Understanding Whole-House Ventilation Systems and Their Advantages and Disadvantages

One of the keys to creating a healthy home environment is proper ventilation. Without sufficient air movement, residents are more likely to be exposed to allergens, mold, radon gas and other contaminants.

That is why homeowners should take steps to improve air ventilation inside their homes. While there are many ways to increase the volume and quality of air moving throughout a home, the best way to improve ventilation is to install a whole-house ventilation system.

This guide offers more information about whole-house ventilation and includes an explanation of two commonly used options, as well as an examination of the advantages and disadvantages of each system.

Exhaust Ventilation

The simplest type of whole-house ventilation is exhaust ventilation. In an exhaust ventilation system, a strategically located exhaust inside the home pulls air out of the home and into the atmosphere. The exhaust fan is usually placed in the attic with an exhaust vent leading to the rooftop.

Depending on the sophistication of the system, the exhaust fan may be connected to a network of air intake ducts located throughout the house. However, it is also common for a single exhaust fan to be installed with no connecting ductwork.

Exhaust ventilation systems function by pulling fresh air through tiny cracks and crevices found throughout the home’s structure. In some instances, passive air vents are installed to aid in the intake of fresh air, especially if the structure is exceptionally well-insulated.

Supply Ventilation

Another widely used whole-house ventilation system type is supply ventilation. Supply ventilation systems function in an exact-opposite manner than exhaust ventilation systems. Instead of pulling air out of the home, supply ventilation systems push fresh air into the home.

Supply ventilation fans are also commonly found in the attics of homes and use roof-mounted air intakes. As with exhaust ventilation systems, the efficiency of a supply ventilation system can be increased through the use of ducts located throughout the home. The ducts enable fresh air to be better distributed and provide balance for the overall ventilation effort.

Since fresh air is pulled into the home through the supply fan, the “stale” air inside the home is pushed out through minute openings located all over the structure. Passive vents can be installed to increase the volume of air exhausted from the home if the home’s insulation characteristics make it necessary.

Advantages and Disadvantages Considered

Several factors should be evaluated before a decision is made about which whole-house ventilation system is best for a particular home. Both exhaust and supply ventilation systems possess advantages and disadvantages, and knowledge of each can help make the choice easier for homeowners.

Temperature and Moisture Concerns

Exhaust ventilation systems perform best in areas with cooler, dry climates. In warm, moist climates, exhaust ventilation can introduce humid air into the interior spaces between walls and cause mold or wood rot.

However, in cooler climates, supply ventilation systems can create problems by forcing heated interior air into attics, basements or other cold spaces. This action may cause condensation to form in these areas, which can lead to moisture-related damage inside structures.

Outside Air Quality

Another consideration when deciding what type of whole-house ventilation system to install is outside air quality. Poor air quality due to pollutants can make exhaust ventilation a bad choice for homeowners. These systems may draw contaminated air into the home and negatively affect the health of occupants as a result.

Supply ventilation can also present the same problem if the air drawn into the home through the fan is polluted. However, supply ventilation systems can be equipped with filters which will strip contaminants from the incoming air, and although such filtration will likely increase the cost of the system, it will overcome the difficulties associated with unfiltered air being passed into the home.

Appliance Ventilation

Whole-house ventilation can affect the operation of combustion appliances such as hot water heaters and furnaces. These appliances, fueled by natural gas, propane or oil, depend upon neutral or positive air pressure for proper operation. Positive air pressure occurs whenever interior air is at a higher pressure level than the air immediately surrounding the home.

However, negative air pressure can adversely affect the elimination of potentially deadly byproducts like carbon monoxide. In some extreme cases, negative air pressure can cause a backdraft of some of these byproducts back into the home where they can cause illness or even death.

If your home is equipped with combustion appliances, it’s most likely that the best choice for whole-house ventilation is a supply ventilation system. Supply ventilation creates positive interior pressure, which can help eliminate the possibility of backdrafts.

For questions about whole-house ventilation, be sure to contact the experts at Ragan Mechanical for help. The professionals at Ragan Mechanical understand the need for effective interior ventilation and can assist you in achieving this result.

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