What Does a Furnace Tune‑Up Include?

To help you benefit from furnace maintenance, an HVAC contractor should include the following 7 steps in a standard tune-up checklist:

1. Checking thermostat: Improper thermostat settings can decrease home comfort and increase energy bills.
2. Tightening all electrical connections: Loose electrical connections can be hazardous.
3. Inspecting motors: Worn-out or broken motors can reduce the lifespan of your entire system.
4. Lubricating moving parts: Without lubrication, your furnace might need to consume more energy and possibly break down.
5. Checking and inspecting the condensate drain line: A clogged condensate drain line can cause water damage and increase your home’s humidity levels.
6. Checking system controls: Getting your system maintained before the heating season ensures that it will start, operate, and shut off as it should.
7. Checking connections, combustion, and the heat exchanger: All three in good working order allows your furnace to operate safely and efficiently.

At the very minimum, a contractor should follow this basic maintenance checklist to ensure that your furnace is functional and not excessively consuming energy.

For example, Four Seasons offers a 21-point furnace tune-up that includes:

1. Cycling the furnace: The technician will double-check that the furnace isn’t short cycling. A short cycling furnace leads to wasted energy and decreased comfort, as your furnace won’t reach your desired temperature.
2. Cleaning the blower: Having a dirty blower wastes fuel and reduces your furnace’s efficiency.
3. Cleaning or changing the filter: Regularly changing the furnace filter keeps your furnace from overheating and improves your indoor air quality.
4. Testing safety controls: A technician will test the safety controls in your furnace, protecting you from fires and carbon monoxide poisoning.
5. Testing temperature differential: Temperature differential is the difference between the outdoor and indoor temperature. Testing your furnace’s temperature differential verifies that it’s within the normal heating capacity range. An abnormal temperature differential can cause you to spend more than you need to on your heating bills.
6. Cleaning flame sensor: Your furnace has a flame sensor that turns the system on only when it confirms there’s a fire. However, when there is carbon buildup on the sensor, it will shut off your furnace even when there is a fire to ignite the gas.
7. Oiling the blower & inducer motor: The blower can seize and stop rotating without proper oiling. Furnaces cannot operate without a functional blower.
8. Testing amp draw to blower: When a technician measures how much power the blower is consuming, a high amp draw is a warning sign that the blower might break down soon.
9. Rating/setting furnace input: If the furnace input isn't precisely set, it will not provide the heat you’re looking for.
10. Testing amp draw inducer: The inducer clears combustion gases from a previous heating cycle. A technician will test the amp draw to the inducer motor with a meter to check it’s not high enough to start overheating.
11. Inspecting flue pipe: Your furnace's flue pipe vents gases outside. A corroded flue pipe or one with loose joints can cause the furnace to backdraft, allowing the combustion gases to enter your home.
12. Testing hot surface igniter: A hot surface igniter uses an electric current to heat up enough to auto-ignite gas. It can degrade if it stays on for extended periods after the gas ignites or if the surface temperature is too high.
13. Cleaning burners: Dirty furnace burners decrease the amount of heat in your home and prevent the system from evenly heating the area.
14. Tightening electrical connections: As mentioned above, loose electrical connections can be a home safety hazard.
15. Cleaning & adjusting pilot assembly: A dirty pilot assembly can be the reason why your furnace won’t stay on.
16. Cleaning exterior: Keeping the furnace clean prevents soot buildup.
17. Testing gas pressure: Ensuring the gas pressure isn’t too low will help keep your furnace as efficient as possible. Low gas pressure can increase the risk of overheating and damage to internal components.
18. Brushing & inspecting heat exchanger: A technician will confirm that the heat exchanger doesn’t have cracks or isn’t functioning. A cracked or dysfunctional heat exchanger can result in safety issues and an expensive replacement.
19. Testing for gas leaks: A furnace gas leak can circulate carbon monoxide throughout your home, with various adverse health effects.
20. Vacuuming burner compartment: A clogged burner compartment can reduce heat output, and the furnace will have difficulties starting up. Vacuuming the compartment will clean out any stuck debris.
21. Cycling condensate pump: High-efficiency furnaces use two heat exchangers to extract as much heat as possible and use colder exhaust/flue gases than usual, producing more condensation. The condensate pump traps and drains this condensation to prevent gases from entering your home. Cycling the pump lets the condensation correctly drain.

As you can see, each point in this 21-point furnace tune-up is vital for the safe operation of your heating system, not to mention your comfort and reasonable heating costs.