A broken heat anticipator in the thermostat is a classic failure that causes nothing to happen when the heat is turned on. However, "nothing happening" can stem from a few other key failures.
If your thermostat is on but no heat is coming out, the quickest fixes are to replace the thermostat batteries, reset the furnace’s power switch, or check your home's circuit breaker.
A failing thermostat can compromise your comfort and spike your utility bills. Watch for these top warning signs:
If the screen is non-responsive, you can try rebooting the thermostat at the circuit breaker.
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".
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.
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.
The reset button's location depends on your thermostat type. For older models, it is usually a recessed button on the circuit board (often behind the faceplate) or a dedicated button on the front or side. For modern smart thermostats, you typically reset the device through the digital menu.
If your engine is overheating quickly, the cabin heater blows cold air after warm-up, and your upper radiator hose is burning hot while the lower hose remains completely cool, your thermostat is likely stuck closed. This prevents hot coolant from circulating to the radiator to drop the temperature.
Pushing the reset button on a thermostat clears errors and restores communication with your HVAC unit. However, depending on the type of reset, it will usually erase all custom schedules, temperature settings, and Wi-Fi configurations.
A failing thermostat usually shows clear signs: the HVAC or engine behaves erratically, the screen is blank, or the temperature in your home/car does not match the settings.
A plumber isn't usually needed for thermostat replacement unless your thermostat directly controls a water-based heating system, such as underfloor heating or a boiler with complex plumbing connections. Even then, an electrician is typically the right professional to handle the wiring.
Average Lifespan of a Thermostat
With a straightforward design and basic scheduling features, they are reliable workhorses that can last 10 to 15 years with proper care. Routine programming updates and occasional recalibrations go a long way toward keeping them accurate and extending their usefulness.
How can you tell if a thermostat is bad?
The average life expectancy of a thermostat is about ten years. That doesn't necessarily mean that your thermostat will stop working as soon as you've had it for ten years. However, ten years is a long time in the world of technology.
First, check your thermostat for any operational lights and then check your boiler control panel for faults. If you have a boiler fault, check your manual to learn more about what to do. You may have to call a heating engineer. If the thermostat or boiler is non-responsive, then you may have a power issue.
Fixing a stuck thermostat generally costs between $𝟐𝟎𝟎 and $𝟕𝟓𝟎 for a car, or $𝟏𝟓𝟎 and $𝟓𝟎𝟎 for a home HVAC system. A stuck thermostat cannot usually be repaired and must be fully replaced along with a system flush or fresh coolant.
If your car's thermostat is stuck closed, your heater will blow hot air initially, but the engine will rapidly overheat, which can cause severe damage. It is highly recommended to pull over and address the issue immediately.
One of the most common thermostat-related problems that homeowners run into involves incorrect temperature readings. A thermostat that displays incorrect temperature readings can cause significant heating issues. There are several potential causes of an incorrect temperature reading, starting with improper placement.
Resetting your thermostat clears temporary glitches and restores factory defaults. To reset your device quickly, choose the method below that matches your thermostat type:
Get your heating running again with a few quick checks. First, ensure the mode is explicitly set to “Heat” and the target temperature is at least 3 to 5 degrees above your current room temperature. Next, check if your unit uses batteries.
A standard thermostat reset takes just 30 seconds to 5 minutes, depending on the model.
To reset your furnace, start by turning off the circuit breaker and furnace power, wait about 30 seconds to a minute, then turn the power back on. If your furnace uses gas, you may also need to turn off the gas for a few minutes before turning it back 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.
Below, we've explained the top signs your furnace needs repairs or replacement.