A furnace not kicking on for heat is often caused by a tripped circuit breaker, a clogged air filter, incorrect thermostat settings, or a dirty flame sensor. Most issues can be safely diagnosed and resolved at home with a few simple steps.
To get your furnace to kick on, first verify your thermostat is set to "Heat" and raised at least 5 degrees above room temperature. Next, check that the furnace power switch (usually resembling a standard light switch on or near the unit) is toggled "ON".
A frozen pipes furnace failure can cause major problems inside your home. Ice builds up fast in unheated spaces, and when frozen water expands, it can burst pipes wide open. That kind of mess is the last thing anyone wants during a winter heating outage.
6 Ways to Creatively Heat Your House If Your Furnace Broke
To reset your furnace safely, lower the thermostat and turn off the power at the furnace switch or circuit breaker. Wait 2 to 5 minutes, then turn the power back on. If your furnace has an internal reset button (usually red or yellow), press and hold it for 30 seconds.
All furnaces are equipped with a reset button. They are generally red or yellow and are located inside the blower compartment. The reset button is a safety feature that will shut down the furnace when a problem is detected, often a hot or overheating furnace, before it trips the circuit breaker.
Resetting can recalibrate the temperature sensor. Failure to Turn On HVAC System: A thermostat reset reboots its system and attempts to restart normal functioning. This resolves problems where it fails to turn on your AC, heat, or fan.
To diagnose a furnace issue, start by checking the thermostat settings and ensuring it's set to "heat" and at the right temperature. Inspect the air filter for clogs and replace if dirty. Ensure the furnace switch and circuit breaker are on.
The heat exchanger is often considered the most costly part of a furnace to repair or replace. It is a critical component that transfers heat from the combustion process to the air that circulates throughout your home. Over time, heat exchangers can crack due to the constant heating and cooling cycles they undergo.
You may feel this is the easiest and most harmless step, but the reset method is not the same for all types of systems, and it is not right to reset your system frequently. If you face the same problem more than once or twice, do not reset your system every time. It will damage your furnace.
Even with the heat on, these vulnerable areas may not get enough warmth to prevent freezing. How do I know if my pipes froze or burst? If no water comes out when you turn on a faucet, the pipe is likely frozen. If you see water stains, hear running water, or notice water where it shouldn't be, a pipe may have burst.
Focus on Safety and Immediate Comfort
Your first priority should always be the safety of you and your family. If the temperature inside your home starts to fall, gather everyone into one or two rooms to retain warmth. Make sure to close doors to unused spaces, add extra blankets, and dress in warm layers.
It's such a simple thing, leaving a single faucet dripping, but it can prevent so many complications later on. How much value does one dripping faucet have? A lot, if it keeps your home's water pipes from bursting during frigid weather.
When a furnace stops working unexpectedly, it's usually due to a tripped breaker, a dead thermostat, or a blocked safety switch. Before paying for an expensive service call, you can safely troubleshoot the issue yourself.
To determine if your furnace fuse is blown, turn off the power to the unit, remove the automotive-style fuse from the control board, and inspect it for a broken metal filament or dark burn marks. Alternatively, use a multimeter to check for electrical continuity.
Troubleshooting a furnace that is not responding to a thermostat can often be done safely by checking basic settings before attempting any electrical bypasses. Bypassing a thermostat, often referred to as "jumping," involves working with live electrical terminals and should only be performed by a qualified HVAC technician to avoid the risk of electric shock, blowing a transformer fuse, or causing a fire hazard.
Your furnace’s reset button is typically a small, bright red or yellow button located either inside the blower compartment, near the burner assembly, or directly on the motor housing.
What fails first on a furnace? The most common early failures are the furnace ignitor or flame sensor, as they experience regular wear and tear and are critical to starting the heating cycle.
5 Warning Signs It's Time for Furnace Replacement
Most furnace issues stem from a few common culprits. The easiest to check yourself are clogged air filters and thermostat errors, which usually cause the system to blow cold air, run inefficiently, or cycle on and off constantly. Other frequent problems include dirty flame sensors or failing blower motors.
Homeowners insurance may cover the cost to repair or replace your furnace or boiler if it's damaged or destroyed by a covered peril. Covered perils as defined by your policy typically include events such as: Lightning. Fire.
A furnace typically lasts between 15 and 20 years. However, the exact lifespan varies based on the type of unit and how well it is maintained.
Subtle Signs Your Furnace Is Starting to Break Down
Here's what to watch for: Increased Utility Bill: A sudden spike in your utility bill can signal inefficiency in your furnace, often a sign it's working harder than usual. Strange Noises: Unusual sounds, like banging or whistling, might indicate internal issues.
Signs of a failing control board include the furnace not starting, the blower fan running nonstop, flashing error codes on the unit, and the system not responding to the thermostat.
If your furnace fan is running but blowing cold air, the system is likely trapped in a safety lockout. The most common culprits are a clogged air filter, a dirty flame sensor, a tripped high-limit switch, or improper thermostat settings.