The bottom line is: no one knows. There are examples of ducts that have become badly contaminated with a variety of materials that may pose risks to your health. The duct system can serve as a means to distribute these contaminants throughout a home. In these cases, duct cleaning may make sense. However, a light amount of household dust in your air ducts is normal. Duct cleaning is not considered to be a necessary part of yearly maintenance of your heating and cooling system, which consists of regular cleaning of drain pans and heating and cooling coils, regular filter changes and yearly inspections of heating equipment. Research continues in an effort to evaluate the potential benefits of air duct cleaning.
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.
If you are replacing your air conditioning system, make sure that the unit is the proper size for your needs and that all ducts are sealed at the joints. A unit that is too big will cycle on and off frequently, resulting in poor moisture removal, particularly in areas with high humidity. Also make sure that your new system is designed to manage condensation effectively.

If there is stuff in the ducts, the fact that it’s laying there and not being blown into the rooms is proof positive that it is hurting no-one. The 5-6 exceptions you cite in this article I’ll buy, but only with the caveat that at least some of those could have been avoided by proper protection (during remodeling for example) – and if asbestos/lead/whatever winds up in your ducts- the remodeling contractor should be the one paying to remove it.
When water damage strikes, you need to act quickly. Time is of the essence. We're available 24/7 to dispatch trained, certified crews, equipment and inspection tools specializing in water damage. With our national footprint and large coverage areas throughout the country we will arrive on site and begin work quickly, minimizing the damage to your home. 

Typically speaking, the lower SEER, more basic models are also more reliable.  Reliability is big with us, so we steer clear of features with reliability issues, and it’s as simple as that. When you factor in the price of repairs and the extra expense of the 21-SEER, you may actually lose money! 16 SEER is the sweet-spot, and it is key to reducing your HVAC installation cost.
Important Tip: Don’t just pay attention to the high-end of the price range! – which is what I know you are all looking at, but also look at the low range. If a contractor is cheaper than this, ask “why?” Usually it is because they don’t have liability insurance, workman’s compensation insurance, are unlicensed, all of the above, or worst yet, they don’t use HVAC technicians. You are spending a lot of money.  Make sure that they are licensed (In California, check here at CSLB License Checker) and insured.

A BTU is the amount of energy required to heat or cool one pound of water by one degree Fahrenheit. So a 1-ton air conditioner can cool 12,000 pounds of water by one degree every hour. That’s all it means, so don’t let yourself be lost in jargon! How this affects your HVAC installation cost is that the larger your house is, the more tons will be required to heat and cool it.


In variable climates, the system may include a reversing valve that switches from heating in winter to cooling in summer. By reversing the flow of refrigerant, the heat pump refrigeration cycle is changed from cooling to heating or vice versa. This allows a facility to be heated and cooled by a single piece of equipment by the same means, and with the same hardware.
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]
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 think that the coding and permit industry is a joke!! They will not allow the homeowner to apply for the permit it has to be the licenced contractor. It would make since to allow the homeowner to apply for this. But it is all about money!! They really don't care if its up to code because if they did then they wouldnt care who applied and payeed for it, but they want the contractor to do it so if they do something wrong they can fine them instead of just pointing it out and allowing them to do it right.

Heating, ventilation, and air conditioning (HVAC) systems have been shown to act as a collection source for a variety of contaminants that have the potential to affect health, such as mold, fungi, bacteria, and very small particles of dust. The removal of such contaminants from the HVAC system and home should be considered as one component in an overall plan to improve indoor air quality.


Contact/Relay -- Relays are electronically controlled switches that activate the various components of your HVAC system. They manage everything from the power going to the motor to automatic dampers, humidifiers, etc. Most of them are controlled by the thermostat. The most common failure for a relay is being stuck in the "open" position. Separated from its assigned contact point, it fails to complete the connection and send the message to whatever it was supposed to operate. This failure usually occurs from use over time. Each time a relay connects and sends its signal, the electrical arcing from point to point eventually causes wear and tear.
My vent covers have lots of mildew. They look bad! I live in a very humid climate in a condo. The handyman here has offered to take those down, wash them, sand, & then spray paint them with a mildew resistant paint. He said that he will leave them off overnight to dry. I am wondering if this is safe to breath the AC blowing out into the open all night??. ! Guess it is better than the mildew!?
On the other hand, if a service provider fails to follow proper duct cleaning procedures, duct cleaning can cause indoor air problems. For example, an inadequate vacuum collection system can release more dust, dirt and other contaminants than if you had left the ducts alone. A careless or inadequately trained service provider can damage your ducts or heating and cooling system, possibly increasing your heating and air conditioning costs or forcing you to undertake difficult and costly repairs or replacements.
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