Here are answers to some common questions.
1. How do you change an air filter?
Location: Modern central heating and air conditioning systems generally have the filter located as close to the blower unit as possible, in the cold air return duct. Remove the grill or box cover holding your filter in place.
Remove the dirty filter: Dispose of the dirty filter in a bag to contain the dirt.
Install: Install the new or cleaned and dried air filter with the air flow arrow pointing toward the blower. Record the date and wash or change the filter within the recommended period. If you experience higher dust levels in your home due to changes in outside air, construction or dry weather, you may need to wash your filter more frequently than the recommended period. For questions or concerns about the location or installation of the filter contact the HVAC manufacturer or a reputable HVAC contractor.
2. How long does my filter last?
The life of your filter depends on your environment and the type of filter you have installed. If there are a lot of airborne contaminants in your home because of a remodeling project, use of candles or incense, or increased activity levels, you will need to check your filter more frequently. If it is loaded with dust and dirt, it should be changed. Different types of filters have different life expectancies. Fiberglass filters last up to 30 days. Pleated filters last up to 90 days. Washable filters should be washed every 30 days and last up to 5 years. Mini-pleated filters should be vacuumed every 60 days and last up to one year. There is no standard for an "average home."
3. Why do pleated filters last longer than fiberglass filters?
Pleating the filter media allows more media contained within the filter frame. More media means more surface area to capture and hold particles. This capacity to hold more dust makes the pleated filters last longer than fiberglass filters.
4. What does MERV mean?
MERV is an acronym for Minimum Efficiency Reporting Value. This is now an international industry standard set up by the committee that oversees the filter industry. This standard is used for determining the filters ability to capture and hold dirt and dust in specific size ranges. Some filter manufacturers use their own rating system. Which is not approved as an industry standard. Always ask for the standard MERV number.
5. "Pressure Drop" and "Resistance", what should that mean to me?
The terms pressure drop and resistance are the same with respect to HVAC units and the elements, including filters, that comprise them. Airflow is a very important factor in an HVAC system. It helps in determining the efficiency of the unit and an excess amount can even spell problems that could result in expensive repairs or replacement of a system. The more pressure drop or resistance experienced by an HVAC system the less airflow that system has. The way a system is designed and installed as well as the filter used determines how much resistance to the airflow there is. This includes the type of duct work used, the amount and size of the room outlets and return air openings, the length and amount of turns in the system duct work, the filter size and other factors. It is important to try and keep the filter changed or washed as often as needed. As the filter gets dirty the resistance increases, thus increasing the total resistance of the HVAC system and lowering the amount of airflow. There is no easy way for a homeowner to tell how much resistance there is in the HVAC system.Check you filter often and if it is dirty, then it is time to change your filter or wash it.
6. What is the difference between nominal and actual filter sizes?
The nominal filter size is the approximate size up of the filter rounded up to the nearest "whole" inch. This makes the filter easier to identify for the consumer and allows for filters to comfortably fit into specified space in a residential furnace without air by-pass. The tolerances allowed for with this nominal size are +/- 1/8" for both the width and length. The actual size is just as it sounds; it is literally the exact dimensions of the filter. For example, the nominal size of a Dust Shield filter could be 20x20x1 however its actual size is 19 5/8"x19 5/8"x13/16". This may not be true for all manufacturers. Be sure to note the actual size required for you unit before purchasing and changing your filter.