air conditioner. Dirt and dust on the evaporator acts as insulation and reduces the amount of cooling done be the coil. Any quality duct cleaning should include cleaning the air handler and coil, and the tech should allow you to watch him perform the work as it is done.
An air conditioning system's SEER is especially important if you live in a climate that changes temperature dramatically. The SEER is determined by the cooling output during the winter divided by its electric input during the winter. The higher the rating, the more efficient it will be. In January of 2006, the U.S. put standards in place for cooling units which are still in effect today. They must have a minimum SEER of 13. So, if you live in a home with a system installed before the new standards went into effect, consider having it replaced. SEER 13 units increase home efficiency by 30 percent.

Multiple inventions within this time frame preceded the beginnings of first comfort air conditioning system, which was designed in 1902 by Alfred Wolff (Cooper, 2003) for the New York Stock Exchange, while Willis Carrier equipped the Sacketts-Wilhems Printing Company with the process AC unit the same year. Coyne College was the first school to offer HVAC training in 1899.[12]


This article was very good. It should be noted that the EPA building in Washington, DC, was cited years ago as one of the worst "sick building syndrome" buildings. Wish you had mentioned about having people's dryer vents cleaned since they can cause so many fires in homes. Most homeowners forget to check the air flow on the dryer vent. Our company, which cleans by NADCA standards, does both air ducts and dryer vents. Thanks again for keeping the public informed, especially regarding the cost of air duct cleaning...you get what you pay for...don't be fooled by the lowest cost out there. Frequently these are bait and switch companies or will keep adding on features they say a customer needs until the price is so high it's ridiculous.
HVAC professionals in the US can receive training through formal training institutions, where most earn associate degrees. Training for HVAC technicians includes classroom lectures and hands-on tasks, and can be followed by an apprenticeship wherein the recent graduate works alongside a professional HVAC technician for a temporary period.[33] HVAC techs who have been trained can also be certified in areas such as air conditioning, heat pumps, gas heating, and commercial refrigeration.[34]
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).
Capacitors -- Capacitors help your HVAC motor start from a standstill. Over time they can weaken. As they weaken, they cause the motor to run hotter. This can shorten the life expectancy of your motor. Once a capacitor fails, the whole motor will stop working. You usually won't notice that a capacitor has weakened until your motor stops turning on.

WELL, this summer when I opened them up we had black dust spewing from one of the upstairs vents. It resembled the fuzz that comes off new towels. This prompted us to look into duct cleaning. We heard from someone who had it done several times, said it was worthwhile, and knew of a firm that did a good job. Clean Air America sent a single technician for the appointment and after counting registers and ducts gave me a price of $360.00 which included “sanitizing” the system (a $99 additional fee per can used). The small size of the plenum forced him to connect the 8” round vacuum hose from the truck to the 10” square opening from our humidifier unit. In hindsight, a mistake since it reduced the “negative” pressure in the system.
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]

Air duct cleaning service providers may tell you that they need to apply a chemical biocide to the inside of your ducts to kill bacteria (germs) and fungi (mold), and prevent future biological growth. Some duct cleaning service providers may propose to introduce ozone to kill biological contaminants. Ozone is a highly reactive gas that is regulated in the outside air as a lung irritant. However, there remains considerable controversy over the necessity and wisdom of introducing chemical biocides or ozone into the duct work.
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