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 microscoptic dust particles.

Research by the EPA has demonstrated that HVAC system cleaning may allow systems to run more efficiently by removing debris from sensitive mechanical components. Clean, efficient duct and vent systems are less likely to break down, have a longer life span and generally operate more effectively than dirty systems.

There are two methods of duct and vent cleaning. One system is connected into the ducting to provide suction. A high pressure air hose is passed through the ducting to remove the particles from the interior. The other system uses a large specialized vacuum attached to a hose and a brushing system that is run through the ducting. Both systems are effective when operated by properly trained personnel.

A proper cleaning should include the following: cleaning of all registers, inside the ducting, and the interior of the heating and ventilating system. The furnace fan must be cleaned and if you have air conditioning or a heat pump, the coils inside the system must also be thoroughly cleaned. Finally, a disinfectant can be fogged through the cleaned system to eliminate any mold, bacteria and dust mites that might remain. Proper cleaning of a home should take a minimum of three to five hours, depending on the size of the house. If the home has more than one heating and cooling system, or the system is located on the roof, it can take longer. Most duct cleaning companies base their price upon square footage or the number of registers, systems and levels to be cleaned and charge between $90 - $125 per hour to properly clean a duct system.

If a much lower price is offered, a consumer needs to make sure that the price includes a thorough cleaning, including registers, the inside of the ductwork and all the fans and coils. Charging extra for cleaning fans and coils is unreasonable because those steps are mandatory for having a properly cleaned system.

-- Tips courtesy of HomeAdvisor.com