Furnace Maintenance Checklist

Tech fixing furnace

To prolong the life of your furnace and ensure its optimal performance during cold winter days, it is essential to conduct regular maintenance. We recommend maintaining your furnace before the cold weather season to help improve its performance. 

Homeowners can take many simple steps to prepare their furnaces for the cold weather season. However, there is some maintenance that must be performed by a professional. Ontario homeowners may consider Enercare’s furnace maintenance plan to receive annual furnace maintenance by a professional technician. 

Review the following checklist to help understand how to maintain your furnace. 

Maintenance That Homeowners Can Perform

1. Replace Furnace Filter

The furnace filter collects common contaminants like dust and animal hair. All furnace filters have a MERV rating, which indicates how many microns a furnace can collect. MERV ratings typically range from one to sixteen, with a higher rating indicating that fewer particles can pass through the filter. With that in mind, filters with higher MERV ratings must be replaced more frequently than filters with low MERV ratings.

On average, Enercare experts recommend replacing your furnace filter every three months. A dirty air filter prevents efficient airflow through the HVAC system and thus reduces the system’s performance and may cause the system to overheat. Additionally, replacing your furnace filters regularly throughout the year helps maintain healthy air quality in the home.

2. Check Thermostat

Turn on the thermostat and wait for the furnace to turn on. If it shuts off after a few minutes, the furnace may be short-cycling, which is typically a result of the furnace not having enough airflow (possibly due to a dirty filter or plugged vents). Consult a professional for inspection if this occurs. 

Use a portable temperature sensor to ensure the temperature indicated on the thermostat is accurate. If your thermostat is set to a schedule, test to see if it turns off and on accordingly. 

If your home has a smart thermostat, it is important to check the device for any wireless connection or necessary software updates. Manually restarting the device to get it back online can troubleshoot this problem. Double-check that the temperature and schedule are configured to your desired settings. 

3. Check Air Registers, Dampers, & Ductwork for Airflow

Ductwork is essential to spreading heat throughout the home. Any air leaks or deterioration reduces their efficacy. Air leaks in the ductwork may result from physical damage or rust-induced holes. Most ductwork is located above or behind drywall and requires professional assistance to inspect should there be a significant problem. However, homeowners can pay attention to all registers (where your ductwork expels air) and any visible ductwork (often found in the basement) for clear signs of deterioration that could cause air leaks. Furthermore, after turning on your furnace for the first time in the season, our expert recommends checking all dampers to ensure they are open and letting warm air out.

During regular maintenance, a technician will check the airflow between the furnace and air ducts to determine a temperature rise. The temperature rise references the difference between the return air coming into the furnace and the supply air exiting through the filter and up into the ductwork.

The technician will monitor the temperature rise to ensure it is within the furnace manufacturer’s specifications and confirm enough airflow is processed through the system.

4. Replace Humidifier Pad

Usually, a central humidifier will be mounted on the furnace system. In climates with particularly dry winter air, humidifiers help maintain enough humidity in the home and reduce dry air-related skin problems, breathing problems, or damage to wood furniture and flooring. 

The most common type of central humidifier is a flow-through drip-style humidifier that works through evaporation. These humidifiers have absorbent pads that water flows across. 

During frequent use, the humidifier pad can become clogged and calcified. Our expert recommends that homeowners replace the absorbent pads with the same frequency as furnace filters. During this process, they also recommend cleaning the humidifier cabinet where the absorbent pad is located to remove mold or mildew. 

Professional Maintenance

1. Clean and Inspect Burners & Flame Sensor

The furnace burner burns air and fuel to generate heat. The burners in your furnace should always produce a blue flame. A yellow flame could be a potential sign that your furnace is generating an excess of carbon monoxide or may indicate a gas leak. This component may cause soot and condensation, which, if not cleaned regularly, can reduce the lifespan of your furnace. 

Most furnaces produced within the past fifteen years have burners sealed within the system. Therefore, they are only visible with professional assistance. 

The flame sensor indicates whether the furnace is functioning correctly. Because it is a part of the same component, it should also be removed and cleaned with the burner. 

Homeowners in Ontario can check out Enercare’s Furnace Protection Plan to cover repair and replacement costs of flame sensors, blower motors, boards, and many other furnace components.

2. Inspect the Heat Exchanger 

The most common cause of complete furnace failure is damage to the heat exchanger behind the burners. The furnace is deemed unsafe and needs to be replaced if the heat exchanger has deteriorated. A technician will inspect the heat exchanger during maintenance to confirm it is in good condition. It is not recommended for a homeowner to investigate their heat exchanger.  

Parts to Inspect if Your Furnace is 15 Years or Older

Furnaces have come a long way in the past fifteen years. Many maintenance steps have been eliminated with the updated manufacturing of newer furnaces. If your furnace is more than fifteen years old, the following steps should also be involved in regular furnace maintenance. 

  • Lubricate Blower and Inducer Motors: Inducer and blower motors should be oiled occasionally. If your technician knows you have an older furnace, they will inspect these parts to determine if they need lubrication.  Modern furnaces do not require this. 
  • Inspect Blower Belts: A technician may also remove the blower belts from pulleys to inspect for cracks or deterioration. Again, modern furnaces will not require this as they have direct drive or geared motors. 

Call in a Pro

Homeowners can get ahead of the cold weather season by taking simple steps to maintain their furnaces, like thermostat inspection, filter replacement, and overall system cleaning. That said, most regular furnace maintenance should be left to a professional. 


Enercare technicians are ready to help Ontario homeowners with HVAC maintenance or repair needs. Contact the furnace experts at Enercare today and prepare your home for the upcoming heating season.