I have worked cleaning HVAC in my area for almost 5 years. I always do a thorough inspection and cleaning, providing before and after photos. I have completed some jobs where I felt that it was not entirely necessary, but ultimately what the customer wanted. With that being said, I have endless photos of unspeakable horrors. Hotels are usually nasty, post construction mess is certain, pets and kids create lots off debris, bugs congregate and die, then spiders set up and die, I have even had one supply that was nearly plugged with sand!
HVAC System Quality Installation Contractor Checklist -- This checklist identifies all of the steps the contractor has taken for the Energy Star Certification and identifies what work the contractor has done. If the system is later modified, this checklist can help identify what was done to proper Energy Star specifications and what was added later that may not meet the requirements.
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.
I read your article with interest and think it is a good start. One service that is always talked about is fogging ductwork for sanitizing. Many companies offer this service for disinfecting or adding a clean smell to the ductwork. Before any chemical or disinfectant is used, please read the MSDS (Material Safety Data Sheet). You might be surprise on what you are putting into the air stream. This is a high profit service and should be explored thoroughly before purchasing,
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.
The cost to replace a central air conditioner is about $5,000. However, this price varies depending on the size of your home and the difficulty of the project. It can cost as much as $12,500 to replace an AC unit. The labor required to remove and dispose of the old system adds to the price. The size of your home, brand of AC unit and ductwork complexity can all raise the cost as well.
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.
Air conditioning and refrigeration are provided through the removal of heat. Heat can be removed through radiation, convection, or conduction. Refrigeration conduction media such as water, air, ice, and chemicals are referred to as refrigerants. A refrigerant is employed either in a heat pump system in which a compressor is used to drive thermodynamic refrigeration cycle, or in a free cooling system which uses pumps to circulate a cool refrigerant (typically water or a glycol mix).
My point is that the brand of equipment you choose is going to affect your HVAC installation cost greatly. People often call us for an air conditioning installation job and say, “I would like to install Carrier equipment.” Now, if you are a future client of ours, I’ll have to warn you – I can be a bit of a smart-ass. Why can’t work be fun? Besides…I was in the Navy for 11 years, what do you expect. 
All modern air conditioning systems, even small window package units, are equipped with internal air filters. These are generally of a lightweight gauze-like material, and must be replaced or washed as conditions warrant. For example, a building in a high dust environment, or a home with furry pets, will need to have the filters changed more often than buildings without these dirt loads. Failure to replace these filters as needed will contribute to a lower heat exchange rate, resulting in wasted energy, shortened equipment life, and higher energy bills; low air flow can result in iced-over evaporator coils, which can completely stop air flow. Additionally, very dirty or plugged filters can cause overheating during a heating cycle, and can result in damage to the system or even fire.
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.
Sounds like your first hvac company was ripping you off. Ask your new company to go to your coil and see if there is a leak. If there isn't the last company was just lining their pockets. If you have had ducts unhooked for a long time I would recommend duct cleaning, trust me I'm not a fan of duct cleaning myself. I have done hvac for 20 yrs. in GA. When I just bought a home built in 1996, we had all the ducts replaced immediately.

My mom just received service from this company. She paid $609 to have her frion replaced. After two uses the AC stops working. A young rep comes out to the house again and notifies her that her entire AC unit and furnace need to be replace for just shy of ten grand, though when her frion was refilled she was told that her system should last another five years. When they came back to tell her how her entire system needed to be replaced, they were generous enough to offer her a $300 credit on the nearly $10,000 estimate of replacing the entire system that was working fine until they touched it. My best assumption would be that there is a mishap with the system is due to their negligence. Id suggest using another company other than these scam artists.
Demonstrate visible evidence of microbial growth in your duct work. Some service providers may attempt to convince you that your air ducts are contaminated by demonstrating that the microorganisms found in your home grow on a settling plate (i.e., petri dish). This is inappropriate. Some microorganisms are always present in the air, and some growth on a settling plate is normal. As noted earlier, only an expert can positively identify a substance as biological growth and lab analysis may be required for final confirmation. Other testing methods are not reliable.
NADCA and EPA both have good points. Although, organizations are made to make money. Common sense and looking at NADCA and EPA pre-checklist. If you don't see it in the check list, you don't have to do it! But, if you do, look up Diamond certified co.s and the BBB. Beware of bait and switch scams, $60 vents and the like coupons which claim to help all for the measley sum of $79.00 bucks.
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
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:
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.

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.
Yes everyone should get all their ductwork cleaned, because it does help, incame down with major allergies and had serval operations on my sinues because of this problem of air quality and dust, plus i almost died from one of the operations, i was suffering so much. Yes you can seal your duct system by buyind duct seal t instead of tape to tape all the corners of the vent system, tape wears out and gets brittle, the sealant you can buy at home depot, and you just brush it all over the connections of your ductwork, it comes in a container and it is like a thick paste and dries making a good seal for your ductwork.
I just bought a home, and the sellers clearly never had the air ducts cleaned. This is, unfortunately, typical of their neglect of the home, so I am not surprised. I was cleaning around the wooden floor registers, and I took the registers off. I found nests of some sort...all kinds of really gross stuff!! I am calling now to schedule duct cleaning for my new home. Anyway, it is very easy to check to see if you really need duct cleaning. Remove the floor registers and use a flashlight if necessary to see if there is dust or debris in the ducting. If these look bad, I'd definitely have the system cleaned. I would also do it after a construction project, after installing a new furnace, etc. I have found that once I had my previous system cleaned, it seemed to remain spotless for 3 years. So it seems that if you just change your filters on time (I have an iPhone alert set for every 3 months), the system will stay clean for years. Hope this helps!
The HVAC installation costs below are based on residential installations only, and are priced for a single unit. Two units should be about twice the price. “Tim, shouldn’t there be a discount?” If people start giving you discounts, they are probably charging you too much to begin with.  That’s our philosophy anyway. Twice the parts and time should be twice the price from a fair contractor. The prices listed include component parts (with warranty), labor, and all materials for a complete HVAC installation.
The cooling coils the air comes into contact with appear to need UV-C lights on them in humid climates. That's the biggest thing. If the ducts have never been cleaned, then getting that done goes without saying. But those coils need to be cleaned, disinfected, and then UV-C light(s) installed to prevent mold & bacteria build-up in the future on them. That appears to be chiefly responsible for the dirty laundry and/or sour milk smell coming from forced-air AC systems in humid regions.

The HVAC installation costs below are based on residential installations only, and are priced for a single unit. Two units should be about twice the price. “Tim, shouldn’t there be a discount?” If people start giving you discounts, they are probably charging you too much to begin with.  That’s our philosophy anyway. Twice the parts and time should be twice the price from a fair contractor. The prices listed include component parts (with warranty), labor, and all materials for a complete HVAC installation.
Internal insulation provides better acoustical (noise) control. Flexible duct is very low cost. These products are engineered specifically for use in ducts or as ducts themselves, and are tested in accordance with standards established by Underwriters Laboratories (UL), the American Society for Testing and Materials (ASTM), and the National Fire Protection Association (NFPA). Many insulated duct systems have operated for years without supporting significant mold growth. Keeping them reasonably clean and dry is generally adequate. However, there is substantial debate about whether porous insulation materials (e.g., fiber glass) are more prone to microbial contamination than bare sheet metal ducts. If enough dirt and moisture are permitted to enter the duct system, there may be no significant difference in the rate or extent of microbial growth in internally lined or bare sheet metal ducts. However, treatment of mold contamination on bare sheet metal is much easier. Cleaning and treatment with an EPA-registered biocide are possible. Once fiberglass duct liner is contaminated with mold, cleaning is not sufficient to prevent re-growth and there are no EPA-registered biocides for the treatment of porous duct materials. EPA, NADCA and NAIMA all recommend the replacement of wet or moldy fiber glass duct material.
You and your family spend hours sitting on your favorite chairs, couches and sectionals. Over time, dander and body oil become trapped in the upholstery, but with regular cleanings you can keep these delicate fabrics looking, feeling and smelling great. We examine your furniture and select the best process to safely clean and protect any kind of upholstery, including leather. 
Installation: The old furnace is disconnected from the ductwork plenum, exhaust flue, gas and electrical hookups. In most cases, a new plenum must be made onsite or ordered from a local sheet metal fabricator. A new vent might be required too. The furnace is set and reconnected. Adjustments to the blower fan speed and burner are made to optimize furnace performance for your home and climate.
I guess I should present my credentials first, I am a 30 year veteran of the heating and cooling industry. I started at the bottom and have participated in every area of the trade. Installer, service, maint. Ownership, rep, territory manager and so on. A forced air duct system is a large vacume. Like your vacume it has an air intake (return air) and an exhaust (supply registers). A filter just like a vacume (located next to furnace or air handler). Now I want you to visualize something. Put your head inside your vacume cleaner and breath. Get the picture? This is what your duct work looks like. Do you clean your vacume when it’s dirty? If it’s full and the filter is dirty you lose performance and it starts poluting the air you breathe. It’s common sense. I recommend hiring a duct cleaning outfit that you have researched to be honest, background checked, drug tested, insured, and highly recommended by your piers in the area. The service is a necessity, but like everything, it should be done by a qualified company.

Indoor Coil -- The indoor coil is a heat transfer device. It absorbs the heat from the inside of the house and passes it on to the refrigerant and is pumped outside. Dust that builds up on the coil can hamper its ability to absorb heat. High heat transference coils use very thin metal. Airborne chemicals can cause corrosion which leads to leaks. The constant vibration of the compressor can also cause solder joints to weaken and leak. An indoor coil may operate for weeks with a tiny leak, and you may not notice the loss in performance right away. As soon as a leak is made known, it should be replaced or repaired immediately.
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.
I am NADCA Certified Air Systems Cleaning Specialist. Over the years 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.
The use of furnaces, space heaters, and boilers as a method of indoor heating could result in incomplete combustion and the emission of carbon monoxide, nitrogen oxides, formaldehyde, volatile organic compounds, and other combustion byproducts. Incomplete combustion occurs when there is insufficient oxygen; the inputs are fuels containing various contaminants and the outputs are harmful byproducts, most dangerously carbon monoxide, which is a tasteless and odorless gas with serious adverse health effects.[14]
Free cooling systems can have very high efficiencies, and are sometimes combined with seasonal thermal energy storage so that the cold of winter can be used for summer air conditioning. Common storage mediums are deep aquifers or a natural underground rock mass accessed via a cluster of small-diameter, heat-exchanger-equipped boreholes. Some systems with small storages are hybrids, 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-in because the storage acts as a heat sink when the system is in cooling (as opposed to charging) mode, causing the temperature to gradually increase during the cooling season.
fact is most homes have bad filter racks. when you insert the filter it doesn’t seal well to the sides so some of the air and dust bypass it and end up in the supply ductwork and into the house. Most of the dust in the supply ductwork settles down and doesn’t get blown in the house but some of it does when the blower starts up or when you put a new filter. If you have allergies or other health problems put in an electronic air cleaner, get your ducts cleaned and run the fan as much as you can afford. you can also get an ECM motor installed which is going to be worth it if you want to run the fan 24/7. If you have uninsulated metal ducts take down the ones you can and wash them. Then put them back and seal the joints. Cleaning the ductwork also improves airflow which is important to AC and Heat pump systems for efficiency. An electronic air cleaner will also improve airflow and static pressure because they usually have a much larger filter surface area. An electronic air cleaner also keeps the ac coil clean like new which means better efficiency and no cleaning needed. AC furnaces sometimes grow mold around the coil because of the condensation. Electronic air cleaners should be able to filter mold spores but the best remedy is installing a UV light next to the coil which will kill the mold.
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.
The next step was cleaning the cold air returns. He found a good spot to drill an 8” hole for his vacuum hose. The procedure matched the other air ducts except that when he finished at the two cold return registers he drilled several holes in the cold ducts in the basement and blasted air into them. Because of our houses age and the upgraded return system, I noticed that the main sheet metal return duct had no top but was just butted up against the ceiling in the basement. When he blasted air in, dust and crap shot out the edges along the ceiling. Once he finished that he removed the filter and “swept” out anything at the bottom of the return with his hand into the 8” hose.

Compressor -- Compressors are outdoor components in your system. The compressor is the pump that circulates the refrigerants through the air-conditioner. You can hear it when it's running so you'll know if it's working just by listening. If it starts getting louder, your compressor is about to fail. If it makes no sound when it should be on, it has already failed. Compressors fail for a number of reasons. Most often they fail due to strain from another failed part such as the fan motor. Electrical storms can also damage compressors. If the sound from the compressor gets louder or if you see a decrease in performance, you should have your compressor checked. A failed compressor will not heat or cool your house.
HRV/ERV Ventilators: These whole-house ventilators exchange air. They are ideal for homes with what is called a “tight envelope,” homes where house wrap has been applied and airgaps in the attic, around windows, doors and outlets have been sealed. Air in these homes becomes stale and polluted, so exchanging the air is important to IAQ. Heat recovery ventilators (HRV) are designed for cold climates. Energy recovery ventilators (ERV) are best for warm climates.  Your cost for an installed HRV or ERV will range from about $2,000 to more than $5,000 based on its capacity and features.
Pro HVAC company Southern Comfort Mechanical says on its blog, “If there’s mold growth inside the handler due to excess moisture, algae in the condenser drain line or a dirty evaporator coil, it can negatively impact your AC unit’s efficiency. The filters inside may also build up excess dirt and become clogged, which will also make your AC [or heat pump] waste energy trying to sustain the cool climate inside your home.” These issues are easy to solve. They don’t require replacing the air handler.
The Antimicrobials Information Hotline provides answers to questions concerning current antimicrobial issues (disinfectants, fungicides, others) regulated by the pesticide law, rules and regulations. These cover interpretation laws, rules and regulations, and registration and re-registration of antimicrobial chemicals and products. The Hotline also provide information health & safety issues on registered antimicrobial products, product label and the proper and safe use of these antimicrobial products.
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