When you go to a hardware or big box store to purchase air filters you will find a bewildering array of products. 3M, for example, offers 9 different types of filters each with different ratings and at a different price, and then each of those comes in different sizes. It can be confusing, to say the least! We’ll help you make sense of it all, so you can choose the best air filter for your needs.

Size Matters

Size is perhaps the easiest decision: get the size filter that fits the filter holder built into your HVAC system. It should fit snugly, with no air gaps around the filter. Be aware that filters come in thicknesses of 1-inch to 6- inches, with the thicker filters having greater capacity to catch dirt without increasing resistance to air flow and increasing the time between required filter changes.  However, you cannot put a thick filter (4 or 6 inches thick) into your HVAC system if it’s designed to accommodate only a 1-inch thick filter.

Rating Matters

In our previous post, we talked about the MERV ratings of filters.  MERV is an industry standard measurement of filter efficiency.  Individual manufacturers often have their own rating system as well.  3M’s rating is called MPR, which standard for Microparticle Performance Rating.  As with the MERV rating, higher MPR numbers mean a greater percentage of particles and smaller particle sizes will be captured by the filter.

Price vs Performance

How do you decide which MERV rating to get?  Generally, the higher the MERV (or MPR) rating, the more expensive the filter.  For example, the price of a MERV 13 filter is about twice the price of a MERV 8 filter of the same size. 3M offers multiple filters having a MERV 12 rating, but with different MPR ratings, and so even among filters of the same size and MERV rating, the prices can vary.  Which filter to buy depends on how much cleaning you want your filter to do. The lowest price filters at MERV 5 will remove dust, debris and lint. This is the minimum needed to maintain the health of your HVAC system’s heat exchanger and coils.  A MERV 11 filter removes smaller particles such as pollen, dust mites, mold spores, and pet dander. A MERV 12 or 13 filter can filter some bacteria, viruses, and odors.  Since the prices jump up dramatically at MERV ratings higher than 11, and the increased efficiency is only minimally incremental, using filters with more than a MERV 11 rating is probably not cost effective, unless there is some particular medical need.  In the chart, those shown in the “green zone” in the cost column represent the best value on a price vs. performance scale.

You’ve heard us preach over and over about how important it is to change your air filters on a regular basis. But there are so many to choose from these days and prices vary widely!  We’ll help you make sense of it all in this and two subsequent posts on this subject.

What’s the purpose?

The purpose of an air filter is to keep the coils and heat exchanger inside your HVAC system clean. Dirty coils and heat exchangers can make the system work harder and cause it to be replaced earlier, so keeping the filter clean helps prolong the life of your HVAC system. Since the air in your house circulates past these filters, they also affect the quality of the air you breathe. People with allergies or asthma are especially sensitive to airborne particles like pet dander, pollen, mold and dust, and the right filter will filter out these particles.

What is a MERV rating?

When it comes to air filters, the most important thing to look for – besides the correct size for your particular system – is the MERV rating. MERV stands for Minimum Efficiency Reporting Value. It is a measurement standard designed in 1987 by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to rate the effectiveness of air filters. The MERV rating is a number from 0 to 20, with most residential air filters in the 4-12 range. The higher the MERV rating, the more efficient the filter is, and the greater percentage of particles it can capture. MERV is an industry standard rating, so it can be used to compare filters made by different companies.

As a general rule, prices are higher for filters with higher MERV ratings. Often HEPA filters are rated in the range of MERV 17 to 20, and are the most expensive types of filters. But here is one instance when the most expensive may not be the best!  Most residential HVAC systems may not have enough fan or motor capacity to accommodate higher efficiency filters, such as those greater than MERV 16. Always check your HVAC manufacturer’s recommendations.

Installation Affects Performance

How a filter is installed also effects its performance. If a filter is installed such that air bypasses the filter, its effectiveness will go down substantially, so make sure the filter is the right size and it’s a snug fit. Plus, most filters are directional, meaning you have to install them facing the right direction. Check for the arrow which indicates the direction of air flow, and install the filter with the arrow pointing towards the duct. Here’s another tip: If you have your HVAC system’s fan set to “auto” then the air is only going past the filter when your system kicks on. By setting it to “on” the fan will continually move air across the filter, so the air you breathe will be continually filtered.

Most Important Thing

The most important thing to remember about home air filters is to change them regularly. Even the highest-quality filter won’t work if it is clogged with particles!  Check the filter manufacturer’s guidelines, as different filters are meant to be changed at different intervals. Plus, if you’re doing remodeling, there is construction going on, or you have pets, you will need to change your filters more frequently to compensate for the extra dust and residue in the air. Mark the date of installation along the filter’s frame, so you can clearly see when it was last changed.

Nashville is known for its great music, hot chicken, and unfortunately, its sometimes poor air quality – largely due to ozone, pollens and particulates. Things linger in our air because middle TN sits in a “bowl” surrounded by mountain ridges and vegetation the natural wonders that give this area its beauty. People who are allergy-sensitive know all too well that springtime is approaching!  Of course, you should be changing your air filters on a regular basis at least every 3 months. But, did you know there is more you can do to help the air quality in your home?  Consider installing a whole-house electronic air cleaner.

What is an Electronic Air Cleaner?

This is a device that attaches directly into the HVAC ductwork feeding your whole house. As the name implies, this is an electronic filter not just some folded mesh encased in a cardboard frame like a typical air filter. It works by placing a negative electric charge on airborne particles and a positive electric charge on the media and, because opposites attract, it collects airborne particles like a magnet. To give you some perspective, typical air filters remove particles down to about 750-1000 microns in size, or about the size of the eye of a sewing needle. But, an electronic air cleaner can remove particles less than 10 microns in size a size so small it would require an electron microscope to see!  Particles of this small size stay suspended in air easily and account for 99% of the total number of particles in unfiltered air.

Low Maintenance

Besides dramatically increasing your air quality, electronic air cleaners are low maintenance and economical. They can be easily removed from the ductwork, washed in your dishwasher or sink, drip dried, and re-installed. They do not have to be replaced every 3 months like typical air filters. Some systems offer an integrated LCD display or fault light to remind you when the filter needs cleaning. Runtime on these filters is not based on calendar days, but on the length of time your HVAC system runs. It is recommended that you leave your HVAC system’s fan set to “on” rather than “auto” for maximum air cleaning benefit. Most electronic air cleaners come with a 10-year warranty and use about as much electricity as a 40-watt light bulb.

Electronic Air Cleaner Vs. Electrostatic Filter

Do not confuse electronic air cleaners with electrostatic air filters! Electrostatic filters have a charge applied to them at the factory which is supposed to last the life of the filter, but their efficiency is poor at best and degrades over time. Electronic air filters are made using either precipitator or polarized media technologies, both of which require a power supply. Electronic air cleaners have a continuous charge applied making them very efficient dust magnets!

Other Benefits

In a previous post, we talked about duct cleaning. But, if you have an electronic air filter and well-sealed ducts, you should never need your ducts cleaned, as particles won’t ever get the chance to deposit themselves in the ducts or build up over time. Additionally, your HVAC system’s blower, air conditioning coils, and heat exchanger will be protected from particles and so will last longer and be more efficient. In fact, one electronic air cleaner manufacturer guarantees that if your indoor coil requires cleaning within 10 years of  installing their electronic air cleaner, they will pay to have it cleaned!

Don’t Forget This

Whether you have a whole-house electronic air filter or not, you still need to change your air filters in your return air vents every three months!

It always seems your heat will go out on the coldest day of the year!  Why spend money when you may be able to fix it yourself? Here are a few examples of do-it-yourself easy fixes:

Thermostat

Is the display on your thermostat blank? It could be because it needs a battery, or that the circuit breaker to it has been tripped or you’ve blown a fuse. Reset the tripped circuit breaker, replace the fuse, or replace the battery.  Other thermostat tips:

• Make sure all the wires going to the thermostat are connected and not loose.
• Check that the thermostat is in heat mode. This switch can easily get accidentally bumped while dusting.
• For programmable thermostats, check that it is set to the correct day and time, including the AM or PM designation.  One customer bought a programmable thermostat to save money, with the intent to have the heat backed down while the customer was away at work, and have the heat cranked up at night when the customer was home.  When the customer started freezing at night, they mistakenly thought something was wrong with the heat, when the real culprit was they had the AM/PM designation backwards on their thermostat!
• If you had a recent power outage, it could be that all of the settings on your programmable thermostat have been wiped out.  Often there is a battery backup in these units, so you may need to change the battery and then re-enter your settings.

Furnace

If the heat is out and you do not even hear the fan coming on (no air coming out of the supply registers), there may be no power to the furnace.  This is often due to someone flipping the switch accidentally while cleaning out the attic or basement (areas where the furnace may reside). The switch often looks similar to a light switch and easy to mistakenly turn off.  Just flip the switch back, and you should hear the furnace start up within 3-5 minutes. Other furnace tips:

• Many thermostats get their power from the same electrical circuit that feeds the furnace system, so if your thermostat is blank, turning on the switch by the furnace may be the solution.
• If the fan runs, but the air coming out is cold, you have a problem with the furnace (or heat pump) itself, and may need a service call.
• Some furnaces have emergency cut-off switches that are activated when a door or service panel is removed. If the furnace door is not closed properly (such as after a filter cleaning), or has been accidentally bumped open, the cut-off switch will prevent the furnace from coming on.  Verify all access doors are properly closed.

Electrical

If the switch is on to the furnace and it still doesn’t come on, it could be that the circuit breaker or fuse to the furnace (or heat pump) is tripped or blown.  Reset the breaker by turning it all the way OFF, then back ON. If the fuse for the furnace is blown, replace it with the same size and type of fuse.  Important electrical tip:

• If a breaker keeps tripping or a fuse keeps blowing, contact a qualified electrician to inspect your system to determine why you are having problems.

Filters

A dirty air filter restricts air flow, and the system will work harder and build up pressure. Newer, more efficient furnaces are sensitive to this pressure build up and turn off before the dirty filter can cause further damage. At the very least, a dirty, clogged filter will reduce the heat output of your system. The simple solution is change the filter!   Important tip:

• Don’t try to just vacuum the existing filter and re-insert it. The material inside the filter will still be saturated. Just place the old filter in the trash and insert a new one each time… at least every 3 months.

If none of these DIY fixes addresses your problem, give us a call.  We’re always here to help!

Fall and spring are great times to do small maintenance jobs around the house, before the extreme cold or hot weather sets in.  It is a good idea to make cleaning the vents and ducts part of your yearly spring and fall cleaning routine. After watching the video try out this fun Test your knowledge.

Follow these easy steps:

1. Turn your HVAC system to the off position by flipping the switch on your thermostat, or turn it down to where the system is no longer running. You do not want the system blowing air (in or out) while you are cleaning it!
2. Remove the vent cover or open the grill’s latch to expose the duct.
3. Do a visual inspection of the duct in case there is something that can be retrieved such as an earring, a coin, a pet toy, or other small object which has fallen in. Floor registers are particularly susceptible to things falling in.  Registers on the wall or in the ceiling are probably more susceptible to cobwebs.
4. Using your vacuum cleaner nozzle, a handheld vacuum, or a cloth, remove spider webs or any debris that may have fallen into the duct. Be careful not to damage the ductwork while cleaning it.
5. Clean and replace the register cover.  Then close the grill cover back over the duct.
6. Turn your HVAC system back on by flipping the appropriate switch on your thermostat.

Do this type of maintenance twice per year, as part of your spring and fall cleaning routine. In high-traffic and very dusty environments, or if you’re plagued by lots of pet hair, you may need to do this type of maintenance each time you change your air filters, which for most folks is about every 3 months.

Fall and spring are great times to get an HVAC tune-up, too, to make sure you’re ready for the upcoming heating or cooling season. And don’t forget to change those air filters!