It’s an unspoken rule that every two to three months, homeowners should change or wash their furnace filters to keep their indoor air quality clean and to maintain the efficiency of their furnaces. However, when your filters are barely getting dirty even after heavy reliance on your heating system, it can get confusing. On the one hand, you might think your house is super tidy and that there is no dirt, pet dander, or any other particles in your air. On the other hand, you could suspect a problem with the furnace. Here is what you should know.
The Role of Furnace Air Filters
The furnace filter’s job is to catch and trap all the particles present in the passing air. This includes dust, pet dander, mold spores, VOCs, smoke particles, and even smells.
Filters consist of fine fibers tightly strung together to block, capture, and hold particles until you manually remove them. Their effectiveness is rated using a metric known as Minimum Efficiency Reporting Value (MERV). The higher the MERV, the more closely knit the filter’s fibers are, and thus the more particles captured.
The Shocking Cleanliness of Your Filter
Low MERVE Rating
When your furnace filters have a MERVE rating lower than four, it means that the fine fibers are widely spaced. Most particles can pass through them with the moving air. If you live in an environment without much dust, your filters will stay clean for a much longer time. However, note that that doesn’t mean your air is clean.
Poor Filter Installation
Your furnace filter should snugly fit inside its holder so that no air can pass through the vents without going through it. If this is not the case, air can flow around the filter carrying most contaminants with it.
Your Furnace Isn’t Working
If your furnace isn’t strong enough to pick up dust and pet dander in your air, then your filters will remain clean. This often occurs when you have a malfunctioning blower motor, air pressure imbalance, or obstructed ductwork.
Blower motors go bad due to rust in the internal components, damaged fan blades, and issues with the bearings. Air pressure imbalance occurs when the flow of air from your room is disrupted by another opening, such as a door. This interference prevents air from returning to the vent where the filter is located.
Obstructed ductwork also disrupts the pressure balance inside your home. Remember, your furnace maintains a closed air loop inside your home to effectively condition the air. The amount sucked to be heated must be returned fully to fill up the vacuum it had left. When the duct is clogged, little to no air will be pushed out, meaning the filters will barely trap anything.
Home Environment
For your filters to trap particles in your indoor air, they must be suspended and carried by the air to your furnace. If the movement of people, pets, or even air itself (drafts from windows and doors) disturbs these particles so much that they can’t get to your furnace, the filters won’t trap them.
Similarly, dust and other particles tend to settle on surfaces if you have a sealed home without too many inhabitants and pets. They won’t be sucked up into the furnace for the filters to trap them. Also, if you vacuum every day and limit the mixing of outdoor and indoor air, your filter will likely remain clean for a long time.
The Negative Effects of a Clean Filter
Having clean filters is satisfying because it reduces your frequency of replacements or washes. However, this should also serve as a reminder to pay close attention to your indoor air quality and furnace.
A dirty filter means that harmful contaminants, microorganisms, and dust particles are not in your air or lungs and your furnace performance is as effective as it should be. Your chances of having allergic reactions, asthma attacks, headaches, and dizziness will be low, and all sections of your house will be warm and cozy.
Fixing a Clean Filter
1. Get the Right Filter for Your House
The first step to fixing a clean filter problem is getting the type for your furnace. A good filter should fit perfectly on the filter slot. Look at the owner’s manual recommendations before replacing them. You could also consult with an HVAC technician to assess the filter slot size and recommend the best size for your furnace.
Next, understand the type of pollutants you have in your home to get the best filter for the job. For example, if the filter you obtain is designed to trap dust and pet dander, it will remain clean if the pollutants in your home are microorganisms and very fine chemical residues.
An overall great choice to consider is a HEPA filter. They are densely packed with layers of fine mesh that can trap almost all pollutants available in a home, from dust to bacteria. Their MERV rating ranges from 17 to 20. However, be careful not to get one that’s too restrictive to decrease airflow.
2. Service Your Furnace
An efficient furnace will circulate all the air available in your room, with all its constituents, and condition it as needed. A dirty filter means that your furnace is efficient at its job.
Schedule furnace maintenance, especially during season transition, to prepare it for a new challenge. A tune-up involves inspecting the vent system and air intake grilles, lubricating all moving parts, inspecting the electrical connections and replacing damaged wiring as needed, cleaning the ductwork, and more.
3. Consider Investing in Ceiling Fans
A ceiling fan will assist your furnace in pulling air from every corner of your room and cleaning it via the filters. Even the heavy particles that tend to settle will be trapped and removed.
An added advantage of a ceiling fan is that you can use it to cool your home during the hot months instead of or alongside your AC. This can help reduce your utility bills, especially if you invest in an energy-efficient model.
4. Prevent Negative Air Pressure
Make your home less airtight to prevent problems with negative air pressure that could be making your furnace filters shockingly clean. Negative air pressure is a phenomenon that occurs when more air is drawn outside of your home than is coming in. In other words, more contaminants are escaping outside instead of being trapped by your filters.
The problem with negative air pressure is that it overworks your furnace. Ultimately, your furnace needs to maintain a closed air loop to effectively condition your home. When more indoor air escapes, the system must work harder to draw in additional air, leading to increased wear and tear.
You can prevent negative air pressure by properly insulating your home and ducts, sealing leaks and gaps, and minimizing the use of exhaust fans. Also, if you have heat recovery ventilators, consider hiring a professional to ensure the pressure is balanced.
Contact Matheson Heating, Air & Plumbing for More Information
If you live in Southeastern Michigan, call Matheson Heating, Air & Plumbing today for all your heating maintenance, furnace, and air filter needs. We can help you decide which filter is best for your home and fix any problems you might have with your furnace. We also offer other services such as tankless water heater installation, water filtration and softening, and drain repair.