When it comes to your HVAC system, your “to-don’t” list is just as important as your to-do list. Avoiding these common mistakes and poor habits can help prevent stress related to your HVAC system.

Here are the top six activities to put on your HVAC “to-don’t” list this holiday season.

Crank up the heat

It is important to make sure your home is comfortable and livable during the coldest time of the year but resist the urge to turn the thermostat up all the way. This will help keep your energy bills down and lengthen the operating life of your furnace.

Ignore your humidifier

Winter is typically associated with low humidity and adding a humidifier is the best way to deal with this. But a humidifier is not a set-it-and-forget-it piece of equipment. You can end up with moisture problems when you least expect it. Monitor areas like your basement for too much moisture and make adjustments if needed.

Leave old insulation on ductwork

If you have ductwork passing through unheated spaces, it might already be insulated (if not, another “to-don’t” would be to ignore this situation – add insulating it to your to-do list!). Insulation degrades over time, causing heat to be transferred from your ductwork into this unheated space, wasting energy and costing you more.

Run your furnace with dirty ductwork

Every time your furnace comes on, it circulates the dust and other particles that have accumulated in your ductwork. With extra time indoors, your family is exposed to more allergens, dust, dander, and germs. Even if you have used your central system for summer, the higher temperature from your furnace provides the ideal conditions for bacteria to multiply.

Use your mechanical room for storage

Mechanical equipment like furnaces and water heaters require space around them for proper operation and maintenance. For anything burning fuel, a lack of oxygen causes incomplete combustion, which can produce carbon monoxide. So for your family’s safety, it is better to have a messy living room than a crowded mechanical room.

Run an untuned furnace

After everything that has happened throughout the year, a furnace tune-up might be lower on your to-do list. But running your furnace for another year without regular maintenance can cause more problems, making this a critical “to-don’t” for winter.