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Winter brings cold weather and is the perfect time to bundle up and stay warm and cozy at home. But during those extremely cold snaps when cold air, wind, and snow drop temperatures below zero, furnace maintenance becomes more important than ever.


Your furnace is designed to heat your home and keep it comfortable and safe, but it has to work much harder to do that in sub-zero temperatures. Even a great HVAC system can still face struggles in ultra-cold weather if it isn’t maintained properly.


We may only get sub-zero temperatures for a few weeks a year in Colorado, but ensuring your furnace is working properly and is well maintained helps your house stay warm during those chilly weeks and avoids the system straining too much and causing issues during other parts of the year.


Taking proactive steps to prepare for cold weather and ensure your furnace is working properly can prevent any issues from occurring later when the cold snap hits.


Here are five ways to maintain your furnace in sub-zero temperatures:


Change Your Filter


changing furnace filter


Regularly checking and changing your air filter is one of the easiest and least expensive ways to ensure your furnace is working smoothly, no matter the weather.


It becomes especially important for maintaining your furnace in the winter when temperatures dip below zero. Filters can fill up twice as fast when temperatures as low, so you may have to change it more often than during the rest of the year.


When the filter gets dirty, it becomes more difficult for air to push through, which causes the system to work harder. Your furnace is already working harder in freezing temperatures, so a dirty filter only magnifies the problem.


When air has to work harder to push through a dirty filter, it creates more static pressure, which can cause problems throughout the HVAC system.


Check your furnace regularly to ensure air can get through. The filter needs to be changed if it is gray and covered in lint or if your home gets dusty quickly. If you shine a flashlight and no light gets through the filter, it is definitely time for a clean filter.


In most homes, especially during the super cold months, the furnace filter needs to be changed every month. Getting in the habit of regularly checking and changing your filter can prevent larger issues down the road, especially when the temperature falls.


Set Your Thermostat


setting thermostat in the winter


During most of the year, the most energy-efficient method for running your furnace is to use a programmable thermostat to adjust the temperature of the house throughout the day.


Automatically lowering the temperature at night when people are sleeping or during the day when no one is home limits the wear and tear on the furnace and prevents it from heating the house unnecessarily. But those guidelines don’t apply in sub-zero temperatures.


The constant temperature change causes the furnace to work harder and can make it difficult to get back up to the desired temperature. Once the temperature inside has gone down, it becomes very difficult for the furnace to heat the house again when the outside temperature is in the negatives.


Instead, the best way to maintain constant heat and keep your furnace running smoothly is to set the thermostat to one temperature and leave it running.


Having one temperature regardless of the time of day or who is home makes it easier for your furnace to keep up instead of constantly changing the temperature. When a cold snap or storm is on its way, set the temperature to a few degrees above its normal setting and then leave it or set your programmable thermostat to “Hold” mode.


Even a strong thermostat may struggle to reach the desired temperature when the weather is well below zero, so holding a constant higher temperature helps keep your house warm and makes things easier for your furnace.


Check Your Pipes and Ductwork


checking furance ductwork


It’s crucial to have clear pipes and ductwork at all times of the year, but especially when the weather is extremely cold. A blocked vent or loose duct could cause air to escape or block the flow of the furnace and cause the entire system to work harder, which increases the chances of damage.


As the temperatures start to drop, visually inspect the vents, pipes, and ductwork inside and outside your house. Remove any snow or debris from your exterior vent pipes and any furniture or other blockages from interior registers and air vents.


High-efficiency furnaces often have exterior exhaust vents near ground level, which makes them more likely to be blocked by ice or snow. Check the vents frequently, especially during winter storms, to ensure they are clear and the furnace can operate properly.


Ensuring the air has a clear path to easier move through the HVAC system makes things easier on the furnace as it works hard in sub-zero temperatures.


Get in the habit of checking that your interior vents are clear every season, especially if you rearranged furniture and moved something close to a vent. Make sure all the vents are open and that there isn’t dirt or debris blocking the warm air from coming into the room.


If you really want to set your furnace up for winter success, carefully remove the vent covers and wipe them with a damp cloth to remove dust and dirt. Warm air flows better through unobstructed, clear vents.


When the weather is extremely cold, the goal is to make airflow as easy as possible for the furnace.


Use Other Methods to Heat Your Home


fireplac instead of furnace


When temperatures are in the negatives, your furnace needs all the help it can get. Sub-zero temperatures can prevent the furnace from heating the house to your desired temperature.


The furnace is still the main source of heat in your home, but you can take other steps to keep your home warm in subzero temperatures and reduce the load on the furnace.


If possible, reverse your ceiling fans to keep warm air moving and circulating through the house. Use space heaters in areas you are actively using, such as a home office or living room, or keep a fire burning in your fireplace.


Install weather stripping around doors and windows to prevent warm air from escaping or cold air from getting in, especially if your home is older or drafty. Wear layers and bundle up with blankets.


These small actions add heat to the house and can supplement what comes from your furnace to reduce wear and tear.


Take steps to prevent the warm air from leaving your home by limiting how much you open exterior doors and windows and by keeping your garage door closed.


Every time an outside door opens, it lowers the temperature of the house and makes the furnace work harder to get the temperature back up. Close your curtains and blinds to prevent warm air from escaping through closed windows.


Perform Preventative Maintenance


preventative maintenance


The best way to ensure your furnace works through all the ups and downs of Colorado weather is through regular, preventative furnace maintenance.


Calling your local furnace repair professionals like the team at Stone Heating can give you peace of mind that your furnace will run throughout the lower temperatures.


Regular inspections and electric furnace maintenance ensure the system is running smoothly without any issues or leaks that could prevent it from keeping your house warm when the temperatures drop.


Many people don’t think they need a furnace tune-up if their system is working well. But just because your furnace heats your home doesn’t mean there aren’t other, smaller issues that you might not notice.


A damaged or inefficient furnace can still work, but it likely won’t last as long or be as effective, especially in extreme temperatures. Preventative maintenance treats issues before they grow. If the HVAC professional finds any issues or damage to the system, they can repair them much more easily before the cold weather sets in.


Instead of finding yourself in an ultra-cold house with a faulty furnace in sub-zero temperatures, you can rest easy knowing your furnace is in great working condition. Preventative maintenance saves you the stress and cost of an emergency furnace repair.


Aside from regular professional maintenance, there are steps you can take to ensure your system is running well. Check for leaks and regularly check all of the vents to make sure warm air is coming out.


Change the battery of your programmable thermostat so that it doesn’t stop working during cold weather. Pay attention to any noises or smells coming from your furnace, which could signal bigger issues.


Sub-zero temperatures are part of winter living in Colorado. Following these five ways to maintain your furnace in negative temperatures can keep your home warm and safe, no matter what the weather brings.