furnace not working

Fixing a Furnace That’s Not Working After a Power Outage

Few things are as frustrating as a cold and unwelcoming home on a chilly winter day. However, what if you’re among the unlucky homeowners who experience a power outage and find that your furnace refuses to kick back into action once the power is restored? The situation can quickly turn from inconvenient to downright exasperating. 

Let’s delve into the most common reasons why your furnace is not working after a power outage and then explore the troubleshooting steps to get your heating system up and running efficiently once again.

Safety Note

Before we start, it’s important to remember that if your furnace uses natural gas, propane, or oil, it’s crucial to follow proper safety procedures when inspecting or rebooting your system. If, at any time, you smell gas or suspect a gas leak, leave the house immediately and call your local utility company or emergency services.

1. Ensure your furnace is still switched on 

Sometimes your furnace is not working after a power outage for the most apparent reason – the interruption to the power caused the furnace to switch off. Some, but not all, furnaces have an on/off switch located near the furnace, so begin by looking for a switch and, if you have one, ensure your furnace is still turned on.

2. Check the circuit breaker

Your home’s circuit breaker protects the electrical system from overloading and tripping during a power surge. A prime example of that is during a power outage. If the circuit breaker has tripped, it can cause the furnace to shut off and may prevent it from turning back on. Even for homes with gas furnaces, a power outage means your furnace won’t work. 

Here’s how to check the circuit breaker when fixing a furnace after a power outage.

  1. Locate your circuit breaker panel: Circuit breaker panels are usually found in a utility room or basement, although in some cases, they may be outside the house. Ideally, you should know where your electrical panel is before you need to find it in an emergency!
  1. Open the panel: To open the panel, remove the cover by unscrewing the fasteners or flipping the latch.
  1. Identify the furnace breaker: Look for the breaker switch that controls power to the furnace. It may be labeled as “furnace,” “heat,” or something similar.
  1. Check the breaker switch: If the breaker switch is in the “off” position, flip it to the “on” position. If it’s already in the “on” position, flip it off and then on again to reset it.
  1. Check for other tripped breakers: If the furnace breaker switch was not tripped, check for other tripped breakers in the panel. Reset any tripped breakers by flipping them off and then on again.
  1. Close the panel: After resetting the breaker switch, close the panel cover and ensure it’s securely fastened.

3. Reset any GFCI outlets

If your furnace is not turning on after a power outage, check any Ground Fault Circuit Interrupter (GFCI) outlets, as they may have tripped during the power surge. A GFCI outlet, sometimes known as a Ground Fault Interrupter (GFI), is a type of electrical outlet with a built-in circuit breaker to help protect against electrical shock.

GFCI outlets are typically found in areas where water is present, such as bathrooms, kitchens, and outdoor spaces. After your power outage, check the GFCIs in your home and look for a small button on the outlet labeled “reset.” Press the button and see if it clicks and stays in place.

After resetting the GFCI outlet, press the “test” button to see if it trips and cuts off power to the outlet. If it does not trip, the GFCI outlet may be faulty and should be replaced. If the GFCI outlet works correctly, check other nearby outlets to ensure they also work.

4. Check the furnace safety lock 

Most modern furnaces have a safety lockout feature that shuts off the furnace if it detects a problem, such as a malfunctioning ignition system or a blocked vent. This lockout feature can be automatically activated during a power outage.

If you think the furnace safety lock may have kicked in, it will need to be reset. To reset your furnace after the power outage, you should:

  1. Locate the furnace’s power switch or circuit breaker and turn off the power to the furnace.
  2. Wait at least five minutes for the furnace to cool down and for any residual gas to dissipate.
  3. Find your reset button – it is typically located on the furnace’s control panel or near the blower motor. Consult your furnace’s manual for specific instructions on locating the reset button.
  4. Press and hold the reset button for several seconds. You may hear a clicking sound or see a red light flash, indicating that the furnace has reset.
  5. Turn on the furnace’s power switch or circuit breaker and set the thermostat to your desired temperature.
  6. Watch the furnace for a few minutes to make sure it starts up and runs smoothly.

5. Check the thermostat

If the circuit breakers are set, the power switch is on, all outlets are working, and the furnace safety lock has been reset, yet your furnace is not working after a power outage, the problem may not be your furnace – it might be your thermostat.

The first thing to do is to check if your thermostat has power. If it is battery-powered, ensure the batteries aren’t dead. If your thermostat is hardwired, double check the circuit breaker that powers the thermostat has not been tripped during the power outage.

Some thermostats default to “off” mode if the power is cut, so ensure your thermostat is set to “heat” mode. If it’s set to “cool” or “off,” the furnace won’t turn on. If the thermostat has a programmable feature, ensure it’s set to the correct schedule. Power outages can sometimes reset the thermostat’s programming.

Check the temperature setting on the thermostat and ensure the temperature is set higher than the current room temperature. If the temperature setting is lower than the room temperature, the furnace won’t turn on.

Finally, check the thermostat for dust or debris that could obstruct the temperature sensor or other components, and clean your thermostat if necessary.

6. Inspect the air filter

A clogged air filter can cause the furnace to shut off as a safety measure. Sometimes when a power outage occurs, the furnace registers a restricted airflow when it restarts. So, check your air filter and replace it if it’s dirty or clogged. 

If your furnace won’t turn on after a power outage, give us a call.

If you’ve gone through all of the steps above, and your furnace still isn’t working, your best bet is to call an HVAC professional to inspect and, if necessary, repair your system. 
Call Anderson Air today and rediscover the joy of a warm and cozy home!

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