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A poorly maintained or outdated HVAC system can circulate dust, pollen, pet dander, mold spores, and other airborne allergens throughout your home.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.
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!
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!
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.
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.
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!
Nick was excellent. Super profession, quick, and up front with the pricing (which was fair). Hopefully we don't need to call anyone to fix our AC again, but if we do - I'm calling Nick!
Response from the owner:Thank you, Layton, for your amazing review! We really appreciate your support and hope to be your first call for any future repairs!
Same day service. Technician arrived as scheduled. Replaced capacitor quickly. Friendly technician. Repair cost $429 seemed high for inexpensive part and 20 minutes labor.
Response from the owner:Thank you, Tom, for your feedback! We're glad to hear the technician was prompt and friendly, though we understand your concerns about the repair cost. We appreciate your insights and hope to serve you again in the future.
Response from the owner:Thank you so much, Al, for your excellent review; we truly appreciate your support and are glad to hear you had a great experience!
Thomas Hoffmann is the most professional and courteous of all the HVAC companies in St. Louis. It has kept my HVAC systems in good working order through the hottest and coldest days for many years.
Response from the owner:Thank you, Jonathan, for your kind words about our professionalism and courtesy; we truly appreciate your support!
I notified two companies at the same time regarding a malfunctioning AC unit and Wow! Super fast response from Hoffmann on a weekend no less, to fix our AC unit. Hoffmann’s tech responded to my call immediately and fixed our AC before Galmiche has even responded. Used to be a Galmiche customer, but will use Thomas Hoffmann from here on out!
Response from the owner:Thank you, Darlene, for your fantastic feedback! We're glad to hear that our team was able to respond quickly and resolve your AC issue. We appreciate your trust in us moving forward!
Ryan did a great job with my AC reinstall. Very knowledgeable company with Tom Hoffmann providing the engineering expertise.
Response from the owner:Thank you, Steve! We're glad to hear that Ryan did a great job on your AC reinstall, and we appreciate the shoutout to Tom's expertise. Your satisfaction means a lot to us!
These guy's are amazing same day service very well priced for the knowledge they have ask before doing anything to confirm they're my new go to
Response from the owner:Thank you, Cory! We're glad you found our service amazing and appreciate your kind words about our pricing and knowledge. We're here for you anytime!
My ac compressor was replaced. They always do a good job and they are always available when you need them.I think the price was a little too high since they only had to change the compressor in my unit. The compressor was under the warranty. Other than that Im very satisfied with the job the technician did.
Response from the owner:Thank you, Carlos, for your feedback and for recognizing the hard work of our technician; we appreciate your satisfaction with the job done and will take your pricing comments into consideration.
I was very pleased with your service. Prompt response would was most appreciated. The technician was very knowledgeable and prepared for the work. Also he was very personable and professional.
Response from the owner:Thank you, Richard, for your kind words; we appreciate your recognition of our technician's knowledge and professionalism, and we're glad you had a positive experience with our service.
Thank goodness for them coming out so quickly. Got our whole job done and we are COOL again. Thanks so much!!!
Response from the owner:Thank you, Sandy! We're so glad to hear everything got done quickly and you’re feeling cool again. We appreciate your kind words!
Had an amazing experience with Thomas Hoffman. They were very professional and solved the problem quickly. I would highly recommend!
Response from the owner:Thank you, Alex, for your wonderful feedback! We're glad to hear that Thomas was able to assist you so effectively. Your recommendation means a lot to us!
Zac did our service today. A very professional and courteous young man. He did a thorough inspection and cleaning on our HVAC system.
Response from the owner:Thank you, Tom, for your kind words about Zac's professionalism and thoroughness during your HVAC service; we appreciate your feedback!
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.
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