When your furnace is blowing air but the air is cold, it usually means the blower fan is working but the heating element or gas burners have failed to ignite.
If the blower is on but warm air isn't coming through, here are a few possible causes: Faulty ignitor or pilot light: Your furnace may be trying to heat, but if the ignitor fails, no flame means no warmth. Thermostat issues: Sometimes, it's as simple as incorrect settings or a thermostat that needs replacement.
Typically, a furnace should cycle 3 to 8 times per hour, running for about 10 to 15 minutes each time. If it's cycling more frequently (short cycling) or running for 20+ minutes straight regularly, something's not right.
If your furnace fan won't shut off, first check your wall thermostat. Make sure the fan is set to "AUTO" instead of "ON". If it’s already on auto, turn the thermostat to "OFF" or set it to a temperature significantly lower than the current room temperature.
Reset the Furnace
Turn the thermostat to "OFF." Locate the power switch on the furnace (often looks like a light switch) or the circuit breaker. Turn it off for 30 seconds, then flip it back on. Turn the thermostat back to "HEAT."
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.
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.
5 Warning Signs It's Time for Furnace Replacement
Running your furnace fan constantly can improve indoor air quality and balance temperatures, but it does increase energy usage. For most households, it is best to use the "Auto" setting during summer to prevent humidity issues, and switch to "ON" or "Circulate" during winter to keep air fresh and rooms evenly heated.
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.
How many hours should my heating be on a day? For most modern homes, Patrick Garner, Gas Safe Engineer at Heatable, tells us that having your heating on for 4-6 hours a day, "split between short boosts at the times you actually need warmth", is a good general rule.
No, 68°F is not generally considered cold for a house in winter. In fact, experts at the U.S. Department of Energy recommend 68°F as the ideal, energy-efficient temperature for the winter months while you are awake.
On average, furnaces should kick on and turn off anywhere from three to eight times per hour. However, if your furnace turns on and off more frequently, don't assume the furnace is short cycling just yet.
The Furnace Won't Ignite: This is the most common and most telling sign. If the gas valve doesn't open, the ignition sequence simply can't begin. Intermittent Heating or Sudden Shutdowns: These unpredictable cycles often point to weak solenoid coils or unstable electrical connections.
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.
If the blower is on but warm air isn't coming through, here are a few possible causes: Faulty ignitor or pilot light: Your furnace may be trying to heat, but if the ignitor fails, no flame means no warmth. Thermostat issues: Sometimes, it's as simple as incorrect settings or a thermostat that needs replacement.
If your furnace fan won't shut off, first check your wall thermostat. Make sure the fan is set to "AUTO" instead of "ON". If it’s already on auto, turn the thermostat to "OFF" or set it to a temperature significantly lower than the current room temperature.
If you'd like to calculate your ideal HVAC fan runtime, here's a simple formula: Measure the square footage of your home. Divide the square footage by 2. This number represents the number of minutes your HVAC fan should run per hour.
The $5,000 rule is a guideline to help homeowners decide whether to repair or replace their HVAC system. You multiply the age of your unit by the cost of the needed repair. If that number exceeds $5,000, replacing your HVAC system is often more cost-effective.
A standard residential furnace lasts 15 to 20 years. However, the exact lifespan varies based on the type of system and how well it is maintained.
Short cycling
This is one of the most common furnace problems, and it can stress important furnace components such as the blower motor, limit switch, or flame sensor. There are several potential causes of short cycling, including some that are related to your furnace's built-in safety systems.
You know it is time to replace your furnace when it is over 15 to 20 years old, requires increasingly expensive repairs, or struggles to maintain consistent heating. Waiting for a total, freezing-weather breakdown leaves you with higher costs and limited options, so being proactive is crucial.
If it doesn't start at all, you can press the button one more time. But, if you press the reset button and your furnace goes on and turns off again, don't press the button again. Continuing to press the reset button can damage your system. Doing so will pump more oil into the furnace and worsen any existing issues.
Heating Schedules. Keep to a steady heating schedule over winter to keep a home consistently cozy. HVAC technician Josh shares, 'On average, in winter weather, most furnaces or boilers will cycle on and off for eight to 12 hours per day. That's assuming daytime temps around 35-45°F (1 to 7°C) and nights in the 20s.
Although comfort is personal and can vary, a generally comfortable temperature for a house is often set between 68 and 72 degrees Fahrenheit. This range is considered ideal for most people to feel comfortable indoors.