Seasonal allergies in St. Louis? Your HVAC system might be making symptoms worse. Learn the signs and how to improve indoor air.
A poorly maintained or outdated HVAC system can circulate dust, pollen, pet dander, mold spores, and other airborne allergens throughout your home. In this post, we’ll walk through the key signs that your HVAC system is aggravating allergies, why it happens, and how you can take action to create a cleaner, healthier home environment.
Extremely thorough and educational. They do a wonderful job of explaining everything and making sure I was comfortable knowing how the systems worked in my house!
Response from the owner:Thanks for the great review, Matthew! We appreciate your support.
I noticed a strange noise that I was concerned was linked to my furnace. I called Thomas Hoffman Heating & Cooling and Nick came right out. He was very thorough checking all components. Thankfully all checked out for us this visit. Definitely recommend Thomas Hoffman Heating & Cooling!
Response from the owner:Thank you so much for the kind review, Abby! We appreciate your business and look forward to servicing you in the future.
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!
Got a quote over the phone. Everything was explained thoroughly. Dakota, my technician arrived and on time, was very professional and knowledgeable. He didn’t try to upsell or change anything. He did a great job. We can already tell the difference since the ducts and vents were cleaned. Would recommend an use Hoffman again in the future.
Response from the owner:Happy to hear you had a pleasant experience using Thomas Hoffmann!
The technician, Ryan, was knowledgeable and helpful in identifying the issue with our mini split AC unit. They are the second company we called after issues with the first and will be using Hoffmann again.
Response from the owner:We are so happy to hear your experience with Thomas Hoffmann was pleasant. Thank you for your kind review, & we look forward to working with you in the future!
woke up to a very cold house, called Thomas Hoffmann, they were able to come out a couple of hours later and get the issue resolved. Always trust them, they have always been quick to respond and get either the heating or ac issue fixed that day. Also a great price!!!! give them 10 stars if i could, Thank You JS
Response from the owner:Thank you for the kind review, Jim. We are happy to hear that you had a positive experience working with Thomas Hoffmann!
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 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!
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!
Ryan was knowledgeable and figured out why our furnace wasn’t working and repaired the problem
Response from the owner:So happy to hear you had a good experience with the team here at Thomas Hoffmann, Jo! Thank you for your support.
1. You’re Experiencing Allergy Symptoms Indoors — All Year Long
If you notice that allergy symptoms persist regardless of the season, your indoor air quality may be the culprit. Common indoor allergy symptoms include:
Sneezing
Runny or stuffy nose
Itchy eyes or throat
Skin irritation
Frequent headaches
Your HVAC system could recirculate airborne irritants like dust mites, mold, or dander. Without proper filtration and regular maintenance, allergens can thrive inside your home and your ductwork.
2. You Notice Excessive Dust Around Vents and Furniture
A telltale sign of a compromised HVAC system is a noticeable layer of dust, especially near air vents. If dust builds up quickly after cleaning, your system may not filter the air effectively. This can happen if:
Your HVAC filter is clogged or of too low quality (e.g., low MERV rating)
Your ductwork is dirty or leaking
Your air returns are pulling in unfiltered air from dusty areas like attics or crawl spaces
This dust isn’t just a nuisance — it’s a vehicle for allergens like pet dander and pollen to circulate through your home.
3. Your Air Filter Is Dirty (or You Can’t Remember the Last Time You Changed It)
Your HVAC filter is your home’s first line of defense against allergens. But if it’s clogged or outdated, it can no longer effectively trap particles. It can restrict airflow, forcing your system to work harder and potentially blowing allergens into your home.
We recommend St. Louis homeowners:
Change filters every 1–3 months
4. A Musty or Moldy Smell is Coming from the Vents
If your HVAC system smells musty, it could indicate mold growth inside the ductwork, air handler, or evaporator coils — all of which can significantly worsen respiratory symptoms.
Mold thrives in humid environments, which is common in St. Louis, especially in spring and summer. Your HVAC system may be contributing to this problem if:
The condensate drain line is clogged
There’s excess moisture in your ductwork
Your home lacks proper dehumidification
A professional inspection can help detect and remove mold sources before they become a health hazard.
5. You Hear Unusual Noises or Your System Runs Constantly
An overworked or aging HVAC system may struggle to regulate temperature and humidity, creating ideal conditions for allergens to flourish. If your system runs nonstop or makes banging, rattling, or squealing sounds, it may not distribute air evenly or filter it effectively.
This can result in stale, poorly ventilated indoor air that traps allergens instead of removing them.
6. Your Humidity Levels Are Out of Balance
Humidity plays a major role in indoor air quality:
Too much moisture (>60%) can fuel mold, mildew, and dust mites.
Too little humidity (<30%) can dry out mucous membranes and worsen allergic reactions.
In St. Louis, homes often swing between humid summers and dry winters. Your HVAC system should help regulate indoor humidity, but if it doesn’t, consider a whole-home humidifier or dehumidifier.
7. You Haven’t Had Your Ducts Cleaned in Years (or Ever)
Over time, your ductwork can become a hidden hotspot for dust, mold, pollen, and even insect debris. Your system can blow those allergens back into your living spaces every time it runs.
If it’s been years (or decades) since your ducts were cleaned, you may benefit from a professional duct cleaning, especially if:
You have pets
You’ve recently renovated
You’ve moved into an older home
How to Allergy-Proof Your HVAC System
The good news? You don’t have to live with allergy-aggravating air. Here are simple yet powerful steps you can take:
Upgrade your air filter to at least MERV 11.
Schedule seasonal HVAC maintenance (spring and fall are ideal).
Install a whole-home air purifier or UV air scrubber.
Seal and clean your ductwork to eliminate hidden allergen sources.
Balance your humidity levels with a humidifier or dehumidifier.
Keep your home well-ventilated, especially bathrooms and kitchens.
Trust the Local Indoor Air Quality Experts in St. Louis
At Thomas Hoffmann Air Conditioning & Heating, we’ve helped hundreds of St. Louis families improve their home’s air quality and reduce allergy triggers, boosting energy efficiency and comfort. Whether you need a filter upgrade, duct cleaning, or a full IAQ solution, our licensed technicians are here to help.
Breathe Easier. Live Better.
Contact us today to schedule a free indoor air quality consultation. With local expertise you can trust, we can create a healthier, allergen-free home together.
1 thought on “Signs Your HVAC System Is Aggravating Allergies”