Resetting a Gas Furnace? Here's How

Is your gas furnace on the fritz? Dealing with nagging error codes or just not firing up like it used to? Before calling in the pros, try resetting it yourself first. Resetting a gas furnace is a fairly straightforward DIY task that can get your heat flowing again and save you some cash. This comprehensive guide will walk you through everything you need to know to successfully reset your gas furnace.

Why Reset a Gas Furnace?

There are a few common reasons you may need to reset your gas furnace:

• The furnace is overheating - Gas furnaces have a high limit switch that trips when the furnace gets too hot. This switch shuts down the burner to prevent damage. Resetting the furnace resets this safety switch.
• The burner flames out - Issues like a clogged fuel line, faulty igniter or dirty flame sensor can cause the burner flames to go out. A furnace reset attempt may relight the burner.
• A power outage - After a power outage, the furnace may need to be reset to get it igniting properly again.
• Tripped circuit breaker - If the circuit breaker trips, it cuts power to the furnace necessitating a reset.

Resetting a gas furnace essentially provides a fresh start, resetting any tripped safety switches and initializing the ignition sequence. It's a handy troubleshooting step before calling a professional.

How Gas Furnaces Work

To understand why resetting a furnace can help, it helps to know a little about how gas furnaces operate. Here are the key stages:

1. Thermostat calls for heat - Signals the furnace to start heating cycle
2. Draft inducer fan starts - Pulls combustion gases through vent
3. Gas valve opens - Allows gas to flow to the burners
4. Igniter heats up - Ignites the gas at the burners
5. Flame sensor confirms ignition - Signals gas valve to remain open
6. Blower starts circulating warm air - Through home's ductwork
7. Thermostat satisfied - Stops call for heat, ending cycle

Issues like a faulty igniter, dirty flame sensor or tripped safety switch can disrupt this sequence. Resetting gets the furnace ready to initiate the cycle again.

How Often Should I Reset My Furnace?

There is no set timeframe for resetting a furnace. Only reset it when troubleshooting specific operation problems. Resetting unnecessarily can shorten furnace component lifespans. Here are some general resetting guidelines:

• Reset after any power outage, circuit breaker trip or unexpected shutdown
• Reset once initially when experiencing ignition or shutdown issues
• Reset a second time if symptoms persist after first reset attempt
• Reset annually before winter as part of seasonal maintenance
• Avoid resetting repeatedly over a short timespan

Excessive resetting indicates an underlying problem needing professional diagnosis and repair.

When to Reset Your Gas Furnace

Some signs that indicate your gas furnace needs resetting include:

• The furnace isn't turning on at all
• The blower runs but the burner isn't igniting
• You smell gas but the furnace isn't firing up
• The furnace keeps shutting off unexpectedly
• You hear the furnace trying to ignite repeatedly but failing
• The furnace is producing some heat but not reaching your set temperature
• The furnace is short cycling - turning on and off frequently

Before resetting your furnace, always turn the thermostat to "off" first. Resetting with the thermostat on risks damaging the heat exchanger.

Evaluating When to Reset

While the signs above indicate resetting may help, consider the following before resetting:

• Have there been any power outages in the area recently?
• When was the last time the air filter was changed?
• Does the thermostat seem to be working properly?
• Do you smell any odd odors around the furnace?
• Have there been any loud noises from the furnace lately?

Thinking through questions like these can provide clues to whether resetting alone will remedy the problem.

Locating the Reset Button

Most gas furnaces have a reset button or switch located behind a removable access panel. Here are some tips for locating it:

• Check near the burner assembly or gas valve
• Look for a button labeled "reset"
• See if there is a red or yellow button that stands out
• On older furnaces, find the reset button near the draft inducer motor
• For Amana furnaces, a reset switch is located inside the blower motor compartment
• Carrier and Bryant furnaces have a reset button on the control board

If you can't find the reset button, check your furnace manual or reach out to the manufacturer.

Accessing the Furnace Interior

To access a furnace's reset button, you'll need to remove its exterior panels:

• Turn off power to furnace at circuit breaker
• Remove any screws securing front cover panel
• Take off front panel and set aside carefully
• Inspect for any obvious signs of damage
• Locate reset button either on control board or near gas valve

Replace panels and screws when finished. Never leave furnace cover panels off while operating.

Resetting Your Gas Furnace Step-by-Step

Follow these simple steps to safely reset your gas furnace:

1. Turn off power to furnace at circuit breaker
2. Remove furnace access panel to locate reset button
3. Push red reset button in until it clicks and release
4. Replace access panel and turn circuit breaker back on
5. Adjust thermostat to call for heat
6. Listen for igniter to spark, signaling gas valve opened
7. Confirm burner ignites and blower starts pushing heat
8. Monitor furnace operation for at least one cycle

Only press the reset button once. Holding it too long or resetting repeatedly can lock out the furnace. Let the furnace fully complete its startup sequence before resetting again if needed.

What to Look and Listen for During Reset

Pay close attention right after resetting the furnace. Listen for:

• Igniter sparking sound
• Gas valve opening with a click
• Rush of gas as burner ignites
• Blower motor humming as it starts moving air

Watch the burner through the viewing window. Ensure flames ignite and look normal. The burner should stay lit for the entire heating cycle. Any issues indicate a problem needing professional diagnosis.