HVAC Experts Reveal the $1 Incense Trick That's the Secret to Slashing Your AC Bill This Spring
It's an easy, inexpensive method to save money
As temperatures rise, so too do air conditioning bills. And, if your windows and doors aren't sealed correctly, you might find them doing so more than usual.
While these costs are an inevitable part of warmer weather, there is one easy and affordable trick you can use to check that your AC is working as efficiently as possible – and all you need is an incense stick.
Article continues belowWhy Drafts Are More Noticeable In Spring, and How to Spot Them
The incense stick trick is simple: Slowly pass a lit stick around window frames on a windy day. If the smoke flickers, you're losing money from failing seals. If you have one of these as part of your home fragrance favorites, then it's easy to get testing. If you don't, you can pick incense sticks very affordably from Amazon, with same-day or next-day delivery.
Josh Mitchell, HVAC Expert and Founder of AirConditionerLab, details that the main reason for new spring drafts stems from winter freeze-thaw cycles.
'Freeze-thaw cycles wear down seals faster than people expect,' he explains. 'During winter, caulk and rubber seals expand during warmer daytime temperatures and contract overnight when temperatures drop below freezing. That repeated movement creates hairline cracks that grow over time. UV exposure from winter sun also dries out sealants, making them brittle.'
'In many homes, especially those over 10 years old, I see seal breakdown within two to four seasons. By early spring, those gaps are already letting conditioned air escape.
'Even small openings around windows can increase cooling load by five to 15 percent, which is why people notice higher AC bills as soon as temperatures start rising,' or struggle to even keep a home cool in the first place.
And, as Patrick Gambel, Owner of General Heating & Air Conditioning, adds, the main issue is, 'Most homeowners don’t catch it right away, but those little openings are what lead to drafts and higher energy bills.'
How to Use the 'Incense Stick' Trick to Identify Drafts
All you need is an incense stick.
'The incense trick works because smoke reacts to even slight air movement,' continues Josh. 'I tell homeowners to turn off ceiling fans and hold a lit incense stick about an inch away from window frames, corners, and trim. Move slowly along the edges.
'If the smoke drifts sideways or gets pulled in a direction, that’s a leak. You can also test on a calm day with the AC running, since pressure differences will still pull air through gaps. It takes about five to 10 minutes to check an entire room and gives a visual result that’s easier to spot than using your hand.'
Most importantly, catching these failed seals early prevents costly repairs, as air leaks spell moisture, mold, and mildew.
'Warm indoor air hitting a cooler window frame can condense inside the wall or around the frame,' adds Josh. 'Over time, that leads to soft wood, peeling paint, and mold.
'Once the frame starts to break down, you’re no longer looking at a seal fix. You’re looking to replace parts of the window or the entire unit, which can cost $500 to $1,200 per window. Fixing the gap early with a $10 to $20 material avoids that progression.'
Jordan Benjamin, HVAC, Plumbing Expert, and the President of Done Rite Services, agrees. 'Catching a failing seal early prevents serious damage from occurring,' he says. 'Gaps in the seal lead to moisture intrusion, which causes wood to rot, insulation to deteriorate, and frames to warp.
'These kinds of issues can be expensive to repair, and if the damage is severe, a full replacement may be needed. It’s much easier and less expensive to replace failing seals as you notice them.'
How to Eliminate Drafts
Identifying gaps and cracks helps to trap air conditioning and keep your home cool.
Once identified, DIY draft proofing is easy.
'For quick fixes, I recommend removable weatherstripping for windows that open and close often,' suggests Josh. Rope caulk [such as the Frost King Fingertip Rope Caulk, available at Amazon] works well for seasonal sealing and costs under $10 per pack.'
If you're not so confident with DIY, you could also go for what Scott Levene, Vice President of Levco, refers to as the 'faster, uglier way' – shrink wrap.
'Shrink-wrap works on not-so-beat-up windows, and it doesn’t require as much precision or near-craftsmanship to install as caulk sometimes can,' he explains. 'It works like a cheaper, temporary storm window, stopping leaks and creating an air pocket with an insulating effect.'
Then, for windows, a door sweep or draft stopper, available at Amazon, blocks airflow at the bottom, where most leaks happen.
'If you find wider gaps, use low-expansion foam labeled for windows and doors,' continues Josh. 'It fills the space without pushing on the frame. A single can can seal multiple windows and costs around $6 to $10.' For this, we recommend the GE Big Gaps & Cracks Insulating Foam, available at Walmart.
'For smaller cracks, acrylic latex caulk is a good option and is easier to control than foam,' he adds. And importantly, Josh warns, don't overlook your outlets and switch plates on exterior walls, or all your attempts to weatherproof your windows will be in vain.
'I’ve tested homes where those spots alone accounted for noticeable airflow,' he says. 'Foam outlet gaskets cost a few dollars and take only a few minutes to install.
'Attic access points and baseboards along exterior walls are also common leak points. When you seal several small gaps, the combined effect reduces how often your system runs and helps maintain stable indoor temperatures.'
What to Shop
Below, you can shop from a selection of expert-approved draft proofing essentials – including caulk, expanding foam, and incense sticks, which you can also use as a quick way to make your home smell nice.
Each is suitable for differing factors, such as the size gap you need to fill, so make sure to assess yours individually before deciding on which will work best for you. Some, like the shrink-to-fit window kit and door sweep, are also conveniently removable, but will work just as well to keep your home warm and trap heat in winter as they will to keep it cool and trap air conditioning this spring and summer.
All prices were correct at the time of publication.
Whether checking for drafts or scenting my home, this is the incense I almost always use. It's affordable, effective, and high-quality, and this box contains an array of scents to suit any space and mood.
This rope caulk is designed for easy application and convenient removal, and extends to a length of 35 feet, providing ample material for sealing gaps and blocking drafts.
This draft stopper is designed to effectively reduce noise and drafts, and works on many doors and windows to prevent the leakage of air conditioning and heating in both summer and winter.
This expanding foam, available in a pack of two, expands to precisely fill any gaps and cracks up to one inch in size. With superior flexibility, it withstands building and material movement without compromising its seal.
These electric outlet sealers help to reduce draft and heat loss, and come in a simple and easy-to-use kit with enough for six standard electrical outlets. They stick well and last all season long.
This shrink-to-fit window kit saves up to 35% of heat and air conditioning loss, and all you need for crystal clear insulation is a standard hair dryer. One kit provides enough for nine standard windows.
Meet the Experts
Josh is an HVAC professional and founded AirConditionerLab in 2014 as a way of collating his HVAC findings and expertise in an easily digestible way for readers. He and his team now cover all aspects of home heating, cooling, and air quality.
Patrick is the owner of General Heating & Air Conditioning, an HVAC company in New Orleans, LA. He's been in business for over 40 years, helping individuals and families all over New Orleans stay comfortable in their homes year-round. With over four decades of hands-on HVAC experience in New Orleans homes, he's seen how small issues like this can turn into bigger problems if they're overlooked.
Jordan is an HVAC and plumbing expert and the President of Done Rite Services, an HVAC, plumbing, and electrical company in Tucson, Arizona. He has over two decades of experience in the HVAC trade, and has owned Done Rite Services since 2015.
Scott is the Vice President of Levco, a family-owned heating oil, propane, & HVAC business, which has been based in Trumbull, CT since 1980, and was originally founded by his grandfather. Under Scott’s leadership and with 18 years of hands-on experience, Levco has continued to expand its services.
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