Refrigerant Metering Device -- Every HVAC system has one of these, and heat pumps have two. They regulate the amount of refrigerant going through your air-conditioner. If it fails, either too much or too little refrigerant will course along the lines and either not perform well or will overwhelm the compressor and cause it to fail. A total failure of this component will result in a complete loss of operation.
My 48 yr old house (mine for the last 4 yrs) has considerable dust in the return plenum (fiber duct). I’m remodeling and recently re-sealed the return plenum AND the site-fabbed transition built when the new unit was installed, 2013. The return was leaky no doubt drawing musty, dusty air from the crawl space due to the Red-Neck fab & seal job! Pitiful craftsmanship! It took me 7 hours to fix the new transition piece. Anyway, the dust in the house is the same “color” as whats in the return duct and I’m getting way too much & too often in the house. I’ve also cleaned my coils, which were not that dirty.
Whether or not central air adds value to your home depends on your location. You probably won't recoup the entire cost for the installation, as it is an expensive project that isn't as flashy as something like a new deck. But this invisible upgrade can help you sell your home if you live in a hot climate. And many buyers are willing to pay a bit more for a working AC.
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.
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.
I was told that 15 out vents would be cleaned and one main vent. the guy came over and gave me an estimate of $500. I had acquired a groupon for $49. the guy said just doing the out vents and one main vent would accomplish nothing. Now I am in dispute with the groupon people for a refund which they won’t give and have to go ahead and waste the money and let them do it. Is their doing the 15 outvents and one main one going to accomplish anything?
Heating, ventilation, and air conditioning (HVAC[1]) is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation, as HVAC&R or HVACR or "ventilation" is dropped, as in HACR (as in the designation of HACR-rated circuit breakers).
He proceeded to clean each heat register by removing the grille and blasting it with an air pressure hose toward the duct opening thinking that the dust would magically be sucked inside. In one room this caused a ceiling smoke detector to go off because the excess dust fooled it into thinking there was smoke. I put my hand in front of a register he wasn’t working on and could hardly feel a suction. Although we discussed how I open and close damper doors, I realized later that he never checked, opened or adjusted them during the cleaning. He could have closed all but the one he was working on in order to increase suction results. His next step was to blast air into the duct and then attach a “squid-like” device that slapped around inside the duct as far as he could reach. This is important! In a newer house, ducts have long straight runs from the furnace. In older houses like mine they can turn and twist. In fact, the duct we have a problem with runs straight up from the basement inside a wall and turns 90 degrees into a soffit for three feet then into two 90 degree turns to get into the floor joist area for another two feet and finally a 90 degree turn up to the second floor register. When he cleaned this one he could only get three feet into the register with the hose or squid because of the turns. That was the case with most. Hardly what could be described as a decent cleaning.
I agree that good filtration and a sealed system will prevent the need for duct cleaning. However, when we do get called it is because the duct work has reached a noticeable state of restriction or dust or the homeowner is hyper-sensitive to these pollutants in their home. Most of the time we find that no filter or a cheap (99 cent) filter is being used or they have serious duct leaks in the system. If you are hiring a cleaner make sure they are using professional cleaning equipment which will consist of a rotating brush system and a vacuum source. Be highly skeptical of the contractor with no branded system or the guy who shows up with just chimney brushes and a shop vac. He will not be able to reach around all the corners or all the runs in your system and he will be taking your money for a superficial cleaning at best. Only trust a company that offers VIDEO inspection and more importantly.... a contractor who repairs, installs and seals ducts if a problem is discovered or heaven forbid, created. Good luck and get your ducts sealed if you do have a leak! It is one of the greatest energy losses to a home other than being poorly insulated.
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,
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.

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.

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.
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,
Furnace cleaners are mostly young men, I know this, I have been one for 15 years or so……so heres the truth, if there are any allergies, children, older people with health issues, we are GOING to make money. do not tell the company you have hired about any health complication. they are salesmen. and they don’t care about you. or your money. make sure they do a good job, then kick them out. you don’t need all the bells and whistles they wanna sell you. any idiot can clean duct work, like I said, I am one of them. I am very good at it, but I don’t have the back bone to sell a widowed old lady a humidifier that she doesn’t need for 500 bucks, overall, if you think you need this service done, which you probably don’t, get it done, do not spend anything over 300$ and do not do it again for at least ten years.

DIY: Most DIY installations go smoothly. The major brands have compatibility checkers to see which of their models will work with the wiring your old thermostat is using. Potential problems involve the need for a C-wire, or common wire, when the existing bundle doesn’t include one. There are solutions discussed in our Thermostat Buying Guide, linked to below.

 The A/C System Cleaning and restoration industry has become a very lucrative bait and switch industry that many Carpet cleaning companies, Maid services, as well as plumbing or handyman service companies are adding on to there services. These add-ons are not fully certified, trained or even have any experience in the HVAC industry. These companies are the reason prices and quality of work are all over the place. If you are looking to make a smart decision for your home a professional Duct Cleaning service will protect you for 5-7 years. This info comes from NADCA (National Air Duct Cleaning Association) which is the closest thing to a license we have for duct cleaning. They have a great site that explains this process and pricing much more in depth and factual than what has been written here. This organization is working very hard to get these bad companies exposed and out of this industry. So in saying that do your research! Green Duct Decontamination is a certified company with certified technicians that take this work very seriously. We can not have these low rated unprofessional companies paste a bad name for an entire industry. Stay away from anything under 250$ for a full duct clean this is not feasible, go look at NADCA.com and you will understand why and what these companies are doing to rob you of your dollar.
I believe a $3 [sic] pleated cotton filter is all that is ever needed to keep a system running top notch. A cleaning of the blower squirrel cage and of the evaporator [indoor] coil may be needed one time if fiberglass or no filters have been previously used. The return air grille [or grilles] need vacuumed off occasionally, as they are upstream from the filter. The $3 filter should be changed every 3 months [rule of thumb]....and most of them have a little white square on the cardboard frame to write install date.....and the arrow should point into the duct [if at filter grille]....or towards the furnace [if in ductwork slot]...or towards the blower [if in blower compartment]. My two cents.....
A dehumidifier is an air-conditioner-like device that controls the humidity of a room or building. It is often employed in basements which have a higher relative humidity because of their lower temperature (and propensity for damp floors and walls). In food retailing establishments, large open chiller cabinets are highly effective at dehumidifying the internal air. Conversely, a humidifier increases the humidity of a building.
Professional cleaning involves getting the dust and debris outside, so they use outdoor ventilation equipment. It is so important that homeowners make sure the professional contractor is using good equipment then, as they could otherwise spread the spores into the home and further agitate sensitive family members. In the case of mold, a cleaner will only be able to tell you it is there, followed by needing an additional mold professional to come out and test or remove the mold. Air duct cleaning industries do not require state licensing, so make sure to check for a company with references.
We moved to a house built in 1965 from a 1915 house with a dirt basement. Against what I anticipated, the 1965 house was much dustier. It was like felt on top of everything. I cleaned and cleaned and it did become less dusty over time. We then found out a cat lady with over 2 dozen cats lived in the house in the past. We then had to get our furnace replaced and I was able to look down some of the duct work, the dirt and debris was 3-5 inches deep. Additionally, the basement ducts were entirely plugged with debris including dirt, seeds, ants, toys, etc. I had already removed what I could from those. We had our ducts cleaned last year, and the dust in the house is greatly reduced. Also have lost the runny nose I got after moving here. There are duct cleaning con artists out there, but ours did a good job.
With the split system, the evaporator coil is connected to a remote condenser unit using refrigerant piping between an indoor and outdoor unit instead of ducting air directly from the outdoor unit. Indoor units with directional vents mount onto walls, suspended from ceilings, or fit into the ceiling. Other indoor units mount inside the ceiling cavity, so that short lengths of duct handle air from the indoor unit to vents or diffusers around the rooms.
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.
Heaters are appliances whose purpose is to generate heat (i.e. warmth) for the building. This can be done via central heating. Such a system contains a boiler, furnace, or heat pump to heat water, steam, or air in a central location such as a furnace room in a home, or a mechanical room in a large building. The heat can be transferred by convection, conduction, or radiation.

Greetings from Mama Duck from Ductz of Greater Atlanta. These are some awesome comments and a few are from high quality duct cleaners that I personally know. After 19 years in this industry I agree that a government agency is not always up to date with their knowledge but won't admit it. If they were out in the field with our technicians every day they would upgrade their info. I get calls all the time where customers have been taken advantage of by "go and blow" companies. The customers don't know what they don't know but many are too lazy to do the research and are just looking for cheap. The industry has gotten a bad rap due to these con artists but the customer has to take some responsibility. I ask them why they would want to do business with a company who lies to them in print? Are they stupid or just cheap? Thankfully there are those of us in the industry who are working diligently to raise the bar on quality, protect the consumer and perform high quality work. At Ductz all our technicians are NADCA certified, trained by the best in the industry and know how to clean the entire system.


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.
I took off stars for two reasons. Minus one star for issues trying to use the $50 for $25 voucher I purchased through Yelp. Although there was no minimum stipulated, the office wouldn't take it for the initial $59 diagnostic fee. If I used the 10% off First service that they offer, then they won't let me use the voucher on the actual repair bill.  I was stuck with paying the full $59 diagnostic fee.
I recently did some remodeling and figured I’d get the air ducts cleaned in our 12 year old home. After obtaining 4 estimates between $572 and a whopping $3,075 for 25 vents and 2 air handlers, I knew I was in for a ride. I read through this blog and decided to use a $79 inspection camera I just found online (Home Depot) to take a look at all my ducts by removing the ceiling grilles first and then try to get into the ducts from the other end. From what I have just learned here, I believe that will take care of my “concerns”.
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.
Roof-mounted systems have the heating and cooling systems in one cabinet. Sometimes called "gas packs" (if the heater uses natural gas), they typically cost less than a comparable split system. In dry regions, most homes originally had "swamp-coolers" installed. When replacing them with HVAC systems, it's often cheaper to use existing mounts and ducting.
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.
PickHVAC Tips: Don’t be sold on systems with features you don’t want or need. Called “upselling,” it is rampant in the HVAC industry. Some features are nice – if you want them. If your single-stage furnace was loud and pushed out cold air at the start of the cycle, then a two-stage model will improve those issues. If you didn’t notice them, the upgrade will be a waste of money. That’s just one common example.

Unfortunately, manufacturers and contractors don’t publish this information…it’s a secret. Why? Who knows…but we have access to a full contractor pricing database of 1,000’s of different units in our online HVAC installation cost calculator, so let’s choose one for our example calculation. We’ll go with Carrier equipment, since our readers always bother us about them (despite us telling them that they are overpriced):
i got angies list deal for 109 air duct clenaing, dryer vent cleaning, and furnace inspection, {healthy duct cleaning} i call the company, they arrive on time. did excellent service what ever i purches i got. they give me furnace inspection and the told me that my furnace is very dirty and they offer me to clean that for 250 extra. i paid and i am very happy from this service. i try before 2 diffrent company that i got deal from them as well the just give me estimate and don’t even do the job. so guys don’t spend time if you need deep cleaning just cal this guy the offer free estimate as well.
First of all, I think it is great that there are many companies out there who look out for the customer and protect their interest. Secondly, I think it is also important that customers consider having their HVAC systems checked thoroughly before moving into a new home. I have heard a couple of horror stories where previous owners have not had the best housekeeping skills. Even when the appearance of the home seems it has been well kept, keep in mind that surface clean only goes so far. You can never tell what lies underneath.

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.
If no one in your household suffers from allergies or unexplained symptoms or illnesses and if, after a visual inspection of the inside of the ducts, you see no indication that your air ducts are contaminated with large deposits of dust or mold (no musty odor or visible mold growth), having your air ducts cleaned is probably unnecessary. It is normal for the return registers to get dusty as dust-laden air is pulled through the grate. This does not indicate that your air ducts are contaminated with heavy deposits of dust or debris; the registers can be easily vacuumed or removed and cleaned.
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