8 Ways to Prepare Your Furnace for Winter

repair technician removing furnace service panel

To quote Ned Stark from Game of Thrones, winter is coming. Keeping yourself warm shouldn’t be a problem, as your furnace will take good care of you. But after being switched off during the warmer months, your furnace might need some assessment after its well-deserved rest. To make your life easier, we’ve come up with 8 ways to prepare your furnace for winter. 

Unless you’re in North Alaska, your furnace will be switched off during the warmer months of the year. Before restarting your furnace, you should check on the air filter, look for holes in the ductwork, and remove dust that has built up in the air vents. 

We’ll explore all the important measures to set up your furnace, signs it needs to be replaced, and more. 

8 Ways to Prepare Your Furnace for Winter

Before performing any specific checks, we recommended taking a quick visual inspection first. Your furnace may be installed in a laundry or equipment room, so be sure to remove items that have stacked up around the furnace. You should also remove any flammable materials you might’ve forgotten about. Finally, make sure the combustion air duct is clear of any obstruction. This duct allows the furnace to pull in air and function as needed. 

After this inspection, you can run the following checks and help your furnace get back to full fitness after a laid-back summer. 

Change the Filter

Senior Man Changing a Dirty Air Filter in a HVAC Furnace
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Changing the filter inside the unit is one of the most important measures to ensure your furnace’s longevity. They’re tasked with trapping particles to keep your unit clean, prevent indoor air contamination, and prevent clogs. If kept unchecked, dirty filters can:

  • Restrict airflow and cause the system to overheat
  • Force the fan motor to overwork (consume more energy)
  • Clog the ductwork system
  • Reduce indoor air quality, possibly aggravating respiratory problems, such as asthma

But how can you be sure that your filter needs replacement or not? You can simply remove it and hold it up to a light source. If you barely see any light passing through the filter, then it’s definitely time for a replacement. 

To ensure maximum efficiency during the heating season, check the filter monthly and replace as needed. We recommend the use of filters with a high MERV rating. MERV stands for maximum efficiency reporting value, and measures how effective a filter is at removing air particles. The higher the rating, the more efficient the filter is. 

Check the Furnace Control Board

Carefully remove the front or access panel to inspect all electrical connections for signs of corrosion. If you own a soft brush suitable for such tasks, you can gently remove dust from the electronic components. Be careful not to loosen any electrical terminals in the process. 

To be on the safe side and prevent any damage, we recommend letting an HVAC expert do all the cleaning. 

Oil the Furnace Blower

In general, you need to oil the blower motor once a year to maintain performance. This component ensures the unit’s effectiveness in distributing hot air to your rooms. After being switched off for several months, the blower may need to be oiled before restarting. 

You have two options:

  • Spray a lubricant directly into the oil ports. You can purchase lubricant sprays in any local hardware store. 
  • Inject lubricant into the ports with a grease gun (2 or 3 drops)

If strange noises keep coming from the blower even after oiling the ports, call an HVAC pro. 

Check for Leaks

For once, we’re not talking about water leaks. Air and gas leaks are a much bigger problem for these heating systems. 

You should inspect the ductwork system for holes or gaps that can result in wasted heat. Sealing air leaks is key to maximize your furnace’s performance and ensure proper airflow. Additionally, you won’t waste any energy to heat loss. Here are some signs of an air leak you should look out for:

  • High energy bills: If there’s an air leak, your furnace will have to work much harder. This extra work puts a strain on your unit, which consumes more energy to keep running. Unsurprisingly, you’ll notice an increase in your energy bills. 
  • Higher dust levels: Leaking duct systems can pull in dust that’s built up around them, distributing it throughout your home. 
  • Uneven heat distribution: If you notice that some parts of your home are colder than others, then heat isn’t being distributed evenly. This is another clear sign of gaps or holes in the ducts

If you own a natural gas furnace, then you should regularly check for gas leaks. Inspect the gas lines and listen closely for any hissing sound, indicating a gas leak. You should activate your sense of smell to search for leaks. Similar to butane gas, gas producers add mercaptan to furnace gas to let you know there’s a leak. 

Mercaptan is an organic gas that’s composed of carbon, hydrogen, and sulfur. If you smell rotten eggs, that’s not someone preparing a bad meal. This is the smell of mercaptan letting you know there’s a gas leak. You can also check for a hissing sound of gas escaping through the gas lines. 

In any case, you must switch off the unit immediately and contact a local HVAC professional. To stop the leaks, the pro will most likely use a liquid sealant or heavy-duty aluminum foil. 

Clean the Ducts and Vents

Cleaning air ducts
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Air ducts are highly important for any heating system. Furnaces use them to circulate heated air throughout your home. Clean and properly maintained ducts ensure hot air gets circulated effectively, and maintain good indoor air quality. 

In contrast, ducts with high levels of dust restrict air flow and make it difficult for your furnace to distribute heat. This extra struggle can raise utility bills. To avoid such problems, you should clear registers and return vents before the heating season begins. You can use a wet cloth – not soaking wet – to remove dust off the vents and ducts. You should also remove furniture or drapes that block the openings and restrict airflow. 

Test Carbon Monoxide Detectors

Produced by furnaces and similar heating systems, carbon monoxide (CO) in enclosed spaces can be very dangerous and poisonous. CO detectors will make loud beeping sounds when levels start reaching dangerous levels. 

If your detectors are operated by batteries, the first thing you should do is check if they need to be replaced. After inserting fresh batteries, test the detectors to make sure the beeping alarm sound is loud enough for you to hear. 

But if the detectors are frequently damaged or not functioning properly, we recommend replacing them before restarting the furnace. 

If you’re buying new CO detectors, the Environmental Protection Agency recommends devices that are certified to the current Underwriters Laboratory (UL) standard 2034. Just check for a UL certification mark on the packaging, which shows that the product has been tested to nationwide sustainability and safety standards. 

Switch On the Thermostat

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What better way to test the furnace than by actually switching it on? But before that, check the wire connections under the cover to ensure every wire is properly attached. If you haven’t done so already, replace the batteries with fresh ones. 

If everything checks out, you can take the following steps:

  • Switch the thermostat setting to heat mode (switch it on)
  • Set the temperature a few degrees above the current room temperature
  • You should hear the system start in a minute or two 
  • There may be a temporary odor as the furnace burns away dirt and dust build-up inside. This is normal as dust settles on the heat exchanger when it’s not activated. 
  • If the unit doesn’t switch on, makes strange noises, or keeps releasing a burning odor, switch off the furnace immediately and schedule a professional maintenance

Overall, switching on the thermostat and going through this checklist gives you a better chance of addressing a problem before it gets worse. 

Schedule a Professional Inspection

There are certain measures that only a trained, HVAC professional should take. In other words, cleaning certain parts of the furnace is not DIY-friendly. 

The first thing the expert will do is replace your thermostat if needed. You can’t regulate temperatures and switch on the furnace with a damaged one. The expert will then proceed by cleaning the core components of your furnace: 

  • Heat exchanger: This part of a furnace tends to suffer from frequent dust buildup, and should be brushed and vacuumed. Why can’t you do this yourself? Inspecting, removing, and cleaning the heat exchanger requires special tools and training. 
  • Blower assembly: Ideally, it should be cleaned about twice a year. The openings of the blower tend to become blocked with dust or dirt. Letting pros clean this component will help minimize respiratory problems (asthma, allergies, etc..)
  • Burners: They may be connected through slots or wings. The pro will need to take them apart before cleaning them. Doing this yourself can damage the components and keep the furnace from working properly. 

Signs Your Furnace Needs Replacement

After many years of regular heating, your furnace may have passed its peak usage or performance levels. Basic maintenance or winter preps are no longer enough for the unit to run properly. The following signs will highlight the furnace’s drop in performance levels and your need for a replacement:

  • Unusual noises: They can range from popping, rattling, or humming. Any of these strange noises is a sign of improper functioning. 
  • Increase in energy bills: A steady increase in energy bills means your furnace is consuming more energy than normal. This occurs when the unit is not able to function efficiently. 
  • Uneven heating throughout the house: This is when certain parts of your home are colder than others, or not there’s not enough warm air distributed to match your thermostat temperature. 
  • Poor air quality: You’ll notice this if or when respiratory problems among your family aggravate, or there’s more dust and particles distributed throughout your rooms. 
  • Frequent repairs: If your furnace is more than 15 years old, then it is time to consider a replacement. Constant repairs to try and extend its lifespan may do more harm than good. 

More Ways to Winterize Your Home

Worker Spraying Blown Fiberglass Insulation between Attic Trusses
Photo Credit: BanksPhotos / Canva Pro / License

If you live in one of the northern states such as North Dakota, you know how harsh winters can get. Even with the furnace switched on, you may find yourself putting on extra layers of clothes to stay warm. Fortunately, there are extra measures you can take to winterize your home and keep the cold air outside. 

  • Proper insulation: If your attic is properly insulated, hot air from your rooms will not rise to the roof area. It will also keep the water pipes from freezing. 
  • Weatherproof doors and windows: Add weatherstripping around the perimeter of your windows and caulk any holes around them. This keeps cold air from entering your home. You can also add doorstrip to seal the gap between the bottom of the main door and threshold. 

There are also some outdoor measures to consider, just to protect your property from any winter damage. It’s smart to shut off the outside valve and store the hose away to keep it from freezing. You should also hire gutter cleaning pros to remove debris such as dry leaves. This keeps your gutters from getting clogged and frozen during the winter.  Finally, you should trim the tree branches to keep them from landing on your roof during a storm. 

FAQ About Furnace Maintenance

Does a furnace have an emergency switch? 

HVAC professionals would normally install an emergency ON/OFF switch for natural gas furnaces. This isn’t to say that other furnace types are 100% safe, but gas problems such as leaks can be far more dangerous. 

The emergency cut-off for a gas heating unit is typically installed on the wall in close proximity to the furnace. It is often red in color and marked “Emergency”. 

What are the current AFUE standards for residential furnaces? 

AFUE stands for annual fuel utilization efficiency, and allows us to determine the efficiency of a furnace. The higher the AFUE rating, the higher the efficiency. The Department of Energy has regulated the energy efficiency of residential furnaces to meet these minimum AFUE ratings:

  • Gas furnaces = 80%
  • Oil furnaces = 80%
  • Electric furnaces = 78%

How important are carbon monoxide detectors in your home? 

The most obvious reason is to warn you of high CO levels in your house. Carbon monoxide isn’t just produced by furnaces, but by stoves and fireplaces among others. The Consumer Product Safety Commission (CPSC) recommends that every home should have carbon monoxide detectors installed. The number of detectors required depends on the size of your home. 

Seeking Warmth? Revitalize Your Furnace

As the cold weather creeps in, homeowners should prepare the furnace for a busy season ahead. From the furnace filter to the programmable thermostat, these are key components of heating systems that need to be refreshed. 

After performing all the necessary measures, it’s highly recommended to hire an HVAC technician for a proper furnace tune-up. You will not save money by taking up risky maintenance tasks and damaging your HVAC system. 

To avoid freezing during a winter storm, hire a local HVAC professional to get your furnace running efficiently. 

Main Photo Credit: BanksPhotos / Canva Pro / License

Jeffery Keusseyan

Jeffery Keusseyan is a writer with a knack for research and handiperson skills. He enjoys writing about home improvement projects and efficient ways to maintain your home exterior.