Air duct cleaning service providers may tell you that they need to apply chemical biocide to the inside of your ducts as a means to kill bacteria (germs) and fungi (mold) and prevent future biological growth. They may also propose the application of a "sealant" to prevent dust and dirt particles from being released into the air or to seal air leaks. You should fully understand the pros and cons of permitting application of chemical biocides or sealants. While the targeted use of chemical biocides and sealants may be appropriate under specific circumstances, research has not demonstrated their effectiveness in duct cleaning or their potential adverse health effects. No chemical biocides are currently registered by EPA for use in internally-insulated air duct systems (see Should chemical biocides be applied to the inside of air ducts?).
The AC contactor (relay) and start/run capacitor(s) (see illustration below) fail most often and are inexpensive. So it's a safe bet to buy and install those parts right away, especially if your air conditioning service unit is older than five years. The condenser fan motor can also fail, but it runs about $150 — hold off buying that unless you're sure that's the culprit.
We are all getting migraines several times a month. I have asthma but not ever as bad as it has been and my 2 year olds dr just informed me she potentially has asthma too. We all get sinus infections regularly and eczema and contact dermatitis. None of us have been this way until recently in our apartment. A roof leak with mold was repaired recently mold was sealed off not removed. We also had lead paint removed from a few window trims this year. I wasn’t here to see if they covered the vents. We had mice too. I vacuum everyday we have hardwood floors no one wears shoes past the font door and I’m getting over a cup full of dirt every time I vacuum. Dust on everything daily. White dust. It’s a 4 room apartment with 1 intake. They are filthy from what I can see when I change the filters. The filters are black after a few months. I feel bad to ask the homeowner to get the system cleaned, can’t afford to move (we live in the city & it’s expensive). I am going to try the shop vac to remove what I can. Any experienced hvac people please give your opinion. Should I just get it done and pay for it myself? We have lived here for 13 years. It’s never been cleaned since ive been here. Is it something I can do with a shop vac? Can i use a wet rag to get the powder dust on the inside of the vents off. One vent has what looks like chunks of dry wall or thick paint sitting in the vent and none of the vents screw into the wall, the screws just fall out. No one ever reinforced the area so the wall just basically crumbles. Kind of useless to spend the money on filters since the air and dust just blows out around the sides of the vents and one of the vents just falls right out of the wall when the heat is turned on. I don’t know why the owner doesn’t fix it. He’s been here to replace filters and saw the condition.
The Chartered Institution of Building Services Engineers is a body that covers the essential Service (systems architecture) that allow buildings to operate. It includes the electrotechnical, heating, ventilating, air conditioning, refrigeration and plumbing industries. To train as a building services engineer, the academic requirements are GCSEs (A-C) / Standard Grades (1-3) in Maths and Science, which are important in measurements, planning and theory. Employers will often want a degree in a branch of engineering, such as building environment engineering, electrical engineering or mechanical engineering. To become a full member of CIBSE, and so also to be registered by the Engineering Council UK as a chartered engineer, engineers must also attain an Honours Degree and a master's degree in a relevant engineering subject.
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,
I turned on the AC when he was finished and immediately saw black fuzz balls the size of marbles come out of several of the registers. He said that was expected since everything was shaken up. So much for describing the service as cleaning. I paid him and sent him on his way. I cannot imagine that this type of service is worthwhile in anything but a new house. Apparently in old houses such as mine I can expect that using a whole house humidifier in the winter followed by a great AC can loosen the soot. Maybe this is to be expected for the first few weeks of summer each year. I now have lined the inside of the registers with cheesecloth to catch the fuzz. I’ll see if it stops after a couple of weeks.
Brands like American Standard, Trane and Lennox cost the most. Goodman is the cheapest. The rest populate the middle of the spectrum. Here’s something to know: The quality among brands isn’t as great as price differences. The difference in prices reflect that some customers want “bargain” equipment to save cost and others want “premium” equipment they believe will run longer with less trouble. Therefore, each manufacturer has priced to meet consumer perception.
Fuses -- Anyone who has worked with electrical systems knows all about fuses and how they fail. They can burn out over time, may just be loose, or can blow out during an electrical storm or due to overload from another failed component. Of course, that's what they're supposed to do; they stop surges from going through and damaging the rest of the system. When a fuse fails, whatever system it was protecting will stop working.
Humidifiers/Dehumidifiers: Humidifiers add needed moisture to the air in winter and very dry climates. Dehumidifiers remove dampness any time of the year. Central air conditioners dehumidify too, but in very humid climates, you might want to remove humidity without also cooling the air. You have a good range of options for both of these HVAC accessories. Whole-house humidifiers cost $350 to $800 installed, while dehumidifiers are $1,250 to $2,000 or slightly more.
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.

And if you have flex duct and/or fiberglass ductboard in your home- the last thing you want is a big brush or anything abrasive running through it. Even high-pressure air can erode ductboard so I wouldn’t clean it with anything. If it becomes contaminated, get rid of it and install real ductwork. If your ductwork is accessible in the basement – the best thing to do is take it down and manually clean it if it’s full of junk. It’s not going to cost a nickel more to do that than to pay $500-1000 for a ‘duct cleaning machine” AKA big blower and vacuum – to do the job.

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.
As a homeowner and an owner of rental property I can tell you that the air ducts sometimes need to be cleaned. If you have had pets or anyone smoking in your home (even a visitor) for any length of time, having the ducts cleaned is really good idea. I had a tenant who did not smoke, but got married to a smoker more than year after moving in. When I realized someone was smoking I had them move out, but the smell was awful. I had the ducts cleaned and sanitized (it was a bit extra). The ducts were shiny like new afterwards. I left the windows open for a few days and we cleaned the place super clean and then replaced the carpets. The duct cleaning was worth every penny because the house looked, smelled, and felt new afterward. I plan to have my own house ducts cleaned again this year as we have two cats. We had them cleaned about 12 years ago and they found building materials in the ducts! If you move into a house that has never had them cleaned, it is good to do it. If you have allergies, clean the ducts to see if it helps. You never know what is in your ducts if you have never had them cleaned.
When these aren't properly maintained and sanitized, they can build up dust, pollen, and even mold. This means when the air conditioner or heater turns on, the spores are released into the air for you to inhale. While some are less harmful, people who have allergies or sensitivity to certain spores will react negatively. Plus, mold is dangerous for anyone to ingest and should be avoided by regular maintenance.
My heat pump/hvac system is not blowing cold air anymore, got checked out was told compressor broken. was told it cost  almost the same to repair/replace they recommend whole system. It's the same company that installed it 18 years ago, telling me that system is old and it will cost $9-10k for new system, because furnace has to be replaced with new hvac. what to do, need answers thanks????
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.

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.
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.
Metal is way better than flex duct or ductboard. It gets better airflow, holds up to critters and duct cleaners. I know of no hvac company here that cleans ductwork. (there probably is one somewhere) The mfg's of duct cleaning equipment keep trying to sell us hvac people on their benefits and profit potential but most all hvac people know that unless you have metal ductwork you are NOT doing the customer any favors.

In modern buildings, the design, installation, and control systems of these functions are integrated into one or more HVAC systems. For very small buildings, contractors normally estimate the capacity and type of system needed and then design the system, selecting the appropriate refrigerant and various components needed. For larger buildings, building service designers, mechanical engineers, or building services engineers analyze, design, and specify the HVAC systems. Specialty mechanical contractors then fabricate and commission the systems. Building permits and code-compliance inspections of the installations are normally required for all sizes of building.
HVAC services is our go to contractor when it comes to our HVAC needs. Back in 2013, we were dealt some unforeseeable home projects, as our  HVAC was failing and needed to replace the whole system, e.g. Furnace, Blower, A/C, Condenser, Vents, etc... We reached out to a few HVAC companies (Contra Costa Heating and Air, EP builders, High Performance Heating and Air) so we could compare the bids for the job. We have had some issues with past contractors and after thoroughly screening a few of the above mentioned HVAC contractors, we awarded the bid to HVAC services because of their superior customer service and very reasonable pricing.

An AC contactor is a $25 mechanical relay that uses low-voltage power from the thermostat to switch 220-volt high-amperage current to the compressor and condenser fan. AC contactors can wear out and are at the top of the list of common air conditioning service failures. Even if your AC contactor is working, it pays to replace it every five years or so. Unscrew the old AC contactor before removing the wires. Then move the wires to the new unit (Photo 6).
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