Since the 1980s, manufacturers of HVAC equipment have been making an effort to make the systems they manufacture more efficient. This was originally driven by rising energy costs, and has more recently been driven by increased awareness of environmental issues. Additionally, improvements to the HVAC system efficiency can also help increase occupant health and productivity.[23] In the US, the EPA has imposed tighter restrictions over the years. There are several methods for making HVAC systems more efficient.
Some of the research I have done suggests to have your ducts cleaned when you first purchase a new home to remove drywall dust. Maintain your system well and you shouldn't have to do it again until you want to sell. Those are the two times cleaning was suggested. So for peace of mind maybe it is a good idea to do it even if you buy a used home and then maybe every 5-10 years.
1). Busy companies: The company is so busy, it doesn’t need the work. It will add 70% to 100% profit, and if the customer accepts the estimate, it will move that high-margin customer to the front of the line. This often happens in the worst heat of summer when overburdened ACs and heat pumps quit and the dead of winter when furnaces give up. This is a good reason to consider pre-emptively replacing your system once it’s about 15 years old and/or has had major repairs.

So, the total price to a contractor for this project is $7,195.77 (Carrier is expensive), which we’ll use to calculate a fair HVAC installation cost. As I said, we typically use 40% in the industry to cover our own personal profit, as well as our insurance and other expenses. Let’s take a look at page three of a Final Report from our own online HVAC calculator, the HVAC Design & Consultation Program.
You may consider having your air ducts cleaned simply because it seems logical that air ducts will get dirty over time and should be occasionally cleaned. Provided that the cleaning is done properly, no evidence suggests that such cleaning would be detrimental. EPA does not recommend that the air ducts be cleaned routinely, but only as needed. EPA does, however, recommend that if you have a fuel burning furnace, stove or fireplace, they be inspected for proper functioning and serviced before each heating season to protect against carbon monoxide poisoning.
On the other hand, if family members are experiencing unusual or unexplained symptoms or illnesses that you think might be related to your home environment, you should discuss the situation with your doctor. EPA has published the following publications for guidance on identifying possible indoor air quality problems and ways to prevent or fix them.
Despite such anecdotal experiences, there's no scientific evidence that regular residential air duct cleaning improves air quality, according to a 1997 brochure published by the Environmental Protection Agency. Laureen Burton, senior scientist in the EPA Indoor Environments Division, says that while the document is nearly two decades old, the science hasn't changed and the agency stands by its recommendations.
Some of these components can be repaired or replaced by the homeowner, such as filters, fuses, and clogged up drain lines. Coils, compressors and the other components are best left to a professional. In some cases, you may have a system that is so old that parts are no longer available or else they aren't up to code. In this case you will have to consider replacing the entire system.
Your HVAC unit and air ducts deliver heated or cooled air throughout your home year-in and year-out. The air your HVAC unit produces travels through your ductwork and heats or cools your home via the air vents in each room. The dust and other particles in your home’s air are known as particulate matter, which the EPA defines as "a complex mixture of extremely small particles and liquid droplets." The EPA also notes that "particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles." Having clean air ducts means fewer of these particles moving through your home. If you remove your furnace filter and hold it up to the light, you can probably see several hundred of these minuscule particles floating in the air. 
All of the products discussed above are registered solely for the purpose of sanitizing the smooth surfaces of unlined (bare) sheet metal ducts. No products are currently registered as biocides for use on fiber glass duct board or fiber glass lined ducts, so it is important to determine if sections of your system contain these materials before permitting the application of any biocide.
Our Fort Smith, Arkansas area restoration services are available at your convenience. We provide emergency services after devastating property damage and work hard to restore and clean as much of the contents and structure as possible. We'll Work With You and Your Insurance Company to cover costs and expedite the process. If you need cleaning and restoration services or are looking for ways to create a healthier, more efficient environment, contact McMahon's Cleaning & Restoration, LLC to get started.
The EPA is so far behind on useful knowledge because of the lack of funding so don't be mislead. The Hvac old timers were left at the dock so to speak and missed out on the IAQ movement. The ones that are savvy and up to date on the information do Air Duct Cleaning, even tho that will lead to a few less service calls its the right thing to do for their customer. Please take a look into a return duct that has never been cleaned, I dare anyone to say it does not need to be cleaned.
Excalibur Water Systems helps solve the water challenges around the globe with water solutions for any possible water concerns in: water hardness, filtration of any contaminant, bacteria removal and high purity water needs and also comes with a warranty of up to 20 years at no extra cost. The best warranty for the water treatment equipment industry.
DIY: We don’t recommend a DIY approach. Depending on the system, working with gas, electricity and refrigerant create dangers. Beyond that, it is essential that split system components be selected for compatibility. DIY installation of an HVAC system will void the warranty of most brands. The manufacturers won’t stand behind the warranty when anyone other than a certified installer does the work. This is true since improper installation is the main cause of poor system performance and mechanical breakdowns.
Mitsubishi Electric is a world leader in air conditioning systems for residential, commercial and industrial use. Challenged to create air conditioning systems that provide exemplary performance in the wide-ranging climatic conditions found throughout Japan, our engineers develop amazingly sophisticated yet durable units and systems capable of constant use under virtually any natural climatic condition on earth.
I always get a laugh at anyone claiming to be in the business for any length of time that doesnt understand the importance of cleaning out a ventilation system. Not only for better indoor air quality but for maintaining your heating equipment. I guess it makes more sense to some people that the furnace will just run better with a ton of dust and debris and maybe this wont be a big cause of sytem breakdown and malfunction. I mean really? Maybe this guy got a bad company and or cleaning and is a little jaded but to advise cleaning your grills , which does nothing, and replacing a filter....come on guy.
These factors are included in a "Manual J" calculation. Contractors who make these calculations before recommending a size can take a couple of hours collecting the information and making the calculation. If your contractor doesn't do it, there are services that will do it for around $99. If you're feeling particularly on the ball, there are also free online calculators.
I am a service technician [since '92].....and as to double filtering.....I have never recommended it. Granted.....it would be noticeably helpful if the fiberglass filters are the main ones used [which I also never recommend.....as long as system can deliver appropriate air flow with a pleated cotton filter...and any decent service tech can check the air flow for proper cfm]. Any particles small enough to pass through a pleated cotton filter are going to pass through a second filter as well....unless the second filters are so tight that the system is starving for air flow. Has anybody ever accidentally put two filters in their automatic drip coffee maker? What if cars used two fuel filters or air filters? I have told some homeowners to try using second filters at each register [the black thin filter material cut-to-fit....same type used in many window air conditioners].....but I only suggest this when I know they will still get at least 400 cfm per ton of air flow [350 absolute minimum]......as some homeowners know others who say it has helped and it gives them a peace of mind knowing they are doing something to help contribute to a solution, so it HAS to help [even though I think it falls in the "one-born-every-minute" category.....similar to duct cleaning].

The liquid refrigerant is returned to another heat exchanger where it is allowed to evaporate, hence the heat exchanger is often called an evaporating coil or evaporator. As the liquid refrigerant evaporates it absorbs energy (heat) from the inside air, returns to the compressor, and repeats the cycle. In the process, heat is absorbed from indoors and transferred outdoors, resulting in cooling of the building.


Since the 1980s, manufacturers of HVAC equipment have been making an effort to make the systems they manufacture more efficient. This was originally driven by rising energy costs, and has more recently been driven by increased awareness of environmental issues. Additionally, improvements to the HVAC system efficiency can also help increase occupant health and productivity.[23] In the US, the EPA has imposed tighter restrictions over the years. There are several methods for making HVAC systems more efficient.

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.
Pay particular attention to cooling coils, which are designed to remove water from the air and can be a major source of moisture contamination of the system that can lead to mold growth. Make sure the condensate pan drains properly. The presence of substantial standing water and/or debris indicates a problem requiring immediate attention. Check any insulation near cooling coils for wet spots.

I know it has to have a new concentric venting system installed, I believe it needs new plenums ( mine are rusty but both of these require extra work , so someHVAC persons are saying I do not need either!! RED FLAG THERE. Also, it will need a new drain using PVCP ?? Piping run maybe two, depending on where my evep coil drain is conected (here in TN they use to run them in with the septic lines, now they cannot be run through that way), Lastly I am not where or what these things do beides hold water but I was told It needs a filter rack and new filter base safety pan. THATSSS it that is all I know about this stuff aside from the fact that nothing up there is to code thus far LOL. !!
Had our ducts cleaned late April, 2016. Sodium Chlorite was sprayed into ducts after cleaning. Ever since, we have been bothered with eye and nasal passage irritation because of a “chemical” and “musty” odor. This odor is present whether or not a/c is on.) We are told the sodium chlorite (“EnviroCon, manufactured by Bio-Cide International) is used in hospital and nursing home settings and is not hazardous to health. The air duct company’s suggestion is that they come out and spray even more sodium chlorite…we absolutely don’t want this done! Have had various other recommendations about what we need to have done to remedy our problem. We will be unable to stay in our home if a resolution cannot be found. We’d be willing to replace the ductwork if necessary. (One professional suggested that the cleaning may have “knocked something loose” inside the ductwork and that is the source of the irritant.) This home was built in 1920…no idea when the present ductwork was installed. Any suggestions would be appreciated.
After major damage to a small addition on our home was damaged in the windstorm in May, the insurer’s preferred vendor sanded drywall without taping off the area. They relied on heat from the furnace to dry the mudding compound. They claimed they shut the furnace off while sanding and regardless of whether they did or not, they never cleaned up the drywall dust before turning the furnace back on. I now have drywall dust everywhere and my husband took photos to verify our concerns. They even sanded right above a cold air return. Vents were never covered either. The same company that created this mess is cleaning my ducts today. They have refused to clean the furnace. Their are health concerns for my almost 85 yr old mother who resides with us. I’ve tried 3 times in the last 7 days to escalate to a manager and they will not return my call. They just keep sending it back down to my adjuster. There are many other issues we’ve encountered since May as well. This is a major insurance company who has the resources to fix this mess but refuse. Please help!
2. If air quality is so important and duct cleaniliness is so uncertain, why not adopt doubling filtering; that is, in addition to the existing main furnace filter, add a filter at each air outlet. I understand replacing so many filters would be a burden, but air outlets can be designed for easy filter replacement. The builders and home design engineers should bear responsibility to provide good and low maintenance homes, rather than prioritizing on fancy or costly featuers for homes.
I live in a 1950's ranch house in the South. The prior owners were smokers. Based on recommendations from one of the local conservation organizations, I decided to have a home energy audit done. As part of their findings, they recommended additional insulation in the attic and duct cleaning and sealing. This turned out to be a very problematic process. In terms of the ducts, it was necessary to remove the metal grates. However, these grates had been painted over many times and shoe molding covered the bottom of the grates. The vendor was not able to remove the grates without damaging them in the process. Because these grates dated back to the 1950's, it was difficult to find appropriate replacements. The ones I finally discovered were correct except they were 1/4" wider. This meant that the shoe molding had to be carved out. The duct cleaner could not provide any assistance with this problem. It took me a month of long evenings replacing the vent covers myself, carefully chiseling out the shoe molding and repainting. In terms of the extra installation in the attic, the same vendor used blow in insulation. Unfortunately, they did not recognize that the 13 floodlights whose mounting extended into the attic were not designed to be buried under insulation. The problem manifested itself in terms of expensive flood light bulbs failing continually. So, I had to have all of the light housings replaced. Yet another unexpected expense. Despite the expense, pain and suffering, I cannot report any improvement in my heating costs or the "quality" of the air. To be fair, I do not have any allergies and did not undertake this for air quality improvements but rather heating efficiency improvements.
Your HVAC unit and air ducts deliver heated or cooled air throughout your home year-in and year-out. The air your HVAC unit produces travels through your ductwork and heats or cools your home via the air vents in each room. The dust and other particles in your home’s air are known as particulate matter, which the EPA defines as "a complex mixture of extremely small particles and liquid droplets." The EPA also notes that "particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles." Having clean air ducts means fewer of these particles moving through your home. If you remove your furnace filter and hold it up to the light, you can probably see several hundred of these minuscule particles floating in the air. 
I just had my Air ducts “cleaned”. The person who came to my house works for an air duct cleaning company who uses a professional vacuum. He said the company would charge me about $900 but he can do it aside on his own and charge me half of that. However, when he came over the house, he brought the rotary brush along with his domestic vacuum cleaner that it’s hose was about 5 feet long, I ask him that the wasnt strong enough to pull dust out, and he said, it’s similar to what companies use. I was in doubt and he didnt cover the vents so im thinking all dust must have come out from every air vents. Could this vacuum have taking the debris out of the air ducts? Or how can I myself find out if the inside of the air ducts have been cleaned and no debris is sitting there? I have dust all over my house.
These factors are included in a "Manual J" calculation. Contractors who make these calculations before recommending a size can take a couple of hours collecting the information and making the calculation. If your contractor doesn't do it, there are services that will do it for around $99. If you're feeling particularly on the ball, there are also free online calculators.
Those of you who read our posts regularly know that we built our reputation as a U.S. Veteran-Owned business that prides ourselves on giving people straight, honest answers to their questions...and there’s no question that makes people cringe more than asking, what does a new HVAC installation cost? Oddly enough, most contractors keep their air conditioning installation cost a closely guarded secret, as if the knowledge of how much it should cost will somehow change your decision when you have to buy a new AC. What I will tell you, is that the fair price of an HVAC installation will vary greatly based on the type of heating and air conditioning system installed, as well as the options needed or desired (Ductwork included? Zoning system?). In this article, we’ll discuss the five system features that affect HVAC installation cost, fair price ranges you can expect to pay for your new system, we will then perform an example calculation of how you can calculate a fair price, and finally, what you can do to keep from getting ripped off on your new HVAC installation price.
This company deserves more than five stars. They didn't just replace my heater and air conditioner, they built me a new system for my house. Going above and beyond is a understatement. Steve's staff were 2 of the nicest workers I've come across in a long time. Friendly, knowledgeable, and very clean. Truly a top rated company. Thanks Steve.   Great job.
Alberto said they were busy but could either install on the upcoming Saturday.  We were going to be out of town and said unfortunately that day did not work.  He then proposed the upcoming Tuesday as a possible solution, but just had to confirm with another appointment.  I said great.  I will review the estimate and call your office to confirm I want to move forward with the install.
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.
20 yrs ago I bought the house I am in and a Central H/A was installed at that time. At the beginning of ea season I have the unit serviced. Every yr since I have owned the house I have had to have freon added and been told that I must have a freon leak. Fast forward to this yr when I hired a new company to do the service. They went up into the attic as part of their overall servicing. Nobody else has ever done that. He came down showing me pics on his camera phone of ducts that were not even connected to anything and in my estimation have probably been laying there for 20 yrs. Of course he fixed this. I have not needed freon this year either. I have been complaining to friends about the huge amount of dust and how I can't keep up with the cleaning away of it for a long time. Now it makes so much sense.To me it is like that duct work was just up there laying around and every time my unit was blowing, all the insulation, debris, dust and whatever else over the years was just randomly filling up those ducts. What now that they are re-connected? Will it be better? Or am I someone that needs to have my ducts cleaned? I am so confused after reading all these comments. Can one of you experts tell me what you would do before I spend a bunch of money that I don't really have? Thank you for any input you can provide. Also, feel free to respond to email address denise@digitalflak.com
Had duct cleaned (apartment) however, dust is still settling throughout the apartment. Contractor said no other cleaning necessary until two (2) years. Is there a time period before dust no longer settles prior to that time? Should the vendor had worn a mask? He did not cover his face the vents and dust was blown throughout the apartment (had family help with the cleanup). I had to leave when they left because I have asthma and I couldn’t breathe without coughing. Please help!
I can’t believe I got ripped off by this Air Duct Cleaners. I called them for this $63 coupon per furnace unlimited vents then when they came after he checked it all I hear is I have molds and leak all is worth $499, $799, $899 per furnace but I told him to just clean the duct and patch the single leak per furnace worth $38 each. Still eanding $899 total. All the work he done is in less than an hour he didnt even go to each vent to clean it. All he did is to path the air leak on that entry pipe to the furnace and open the main venting system, vacuum it, and wash the floor of the vent with a solution. Overall time is about 20 mins talking with me discussing all the option which thinking they made me think I don’t really have an option and 40 mins wash and vacuum he took pictures of before and after of only one furnace. He gave me a receipt without the details on what he has done in the house just the name and price. I think we may need a strict law to punish and control all this companies who do this so other company who do good will despise them.
While you consider having your air ducts cleaned, it is a good idea to take a look at your dryer vent. If your dryer vent is clogged, you could be losing energy efficiency. Worse yet, you could be increasing the risk of a house fire. Having your dryer vent professionally cared for costs about $130 on average, and could save you a bit of money and a lot of headaches in the future. For more information on the benefits and cost of having your dryer vent cleaned, take a look at our comprehensive cost guide.
Very interesting article. I searched articles about services for cleaning ventilation systems. But I have some questions. For cleaning ventilation system used special products for cleaning. Can I know in company manager about, which type of cleaning products they use? Your family members may be allergic in some components. It’s very big problem. And one more problem it’s how to choose the right company in Internet. Sometimes I don’t have much time to find a company in my town and I use the Internet. But I find a lot of company. It is very popular services, for example, Stanley Steemer – https://www.stanleysteemer.com/ or my local not very popular service, for example, AllstatesAirDuctPro – http://allstatesairductpro.us/. Can I understand the company is professional or not, only looking through the website? What must I check on the website? Who has helpful information? I will very grateful for your help. Links I add for understanding my problem. They are random and not for advertising.
The answer to your question is most likely "Yes," but not defiitely. It depends on where the dust is coming from. Now, if your house is more than say, 12 years old then you likely do have leaks in your ducts that can let in insulation particles and dust from your attic. If this is the case then cleaning of the ducts-PROPER CLEANING, which like the article sas doess include EVERYTHING that the conditioned air passes through, such as your indoor evaporator coil and blower housing assembly-is definitely a good first step to getting that dust under control! Of course I highly recommend that you also have your ducts SEALED as well, or else you will have to repeat the cleaning some time down the line. As a 3rd step, consider an electronic air filter. I always thought they were a scam, personally, so I never bothered selling them to my clients. Then one day my manager sent me to install one for a senior couple in a mobile home. The wife had bad allergies, and her eyes were constantly watering and puffy and red. Well, I did a quality check 60 days later and she could not stop praising that air filter! Keep in mind that in a mobile home, duct seals are not as complete as those in other homes due to access issues.
Energy efficiency can be improved even more in central heating systems by introducing zoned heating. This allows a more granular application of heat, similar to non-central heating systems. Zones are controlled by multiple thermostats. In water heating systems the thermostats control zone valves, and in forced air systems they control zone dampers inside the vents which selectively block the flow of air. In this case, the control system is very critical to maintaining a proper temperature.

Natural ventilation is the ventilation of a building with outside air without using fans or other mechanical systems. It can be via operable windows, louvers, or trickle vents when spaces are small and the architecture permits. In more complex schemes, warm air is allowed to rise and flow out high building openings to the outside (stack effect), causing cool outside air to be drawn into low building openings. Natural ventilation schemes can use very little energy, but care must be taken to ensure comfort. In warm or humid climates, maintaining thermal comfort solely via natural ventilation might not be possible. Air conditioning systems are used, either as backups or supplements. Air-side economizers also use outside air to condition spaces, but do so using fans, ducts, dampers, and control systems to introduce and distribute cool outdoor air when appropriate.


Asbestos removal tip.  Don’t trust any HVAC installation company that says that they will remove asbestos for you. They will do either one of two things: remove it and do a horrible job because they don’t know how (an illegal act in California, finable by up to $250,000), or they will say they did and never actually do it, which is dangerous to your health. Any HVAC contractor worth their weight will know not to touch it. Call an asbestos abatement company – it should cost around $500-$1,000, and your HVAC installation company will come in right after them and do the installation to decrease cost and inconvenience.
A do-it-yourself approach will only scratch the surface because it is hard to reach some of the ventilation running underneath the floor or into the wall. Although it may help in clearing some of the dust and debris, you really need a professional to guarantee your system is truly spotless. The proper procedure involves the use of a powerful vacuum system with multi-brush attachments designed to loosen debris and feed into the suction. Particles are then blown outside of the house or passed through a HEPA filter inside.

Within the construction sector, it is the job of the building services engineer to design and oversee the installation and maintenance of the essential services such as gas, electricity, water, heating and lighting, as well as many others. These all help to make buildings comfortable and healthy places to live and work in. Building Services is part of a sector that has over 51,000 businesses and employs represents 2%-3% of the GDP.


AC installation in Fort Smith, AR is vital to comfort, safety, and quality of life. The region is infamous for the unbearable heat that can often become debilitating. This is why investing into an AC to improve the overall lifestyle of your family is well worth the cost. Avoid the constant frustration by seeking the assistance of a professional team.
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.
I am NADCA Certified Air Systems Cleaning Specialist. Over the year I have learned on simple answer to this questions: there air duct cleaners and there are pretenders. There will be no benefit at all if you use on the very cheap pretender because they will not really clean anything. On the other hand if you call a qualified air duct cleaner with a NADCA Certification you will, like 99% of my customers, report improvement with your respiratory problems, you will see less dust and the job will pay for itself with energy savings and repair prevention.
Vinick calls air duct cleaning an essential part of home maintenance, akin to mopping and vacuuming. "It’s like changing the oil in your car,” he says. “If you don’t change the oil, you’re going to have a problem. When your components are loaded up with debris, the system has to work harder. When you remove that debris, you get energy consumption savings.”

Indoor Fan Motor -- Indoor fans circulate the air from your house and through the system. Age and dust buildup are the two biggest contributing factors to their failure. When they are starting to fail they will often make noise. Failure of the fan will result in no heating or cooling, and if it is not repaired soon, it can cause other components to fail.

Our unit is 16 years old and we've had it checked out recently since it seems to be running excessively. Over all the tech says it is putting out well; it's the correct size, we have no shade and we've been having extreme heat with high humidity. The info you provided is very helpful and will help us make an informed decision when the time comes. Thank you so much.


Monday the following week, no phone calls, or follow up.  I call to get an update and am told that they cannot install my system because they don't have time.  I ask what does that mean, one year? One week? Until the end of summer they say.  What does that mean I ask?  They say at the end of September.  I say thank you for wasting 1 month of my time.


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.
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.
The most recognized standards for HVAC design are based on ASHRAE data. The most general of four volumes of the ASHRAE Handbook is Fundamentals; it includes heating and cooling calculations. Each volume of the ASHRAE Handbook is updated every four years. The design professional must consult ASHRAE data for the standards of design and care as the typical building codes provide little to no information on HVAC design practices; codes such as the UMC and IMC do include much detail on installation requirements, however. Other useful reference materials include items from SMACNA, ACGIH, and technical trade journals.
Bigger is not necessarily better when it comes to HVAC systems, and smaller isn't always more efficient. If you have too small of a system, your system will be running constantly as it tries to keep up with the temperature. If you have too large of a system, it won't run long enough to keep up with the humidity. In order to handle both temperature and humidity efficiently, an HVAC system should run for around 30 minutes at a time. If your system is staying on too long or shutting off after only around 10 minutes, you are not getting efficient performance.
Knowing what you should be paying for your HVAC equipment and installation is essential to getting a fair deal. Most HVAC prices aren’t advertised. Contractor strategy is to get a salesperson into your home to sell you on a package of equipment, accessories and installation. This makes comparing systems difficult, and some sales pressure might be applied.

Equipment used to clean ducts varies widely. The cheaper the equipment used the more you are just wasting money. This is why it's typically not worth doing. In some situations it may be beneficial, but only after determining and investigating the duct system. This should be done by a licensed HVAC contractor and not a duct cleaner that typically do not hold and HVAC license. (Duct cleaners aren't required to be licensed in HVAC in many areas.)
You may be familiar with air ducts that are constructed of sheet metal. However, many modern residential air duct systems are constructed of fiber glass duct board or sheet metal ducts that are lined on the inside with fiber glass duct liner. Since the early 1970's, a significant increase in the use of flexible duct, which generally is internally lined with plastic or some other type of material, has occurred.
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