Understand BTUs and why they affect your HVAC system’s efficiency and comfort. Contact us today for expert sizing advice!
Whether upgrading your air conditioner, replacing your furnace, or installing a brand-new HVAC system, you’ve likely come across the term BTU. But what exactly does it mean — and why should homeowners in the St. Louis metro area care?
Responsive! Came over, even after hours to help resolve a critical issue that was caused by a lightning strike causing a gas leak. Would highly recommend!!
Response from the owner:Thank you for your kind words! We're glad our team was able to assist you promptly, especially during such a critical situation. Your recommendation means a lot to us!
Having Tom come to our aid was a great experience and he offered followup assistance with the fancy technology part of the appliance if we need it. We will call him again if the need arises. Merry Christmas.
Response from the owner:Thank you, Marilyn! We're glad to hear that Nick was able to assist you and provide follow-up support. We appreciate your trust in us and wish you a Merry Christmas!
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.
As always, the Hoffmann technician 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!
These guys are pros. Techs are friendly, listen and explain what they are doing. Office staff is responsive. Fast service....
Response from the owner:Thank you, Clark, for your kind words! We're glad to hear our techs and office staff made your experience a great one. Your feedback means a lot to us!
Excellent service. A/C went out on a weekend. Called them on Saturday morning, they were out within about 2 hours. The fix was easy enough, and he even had the part in the truck! I recommend this company for all of your HVAC needs
Response from the owner:Thank you, Elaine! We're glad to hear you received prompt service and that the fix was smooth. Your recommendation means a lot to us!
The service technicians are very courteous and communicate well with the customer. They let you know what, if any, problems are found, the options, and the cost of the repair(s). Quick and efficient.
Response from the owner:Thank you for recognizing our service technicians' courteous and effective communication, we appreciate your feedback!
These guys were great. Quick to return my call. Up front pricing. Great work on the installation. And the installers were nice and friendly. Highly recommend Thomas Hoffmann.
Response from the owner:Thank you, Steve! We truly appreciate your kind words and are glad to hear you had such a positive experience with our team and Thomas Hoffmann. Your recommendation means a lot to us!
Hoffmann came out the same day I called them because our AC was out. The technician, Ryan, was able to get the system running again, was polite and responded to my questions. We’re off to a good start!
Response from the owner:Thank you, John! We're glad to hear Ryan was able to help and that you’re off to a good start with your AC. We appreciate your feedback!
Thomas came over promptly I spoke with him about my concerns with my unit. Immediately got to work trouble shooting and resolved my issues. A+
Response from the owner:Thank you, James, for your kind words and for recognizing Thomas's promptness and dedication in resolving your concerns; we appreciate your feedback!
We have called Thomas Hoffmann many times and they are very prompt and very professional.
Response from the owner:Thank you, Vicki, for your kind words about Thomas Hoffmann's promptness and professionalism; we truly appreciate your feedback!
Not a customer, but witnessed one of their technicians have an episode of road rage in Clayton. I would be concerned about letting them into my house/business.
We really trust Thomas Hoffman AC and Heating. Nick Hoffman has serviced our units several times now and he is professional, knowledgeable and very easy to work with. He comes on time, so we don’t have to schedule a long waiting period. We would highly recommend this company.
Response from the owner:Thank you, Greg, for your kind words and for trusting us with your AC and heating needs; we’re glad to hear that Nick has provided you with such great service.
We’ve been looking for a locally owned small HVAC dealer for a few years. And we found it with Thomas Hoffmann Air Conditioning & Heating. We love their service technicians. They come on time, they know what they are doing, they don’t upsell you on every appointment and they like working for Thomas Hoffmann. A happy employee makes for a happy customer.
Response from the owner:Thank you, Mary, for sharing your wonderful experience with us; we're glad to hear you appreciate our technicians and their commitment to great service!
I called on a Monday morning as air conditioning was blowing warm air. They were able to come to my house very early afternoon and fixed the problem. Would highly recommend and will use them again.
Response from the owner:Becky thank you so much for your great review. We appreciate your business and your kind words.
Response from the owner:Thank you, Margaret! We appreciate your kind words and will make sure to pass along your praise to Nick for his excellent service.
I am very pleased with the service provided. , especially the quick response to my request . The technician came in themorning and had my cooling system repaired within an hour. Thank you !
Response from the owner:We're delighted we could promptly assist you on a Sunday morning and fix your cooling system efficiently. Thank you!
Here on time, worked fast. Always pleasant and great answering questions. Zach always does a great job.
Response from the owner:Thank you, Debra, for your kind words; we're glad to hear Zach made a positive impression and that you had a great experience with our team!
Extremely quick response for appointment and did quick fix for our furnace and heat is working great !
Response from the owner:Thank you for your kind words! We're glad to hear our team was able to respond quickly and get your furnace working great. We appreciate your feedback!
They were timely, polite, professional and they saved us from too much sweating. In a field full of pompous and arrogant technicians, these guys take the time to explain what is wrong and how they are correcting it. Other folks just assume you are incompetent but these folks take the time to educate. Cannot recommend highly enough.
Response from the owner:Thank you for your kind words! We truly appreciate your feedback and are glad we could provide you with a positive experience.
I would like to have a receipt for my payment which I did not receive. On a positive note he was very punctual very early actually he did his job and was very professional and I'm hoping and praying this took care of the issue thank you and I would not hesitate at this time to use your services
Response from the owner:Thank you, Mark, for your feedback and for highlighting the punctuality and professionalism of our team; we appreciate your support and will ensure you receive your receipt promptly.
Our experience with them was fantastic all the way through! Not only were they able to get to our business that day but the customer service from the phone call to the on-site service was professional and quick. We'll definitely be using Thomas Hoffmann Air Conditioning and Heating in the future.
Response from the owner:Thank you, Michelle, for your wonderful feedback! We're glad to hear about your fantastic experience and appreciate your kind words about our team's professionalism. We look forward to serving you again in the future!
I couldn’t be happier with the service from Thomas Hoffmann Air-Conditioning! From the moment I called, the team was professional, responsive, and truly knowledgeable. Thomas personally made sure everything was handled with great attention to detail. The installation was smooth, efficient, and the quality of the work exceeded my expectations. It’s rare to find a company that is both skilled and genuinely cares about their customers. I highly recommend Thomas Hoffmann Air-Conditioning to anyone looking for honest, reliable, and top-notch service. They’ve definitely earned a loyal customer!
Response from the owner:Thank you, Rick, for your kind words and for recognizing our team's hard work; we're grateful for your support and thrilled to have earned your loyalty!
Amazing service from Thomas Hoffmann! They made space in their schedule to come out the next day to fix our air conditioner. They were on time, honest and fixed the problem on the spot. Thank you!
Response from the owner:Thank you, Ashley! We appreciate your kind words about our team's service – it's great to hear we could help you so quickly.
Fast efficient service. Both of the gentlemen that came to my home were very help and informative not to mention polite. It’s difficult to get service advisers to appear at your home when scheduled most times they’re late or don’t show up at all. Not an issue with this team on time, clear diagnosis, quick repair. I would definitely use Thomas Hoffmann Air Conditioning again. I recommend them highly.
Response from the owner:Thank you, Anna, for your wonderful feedback! We're glad to hear that our team provided you with timely and helpful service, and we appreciate your high recommendation.
Response from the owner:Thank you, T! We're glad to hear that everything is running smoothly and appreciate your recognition of our team's effort.
What Is a BTU?
BTU stands for British Thermal Unit, a measurement of heat energy. Specifically, one BTU is the energy needed to raise the temperature of one pound of water by one degree Fahrenheit.
In the HVAC world, BTUs measure how much heat an air conditioner can remove or a furnace can produce in an hour. You’ll typically see systems rated in:
BTU/hr (BTUs per hour) – for furnaces and air conditioners
Tons of cooling – where 1 ton = 12,000 BTUs/hr
For example:
A 24,000 BTU AC unit removes 24,000 BTUs of heat per hour (equivalent to a 2-ton system).
A 100,000 BTU furnace delivers that much heat energy into your home each hour.
Why BTU Ratings Matter for St. Louis Homeowners
1. Comfort
A unit with too few BTUs won’t keep up during hot St. Louis summers or chilly winters. Rooms stay uncomfortable, and your system runs constantly trying to catch up.
On the other hand, too many BTUs lead to short-cycling—the system turns on and off frequently, reducing efficiency, increasing wear, and causing uneven temperatures.
2. Efficiency
Proper BTU sizing ensures your HVAC system runs at its most energy-efficient level. This keeps your utility bills in check, especially during high-usage months in July or January.
3. Equipment Lifespan
An improperly sized unit (over- or undersized) will likely break down early. Systems that cycle too often or run continuously are prone to excessive wear and tear.
How Many BTUs Does Your Home Need?
There’s no one-size-fits-all answer, but HVAC professionals use a Manual J load calculation to determine the ideal BTU rating for your home. This considers:
Square footage
Ceiling height
Number of windows and doors
Insulation quality
Sun exposure
Room use (kitchen vs. bedroom)
Ductwork design and air leakage
For example:
1,500 sq. ft. home × 20 BTUs = 30,000 BTUs (2.5 tons)
2,400 sq. ft. home × 20 BTUs = 48,000 BTUs (4 tons)
Important: St. Louis’ climate, with hot, humid summers and cold winters, makes proper BTU sizing even more critical. Undersized systems struggle during temperature extremes.
Standard HVAC System BTU Ratings
System Type
Typical BTU Range
Window AC Units
5,000 – 24,000 BTUs
Central Air Conditioners
24,000 – 60,000 BTUs
Gas Furnaces
40,000 – 120,000 BTUs
Heat Pumps
18,000 – 60,000 BTUs
Why You Shouldn’t Guess Your BTU Needs
Many online calculators oversimplify sizing. They ignore factors like insulation, room orientation, and how your home was constructed. That’s why a professional HVAC load calculation is essential for:
Energy savings
Improved comfort
Long-term system performance
Local Expertise Matters in St. Louis
At Thomas Hoffmann Air Conditioning & Heating, we don’t just sell you an HVAC system — we tailor it to your unique home and lifestyle. Our technicians are trained to assess BTU requirements precisely, considering local St. Louis weather patterns, your home’s age and insulation, and neighborhood trends (from Webster Groves bungalows to Chesterfield custom homes).
We proudly serve communities across the metro area — including Kirkwood, Wildwood, Maryland Heights, St. Peters, and Des Peres — with expert HVAC installations and BTU sizing assessments.
Schedule a BTU Load Assessment Today
Are you not sure if your current HVAC system is sized correctly? Are you experiencing hot or cold spots in your home? Let us help.
📞 Call us at (314) 471-7625 or schedule a consultation to determine your ideal BTU range. We’ll ensure your system is built for maximum efficiency, longevity, and year-round comfort.
