Tired of having to frequently change your AC filter? Here are five common reasons why your air filter gets dirty quickly, along with tips to minimize it.
Suppose you find yourself replacing your AC filter far more often than expected. In that case, you’re not alone — especially here in the St. Louis area, where changing seasons, humidity, and older homes can all contribute to dirty air filters. But while a dusty filter might seem like a minor nuisance, it can actually signal more serious HVAC issues and affect your indoor air quality, energy bills, and even your health.
The technician Giovanni was excellent and on time very professional and efficient and knowledgeable of the project at hand ,gave great advice but most of all did great work 👏 thank you .
Response from the owner:We are so happy to hear you had a great experience, Sam! Thank you for the review, and thank you for your business.
Your service technician was very professional and knowledgeable. And did not appear to try to give me bogus information. I truly appreciate his honesty because several other companies did not appear to be honest, obviously wasn’t honest, my gut feeling told me they were not honest and tried to get me to spend $10,000 for a problem that was much simpler to fix. I look forward to you servicing all my properties, and possibly those of the rest of my family.
Response from the owner:Thank you so much for the kind words and great review! We appreciate your support.
Very prompt, communication was great, and the workers were very polite. I highly recommend them!
Response from the owner:Thank you, Lianne! We're glad to hear that you had a positive experience with our team and appreciate your high recommendation.
Water heater repaired, appointment done the same day, effective, courteous
Response from the owner:Thank you, Leticia! We appreciate your kind words and are glad to hear that the water heater was repaired promptly and effectively. Your satisfaction means a lot to us!
Response from the owner:Thank you, Hank, for your wonderful feedback; we're glad you enjoyed the fast, friendly, and professional service, and we'll be sure to keep up the great work!
The service tech Giovanni did a fantastic job. Our gas fireplace is working like new again so we’re ready for the cold weather!
Response from the owner:Thank you, Mr, for your fantastic review! We're glad to hear Giovanni provided you with excellent service and professionalism. Your recommendation means a lot to us!
⭐️⭐️⭐️⭐️⭐️ If I could give 10 stars, I absolutely would.
Last night our furnace went out unexpectedly, and with three kids in the house, the temperature dropped fast. Giovanni went above and beyond in every way possible. Instead of charging me a late-night service fee, he simply asked, “Are you decently handy?” and offered to walk me through some troubleshooting steps to get our heat back on so my children wouldn’t have to sleep in the cold.
Not only did he guide me through the process, he even FaceTimed me and showed me exactly what to take apart, how to put it back together, and what signals to watch for. It felt like having a real technician standing right next to me the entire time. Thanks to him, our heat was restored within minutes.
In a world where true customer service is hard to come by, Giovanni is a rare find. It is a guaranteed fact that any future repairs, maintenance, and the new heater/AC system we’ll be needing this coming summer/fall will absolutely be done through him. His honesty, kindness, and expertise have earned our business for life.
Highly, highly recommend.
Response from the owner:Thank you, Jeff, for sharing your experience! We're so glad to hear Giovanni was able to help you and your family during that tough situation. Your recommendation means a lot to us, and we appreciate your trust in our services for the future!
My neighbor referred these guys to me when had water heater problem. Previous company told me I needed to replace it. Tom’s technician fixed it for less than $200. This was over 2 years ago and have been using their service ever since. They are very trustworthy.
Response from the owner:Thank you, Mary, for sharing your experience and for trusting us with your water heater issue; we're glad our technician could help and that you've continued to rely on our services!
I called this company earlier today because I was having a bunch of issues with my HVAC system. They were incredibly friendly and walked me through troubleshooting step by step over the phone. They didn’t even charge me for the call. Thanks to their honest advice, I was able to get things running smoothly again. Really grateful for their help and would definitely recommend them if you want straightforward and trustworthy service. Five stars all the way!
Response from the owner:Thank you so much for the glowing review, Hector! We appreciate your business and look forward to working with you in the future.
Nick did not set current time. — Monday Hoffmans Zach came to fix correct time. We DID NOT want a timed thermostat — we prefer to set temperatures manually
Response from the owner:Thank you, Pat, for your kind words about Giovanni; we appreciate your feedback and are glad to hear that he made a positive impression.
Clear communication about arrival, service and costs.
Response from the owner:Thank you, Margaret, for your kind words! We appreciate your feedback on our clear communication and are glad you had a positive experience.
I will highly recommend this business for your air and heater repair. Prompt, knowledgeable and courteous service.
Response from the owner:Thank you, Judy, for your kind words and recommendation! We're glad to hear you were pleased with our prompt and courteous service.
Thomas Hoffman was very responsive to our after hours inquiry, even walked us through some trouble shooting over the phone. We provided pictures of the unit and they were able to quickly buy, schedule and install the part to keep our family warm!
Response from the owner:Thank you, Ali! We're glad to hear that Thomas was responsive and helpful in getting everything sorted out for you and your family. Your feedback means a lot to us!
Nick came by, identified the problem quickly and had it fixed. Great service!
Response from the owner:Thank you, Ted! We're glad to hear that Nick provided you with quick and effective service. Your feedback is greatly appreciated!
Great service. Responsive. Well trained technicians. Honest friendly and thorough. I highly recommend Tom Hoffmann and his team.
Response from the owner:Thank you for your kind words! We appreciate your recommendation and are delighted to hear about your positive experience with our team.
Ryan Taylor with Thomas Hoffman did an outstanding job in servicing our unit & explaining everything to me, especially how our humidifier worked, since we were new home owners & had not had one before. Thank you!
Response from the owner:Thank you! We're glad to hear that Ryan and Thomas provided you with excellent service and helped you understand your new humidifier. We appreciate your feedback!
As always, the Hoffmann technician Zach was polite, professional, and efficient. Pricing is reasonable and even more importantly, they are dependable. I will continue to use Thomas Hoffman A/C and Heating.
Response from the owner:Thank you, Mark, for your kind words about our technician and for your continued trust in Thomas Hoffman A/C and Heating; we truly appreciate your support!
Response from the owner:Thank you, Brandon! We appreciate your kind words and are glad to hear about your positive experience with Hoffmann’s professionalism and thoroughness.
Our service technician arrived right on time and was professional, friendly, efficient and courteous. We couldn’t ask for more.
Response from the owner:Thank you for sharing your positive experience with our service technician! We appreciate your kind words and are glad to hear that you were satisfied with the service provided.
I'm a new customer and had my first appointment for furnace check.My tech was Zack and what a professional. He explained how he checked system and answered all my questions. This was a very good experience
Response from the owner:Thank you, Patricia, for your kind words! We're glad to hear that Zack provided you with a professional and informative experience during your furnace check. Your satisfaction means a lot to us!
Thomas Hoffman is a wonderful company to work with. Techs are knowledgeable, personable & efficient.
Response from the owner:Thank you, Christine, for your kind words about our team; we appreciate your feedback and are glad to hear you had a positive experience!
I called on December 25th at midnight and started leaving a message and Thomas Hoffman the owner called me back almost immediately. He said he would come out the next morning between 8:00 and 10:00 am snd he was promptly on time. He fixed my problem and while he was there I decided to get an estimate for a new furnace and air conditioning unit. The price was very reasonable and the installers one of them being his son were both very professional very courteous, polite, arrived on time and finished the same day. I enjoy knowing that I now have the support of Thomas Hoffman heating and air conditioning along with the peace of mind that comes with owning a Trane. Nothing stops a Trane.
Albert Koesterer
Response from the owner:Albert thanks so much for your kind reviews and your business. We truly appreciate it!!!
The Thomas Hoffmann team did a great job taking care of our semi annual HVAC maintenance. They not only worked with us to schedule the visit, but also did an excellent job sending us reminders on when they would be out.
Response from the owner:Thank you so much for the great review, Bob! We appreciate your support and are happy to hear you had a great experience!
1. Poor Indoor Air Quality (Dust, Pet Hair, Pollen & More)
St. Louis homes — especially older ones or those near major roadways — tend to collect more airborne particles than you might expect. If you have:
Pets that shed
Carpeting or rugs that trap dust
Open windows during allergy season
Smokers in the home
…then your HVAC filter is working overtime to trap it all.
What You Can Do:
Vacuum and dust frequently.
Bathe pets regularly and brush them outdoors.
Use a high-efficiency vacuum with a HEPA filter.
Consider an in-duct air purifier or whole-home filtration system to reduce particle load.
2. Running the AC Constantly in St. Louis Summers
Let’s face it — St. Louis summers can be brutally hot and humid. That means your AC is likely running longer cycles (or continuously) during peak months. The longer it runs, the more air it pulls through the system — and the faster your filter fills up.
What You Can Do:
Use ceiling fans to distribute cool air and reduce AC load.
Keep blinds closed during peak sun hours to reduce indoor heat gain.
Make sure your thermostat is set efficiently (72–75°F is usually comfortable).
Schedule seasonal maintenance to ensure your system isn’t overworking.
3. You’re Using the Wrong Filter (Or a Cheap One)
Not all air filters are created equal. Some homeowners use cheap fiberglass filters that clog quickly and do a poor job of protecting their system. Others use high-MERV filters that trap more — but also block airflow and require frequent changes.
What You Can Do:
Avoid using a high-MERV filter unless your system is designed for it.
Consider a media filter cabinet that allows for high-capacity filters to be changed every 6–12 months.
Need help selecting the right filter? Our techs at Thomas Hoffmann Heating & Cooling can match your HVAC system with the best filter for performance and air quality.
4. Duct Leaks Are Sucking in Dust & Debris
Leaky ducts — especially in unfinished basements, attics, or crawl spaces — can pull in unfiltered air filled with dust, insulation particles, and other contaminants. This not only dirties your filter faster, but it also reduces your system’s efficiency and can raise your energy bill by up to 30%.
What You Can Do:
Have your ductwork inspected for leaks, holes, or disconnections.
Consider professional duct sealing to prevent air infiltration.
Insulate and seal return air ducts to keep the system clean and efficient.
5. High Humidity Levels in the Home
Humidity is no stranger to St. Louis. When indoor air is overly humid, it can encourage mold growth and dust mite activity — both of which contribute to dirty filters. Mold spores, in particular, can build up quickly and may even spread to your HVAC system if left unchecked.
What You Can Do:
Use a whole-home dehumidifier to control moisture.
Keep indoor humidity between 35% and 50%.
Run bathroom and kitchen exhaust fans when showering or cooking.
Inspect for leaks around windows, doors, or in the basement.
🚨 How Often Should You Change Your AC Filter in St. Louis?
Here’s a quick rule of thumb based on household conditions:
Home Type
Recommended Filter Change
No pets or allergies
Every 90 days
One pet
Every 60 days
Multiple pets/allergies
Every 30–45 days
High-efficiency filters
Every 6–12 months (check specs)
Still unsure? If your filter looks gray, clogged, or discolored, it’s time to replace it.
🧰 Schedule a Clean Air Assessment with Thomas Hoffmann Heating & Cooling
If you’re tired of changing filters constantly or worried that something more serious might be going on, we’re here to help. Our team at Thomas Hoffmann Air Conditioning & Heating provides expert HVAC inspections, filter recommendations, duct cleaning, and air quality solutions for St. Louis-area homes.
At Thomas Hoffmann Air Conditioning & Heating, we pride ourselves on being a locally owned and operated HVAC company. With more than 30 years of experience and a master technician and mechanical engineer as our owner, we can replace, repair, and maintain your business or home’s HVAC system.
