Quick answers: resetting your furnace
How do I reset my furnace?
Find the furnace power switch, flip it off, wait about 10 seconds, then flip it back on. Give the furnace a few minutes to run through its startup sequence. If nothing happens, check your electrical panel for a tripped breaker labeled furnace, HVAC, or heating, and flip it fully off before switching it back on.
Where is the furnace shut-off switch located?
It looks like an ordinary light switch and is usually mounted on the side of the furnace, on a wall a few feet away, or at the top of the basement stairs. In many older Chester County homes it sits at the stairwell, which is why it gets bumped off by accident.
How long should I wait before turning the furnace back on?
About 10 seconds is enough for the control board to fully power down. After you switch it back on, allow a few minutes before you decide whether it worked, since most furnaces run a safety and startup sequence before the burners light.
Is it safe to reset a furnace yourself?
Yes. Flipping the power switch or resetting a breaker is homeowner-safe and requires no tools and no panel removal. Stop and call a professional if you smell gas or burning, if the breaker trips again, or if the furnace lights and immediately shuts back down.
Why won't my furnace turn on after a reset?
A reset only clears temporary faults like a system lockout or a thermostat communication glitch. If the furnace still won't start, something mechanical or electrical is likely failing, and it needs a professional diagnosis.
Last Revised: 7/23/26
Your furnace was fine yesterday. But this morning the house is cold, the vents are quiet, and you’re standing in the basement wondering how bad this is going to be.
Here’s the good news: a furnace that’s stopped working isn’t always a major issue. A surprising number of no-heat calls turn out to be a power switch someone flipped by accident or a furnace that locked itself out and just needs to be restarted. Resetting your furnace takes about five minutes, costs nothing, and is completely safe to do yourself.
Below are the exact steps, the same ones we walk through in the video on this page.
How Do I Reset My Furnace?
Work through these in order. There’s a chance you won’t have to go beyond step three.
- Find the furnace power switch. It looks just like a regular light switch. Check the side of the furnace itself, the wall a few feet away, or at the top of the basement stairs (often with a red wall plate).
- Confirm the switch is in the ‘on’ position. This switch gets accidentally switched off more often than you’d think. It can happen during cleaning, by children, or when someone’s moving storage boxes around. If it was off, flip it on and wait a few minutes.
Pro Tip: Place a piece of heavy-duty tape over your furnace power switch in the ‘on’ position to prevent it from accidentally being switched off.
- If the furnace still isn’t responding, reset it. Turn the switch off, wait about 10 seconds, then turn it back on.
- Give the furnace a few minutes. It’ll take more than a few seconds to respond. Modern furnaces run through a safety and startup sequence before the burners light, so you may hear the inducer motor before you feel any warm air.
- Can’t find a switch, or not noticing anything happen? Check your electrical panel. Look for a breaker labeled furnace, HVAC, or heating. A tripped breaker often sits slightly out of line with the others, or is sitting in a middle position rather than fully on.
- Reset the breaker completely. Flip it fully off first, then back on. Half-flipping a tripped breaker is the most common reason a breaker reset ‘doesn’t work.’
- Check the thermostat while you’re at it. Make sure it’s set to heat, the temperature is set above the current room temperature, and the batteries aren’t dead. A thermostat with dead batteries can look exactly like a furnace that’s failed.
If the furnace fires up and runs a full cycle, you’re all set. Nothing further is needed.
Where Is the Furnace Shut-Off Switch Located?
Almost every furnace has a dedicated power switch nearby. It’s a standard toggle switch, typically located in one of three places:
- Mounted directly on the side or top of the furnace cabinet
- On a nearby wall or joist, within a few feet of the unit
- At the top of the basement stairs, next to the stairwell light switch
You’d be surprised by how many homeowners call a professional HVAC company to inspect their furnace, when their furnace switch at the top of the basement stairs is accidentally switched off. In a lot of the older homes we service around Downingtown, West Chester, and the surrounding Chester County townships, the furnace switch and the basement light switch sit side by side and look identical.
What a Furnace Reset Can and Can’t Fix
Cutting power clears the furnace’s control board, which is genuinely useful for a specific set of problems.
A reset often resolves: a temporary system lockout after several failed ignition attempts, a thermostat communication error, or a control board glitch following a brief power flicker, something we see plenty of during windy weather in southeastern Pennsylvania.
A reset won’t fix: a failed ignitor, a dirty flame sensor, a cracked heat exchanger, a failed blower motor, or a gas supply problem. Those are mechanical failures. Power cycling may temporarily mask them, but the furnace will run into the same issue usually within a day or two.
If you’re resetting your furnace repeatedly to keep the heat on, you haven’t found the real solution. That’s the system telling you something is wearing out. Our guide to the furnace parts most likely to fail covers what’s usually behind repeated problems.
When to Stop and Call a Professional
Skip the reset and call for service if any of these apply to you:
- You smell gas. Leave the house first, then call your gas utility from outside. Don’t flip any switches on your way out.
- You smell something burning. Shut the furnace off at the switch and call for service.
- The breaker trips again after you reset it. A repeat trip means an electrical fault, and resetting it over and over is a fire risk.
- The furnace starts and immediately shuts back off. This short-cycling pattern usually points to a safety sensor doing its job to prevent any hazards.
- You hear unusual noises like banging, screeching, or grinding.
- The furnace still won’t start after you’ve reset the power and the breaker.
If your system is over 15 years old and this isn’t the first no-heat call this season, it may be worth reading through whether to repair or replace your furnace before you spend money on another repair.
Still No Heat? We’re Here When You Need Us
You shouldn’t have to guess whether your family is going to be warm tonight. For more than 75 years, families across Chester, Delaware, Montgomery, and Berks counties have called us when the heat goes out. You get a straight answer, a warm house, and no pressure to make a decision on the spot. Take the next step towards ending your furnace worries and get back to the things that really matter.
