As the temperature drops, it’s time to make sure your heating system is up to the task of keeping your home warm and cozy. Preparing your HVAC for winter involves a few simple steps that can improve efficiency, prevent breakdowns, and ensure safe operation during the cold months. In this guide, we outline 10 important steps to prepare your HVAC system for winter. From furnace maintenance to thermostat adjustments and even tending to your AC unit, these tips will help you head into winter with confidence.
Starting winter with a fresh HVAC filter is a must. Over summer, your HVAC filter may have trapped dust, pollen, and debris. A clogged filter will reduce airflow, making your furnace work harder to push warm air through your home. Before the heavy heating season begins, put in a new filter (or clean it if you have a washable one). During winter, continue to check the filter monthly. A clean filter not only helps your furnace heat more efficiently, but also improves indoor air quality. Bonus: A clean filter can also protect your furnace from overheating due to restricted airflow.
It’s highly recommended to get a furnace or heat pump tune-up each fall. During a tune-up, an HVAC technician will inspect and clean critical components of your heating system: burners, heat exchangers, ignition system, blower motor, and more. They’ll also tighten electrical connections and ensure the system is running safely and efficiently. This preventive check can catch issues like a cracked heat exchanger or weak igniter before they cause a mid-winter breakdown. According to Carrier, an annual furnace tune-up helps avoid dirt buildup problems and allows contractors to address potential issues proactively carrier.com. Many HVAC companies offer affordable fall maintenance specials – it’s worth the small investment for peace of mind (and potentially lower heating bills due to a well-calibrated system).
Don’t wait until the first frigid night to discover your furnace isn’t working properly. On a cool fall day, switch your thermostat to heating mode and set a temperature a few degrees higher than the current temperature. Verify that:
The furnace or heat pump kicks on,
Warm air is blowing from the vents,
And the system continues to run until the set temperature is reached.
Listen for any strange noises (like banging or screeching from the furnace) and note any odd smells. It’s normal to smell a slight burning dust odor at first – that’s dust burning off the heat exchanger after months of disuse. It should clear quickly. If the furnace doesn’t start or you hear loud booms/scraping, there could be an issue (consult our furnace troubleshooting guide for common problems, or call a technician).
While not directly part of the HVAC unit, your home’s insulation and air sealing play a huge role in winter comfort. Even a top-notch furnace will struggle if your home leaks heat. Check for drafts around windows, doors, and any penetrations in walls or ceilings (like plumbing or electrical openings). Use weatherstripping or caulk to seal leaks. In the attic, ensure you have sufficient insulation to prevent heat rising out of your living space. Well-insulated and sealed homes retain heat better, meaning your furnace can run shorter cycles. Also consider closing fireplace dampers when not in use, and using draft stoppers for under-door gaps. These small steps lighten the load on your heating system significantly.
Go through each room and ensure that heating vents (registers) and return grilles are not blocked by furniture, rugs, or curtains. Your furnace needs free airflow to distribute heat evenly. During summer rearrangements or as you brought in fans, some vents might have become obstructed. Open all supply vents – closing too many in an attempt to force heat elsewhere can actually harm airflow balance and the furnace. Also, vacuum dust off vent grilles if you haven’t in a while. If you have radiators or baseboard heaters instead of forced air, make sure nothing is pressed up against them and dust them off so heat can radiate freely.
Take a look at your thermostat’s programming (if it’s programmable). Adjust the schedule for winter: e.g., set it to a lower temperature at night or during work hours to save energy, and a comfortable temperature when you’re home in the evenings. If you have a smart thermostat, ensure it’s switched to heating mode and update any temperature ranges or geofencing features for the season. You might also consider enabling any features like “adaptive recovery” (which pre-heats your home to reach the target temp by wake-up time efficiently). If your thermostat is old or inaccurate, upgrading to a programmable or smart thermostat can be a great winter project that leads to savings. As a general rule, setting the thermostat to around 68°F when home and lowering it a few degrees when asleep or away can save a lot on heating costs over the season.
Your central air conditioner’s outdoor condenser unit will be idle over winter. It’s wise to prepare your AC for its off-season:
First, turn off the power to the AC condenser at the service disconnect or breaker. This prevents it from accidentally running on an unusually warm winter day and also protects against electrical issues.
Clean away any leaves or debris around the unit. Yard debris can trap moisture against the unit and invite rust.
Place a cover over the top of the unit (a piece of plywood weighted down can work) to keep falling leaves and ice out. However, do not completely seal the unit with a waterproof tarp – this can trap moisture and encourage mold or rust. You want some airflow. A dedicated AC cover that breathes, or even leaving the sides open, is recommended.
If your AC unit has any water drain hose, ensure it’s drained so it doesn’t freeze and crack.
Important: If you have a heat pump, do not cover it at all. Heat pumps run during winter, extracting heat from outside air, and they need full airflow. The Department of Energy specifically notes that you should not cover the outdoor unit of a heat pump during winter, as it will prevent proper heating operation energy.gov.
For window AC units: it’s best to remove and store them for winter to reduce drafts. If you must leave a window unit in place, consider using an insulated cover over it to block cold air (and make sure the area around it is well-sealed).
Winter means closed windows and running fuel-burning heat appliances, so now is the time to ensure your carbon monoxide (CO) detectors are functioning. Test each CO detector in your home and put in fresh batteries (or replace units older than 5-7 years as per the manufacturer). A properly tuned furnace should burn fuel cleanly, but if something goes wrong (like a cracked heat exchanger or vent blockage), CO could leak into your home – and it’s odorless and dangerous. CO detectors are your last line of defense. Also test your smoke alarms while you’re at it. If you have a gas furnace, make sure you know where the furnace’s emergency shut-off switch is and that it’s accessible. Safety first!
If you have a high-efficiency furnace or boiler, it likely has PVC vent pipes that exhaust out the side of your house. Ensure those external vent pipes are clear of any obstructions like leaves, nests, or debris. During winter, you’ll also need to keep an eye on them that snow doesn’t drift up and block them. For furnaces that vent through a chimney, it can be wise to have the chimney or flue checked for any blockages (like creosote buildup or bird nests) before heavy use. A blocked flue can cause poor combustion or CO buildup. For heat pumps and outdoor units, clear away any obstructions around them. They need airflow and will also create condensate (water) that drains – make sure drain lines are clear.
While not exactly a “prep step,” late fall is actually a smart time to evaluate if your heating system needs an upgrade. If your furnace is 15-20 years old or your heat pump is an older, inefficient model, you might save money (and avoid a surprise breakdown) by upgrading to a new high-efficiency unit before winter really kicks in. Newer furnaces are safer and often 15% (or more) more efficient than old models, and upgrading can also qualify for energy rebates in many areas. Similarly, if you’ve been relying on a bunch of space heaters due to cold spots, it may be time to improve your HVAC setup (like adding ductwork, improving insulation, or installing a ductless unit for targeted heating). For more on efficient upgrade options, see our guide on Upgrading Your HVAC System: Energy-Efficient Options.
Taking the time to prepare your HVAC system for winter can pay off with fewer problems and lower heating bills.
Most of these steps are easy DIY tasks that require little more than time and attention.
By replacing filters, checking your furnace, sealing your home, and scheduling a professional tune-up,
you’ll set yourself up for a warm and worry-free winter.
Once everything is set, all that’s left is to enjoy the cozy indoors while the weather outside turns chilly.
Stay warm, stay safe, and don’t hesitate to call a qualified HVAC professional for tasks you’re not comfortable with.
A little preparation goes a long way toward making winter comfortable and stress-free. ❄️🔥🏡
Q1: When should I start preparing my HVAC system for winter?
Begin preparations in early fall, before the first cold snap, to ensure your system is ready for heavy use when winter arrives.
Q2: How often should I replace my furnace filter in winter?
Replace filters every 30–60 days, since they get dirty faster when systems run continuously during cold months.
Q3: Can I do HVAC winter prep myself?
Yes. Basic tasks like changing filters and checking thermostats can be DIY.
However, professional inspections are strongly recommended to catch issues before they cause breakdowns.
Q4: How do I know if my furnace is winter-ready?
Test your furnace by running a heating cycle before winter.
If you notice strange noises, gas smells, or uneven heating, schedule professional service immediately.
Q5: Does winter HVAC prep save money?
Yes. A well-prepared HVAC system can save up to 15% on heating bills while also preventing costly breakdowns and emergency repairs.
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