Air filtration is an important part of your home’s ventilation system. Without an air filter in place, dust and other airborne particles would be distributed throughout your ductwork. This could aggravate allergies, build up on your vents to reduce airflow and possibly even create bigger problems over time.

This doesn’t mean that you can just grab any air filter and slap it in place, of course. Choosing the right air filter for your home is important if you want to get the most life out of your heating and cooling system. Stop for a moment and think about your HVAC system; do you really know what sort of air filter you need to keep things running in top condition? If you don’t, here’s what you need to know.

Where Is My Air Filter?

The first thing that you need to know about your air filter is exactly where in your house it’s located. This may seem kind of obvious, but some air filters are difficult to find. While the most common air filter location is behind a grate on one of the walls, some of these grates are in odd locations or are designed to somewhat blend in with the look of the surrounding wall. Filters may also be placed in the air handler unit (AHU) or rooftop unit (RTU). Buildings with split ventilation systems may even have multiple intakes that each have their own air filter. Depending on how your system is designed, it may take a bit of hunting to locate your filter.

Choosing an Air Filter

Once you’ve located your filter, it’s important that you choose the right one for your needs. Part of this involves finding the right size filter; different HVAC units are designed for different filters, and if you get one that doesn’t fit then you’re going to have trouble getting it (or keeping it) in place. Measure the dimensions of the area where the filter is mounted or look at the old filter and find the dimensions listed on it. Choosing an air filter is about more than just finding the right size, however; one other big consideration is the MERV rating (which stands for Minimum Efficiency Reporting Value.)
 

The MERV is a number that tells how good of a filter you’re buying. A low MERV of around 6 provides you with 35 to 50 percent efficiency at capturing large particles like dust, mold and pet dander. A MERV of 8 increases this to over 70 percent efficiency, capturing those particles as well as slightly smaller particles like pollen and dust mites. A MERV of 11 captures large particles with a greater than 85 percent efficiency, as well as medium particles like those found in auto exhaust with 65 to 80 percent efficiency. You can even go higher than that, with a MERV of 13 capturing large and medium particles with over 90 percent efficiency and small particles like smoke, bacteria and even odors with up to 75 percent efficiency.
 

There are other options available as well, such as HEPA filters (which you might hear referred to as high-efficiency particulate arrestance filters or high-efficiency particular air filters) that have an even higher standard of particle removal. HEPA filters must remove either 99.95 percent (in Europe) or 99.97 percent (in the United States) of all particles of size “small” or larger. Depending on the filter, this translates to a MERV value of around 17 to 20.

Air Filter Maintenance

There’s more to keeping your system running well than just installing a filter, of course. Most air filters should be changed monthly, though some may have different recommended use periods that should be listed on the packaging. Periodic cleaning of grates and vents may also be required to keep the filters clean and the system running efficiently. Failing to change your filters can reduce airflow and system efficiency, and over time, it can even reduce the life of your unit.

Spring is a time of beginnings. You get a chance to start over, to try something new and to get your air conditioner ready for the hot summer to come. It might not be as romantic as the budding of trees and blooming of flowers, but having your air conditioner in tip-top shape is arguably far more useful.

When you start your spring clean, don’t forget your air conditioner. In just a few minutes, you can improve its efficiency while helping it continue to run well for years to come.

First, A Basic Explanation of Air Conditioning Technology

Your air conditioner isn’t magic, but it’s pretty close. These devices were actually invented in the early 1900s as a way to reduce indoor humidity in paper plants. It just so happened they have a side effect that we rely on even today.
 

Air conditioning systems depend on the expansion and contraction of gasses to pull moisture out of the air by cooling it down. This is basic physics at work — warm air holds more water, cool air holds less.

When air is pulled into your air handler (for many, this is a furnace) through your warm air return, it’s forced over a tent-shaped coil that uses refrigerant to cool the air as it passes. A blower then blows that cooled air back into the house.

So What Does the Outside Condenser Do?

The air conditioning condenser that most people consider to be “the air conditioner” is actually a giant heatsink. See, when the air is cooled inside your air handler, the refrigerant is what’s absorbing most of the heat. It then gets pumped to the condenser, where the heat collected inside your house is released to the environment.

It’s really a pretty simple idea that has made a huge change to how we live, play and work.

Your Air Conditioner Spring Cleaning Checklist

There’s no time like spring to do a little air conditioner tune-up. A lot of the heavy lifting will have to be performed by HVAC professionals, but there are things you can do to keep your system running longer as a homeowner. Generally, these items should be done at least once in the spring before you start using the A/C and again in the fall when you’re ready to put it away for the year.

• Change your furnace filter. Whether it’s on the ceiling, on the floor or inside your furnace or air handler, a clean filter is a filter that can let the most air through for cooling. And the easier it is for the system to pull air in and cool it, the more comfortable you’ll be with the least amount of cost. Investing in an electrostatic filter that you can wash and reuse is a smart move for the long term.
• Flush your condensation line. There’s a pipe or tube that comes out of your furnace or air handler and runs to a drain somewhere. This is the condensation line. All the moisture your system is pulling out of that warm air has to go somewhere, you know? That somewhere is a pan that empties via this tube. Just open it up from the top (which tube it is should be obvious, but if you can’t find it, ask your HVAC professional), slowly pour in about a cup of vinegar or bleach. If the liquid moves, you’re gold. If not, you may need to spend some time investigating the issue. More often than not, it’s algae growth in the tube or mineral deposits, both things you can flush out, but require some patience to remove.
• Clean your a-coil. That tent shaped coil mentioned above is called the “evaporator coil” or the “a-coil.” It can get dirty, which makes it a lot less efficient at removing moisture and cooling the air. If you feel brave, and you’re careful, you can wipe the coils clean or use a shop vac. They’re very similar to the coils on the back of your refrigerator, treat them the exact same way.
• Comb the fins on the condenser. If you look closely at your outside condenser, you’ll notice that the part that’s inside the cage is made up of a whole bunch of teeny fins. These little guys can get damaged by accident, causing them to be less efficient because they’re not really in an optimal configuration anymore. All you need to fix this is a fin comb. This simple device lets you straighten bent fins, restoring your unit to its former glory.
• Spray the condenser down. Last, but far from least, you’ll want to spray your air conditioner’s condenser down with a hose. Start by wetting all the fins with a garden sprayer, then go back around and spend some time slowly flushing out the dirt, one section at a time, working top to bottom.