The other night I discovered a puddle of water leaking from underneath the furnace while the air conditioner was running.
According to what I could find on the internet the three most common causes of this are a blocked drain line, a cracked drip pan or a clogged cooling coil.
I quickly determined the drain line wasn’t clogged so that meant a call to the air conditioning people. As I am a club member with a maintenance contract, they arrived that same day and the tech told me the same thing I saw on the internet. I always try to investigate problems in advance...I want to know if service people are blowing smoke!
It was determined the problem was the coils were clogged resulting in a lot of air not passing through them which in turn meant water was blowing all over inside; plus there was a loss of efficiency.
According to the technician the problem was probably caused by years of using those ubiquitous cheap green air filters. He said they let too much debris through and eventually the coils will clog.
Is that really true? Well, shortly after he left I was talking to my neighbor and guess what? Years ago he had the same problem and they began using Filtrete pleated filters, exactly the ones recommended by the service technician.
The choice of which furnace air filters to buy for your furnace depends many things. How much you want to spend, what you’re trying to filter, and how diligent you are about changing the filter are all considerations. As with many things in life, cheap isn't always the best bargain!
The minimum efficiency reporting value (MERV) scale goes from 1 to 16. Most residential filters range from 4 to 12. Maintaining the furnace manufacturer’s specified airflow is critical to achieving energy efficiency and maximum life from the blower motor and heat exchanger.
An inexpensive MERV 4 filter captures 80 percent of the particles 50 microns and larger, but only 25 percent of the particles in the 3 to 10 micron range.
For most homeowners, a more expensive MERV 7 or 8 pleated filter provides a good balance between cost and filtration efficiency. These filters trap 80 to 95 percent of the particles 5 microns and larger—more than enough filtration for most households.
But if you have family members with allergies or low-immunity issues, high-efficiency (MERV 11 and higher) filter are recommended, but one must make sure you stay on top of changing them. They will also, according to the technician, cut down on air flow and the efficiency of the air conditioner.
High-efficiency filters capture 99 percent of airborne particles such as bacteria and viruses, fumes and pollen. But you’ll have to run your furnace fan full time to get the maximum benefit. That will, along with the increased cost of the filters, cost more.
Never switch to a high-efficiency filter without first talking to a HVAC technician. They will have to boost fan speed to compensate for the reduced airflow. In our case increasing the fan speed isn't possible because of the location of the furnace. The increased fan speed also increases the noise level in the adjacent family room to the point that you couldn't hear an elephant break wind!
With these filters it is essential to be diligent about replacing the filter regularly. A clogged filter can burn out the blower motor, damage the heat exchanger and cost hundreds of dollars in wasted energy.
So...furnace filters DO matter!