furnace won't start

No Heat? Why Your Furnace Won’t Start

Reasons Your Furnace Might Not Start

A properly functioning furnace helps you live comfortably and safely through the cold winter months in Idaho. On a bitter cold night, your heating system isn’t a luxury—it’s a necessity. When your furnace fails to start, panic can quickly set in. 

To keep you safe and sane in the event of a non-starting furnace, let’s review how to respond if you find yourself in this situation. 

What to Inspect if Your Furnace Won’t Start

If your furnace won’t start, here are a few possible causes you can check for right away on your own. 

Thermostat and Furnace Connection

There might be a connection error between the thermostat and the furnace. One might not be responding appropriately to the other. 

Thermostats can be quite sensitive. If they become dirty or they’re accidentally bumped, calibration issues can occur. If you’re viewing an error code on the thermostat, check the manual to see what problem the code indicates. 

It’s possible that you’ve simply forgotten to turn the thermostat on, or that someone else in the house turned it off or changed a setting. Or, a power outage could have reset the thermostat. So, double-check the status of the thermostat before attempting any structural troubleshooting. 

Dirty Filter

Furnace filters can become dirty and clogged. A dirty filter restricts efficient airflow from the furnace. This makes it difficult for the furnace to circulate heated air throughout your home, and can also negatively impact your indoor air quality. A clogged filter can even prevent the furnace from starting at all. 

When your furnace filter is dirty, replace it with a new one. Filters should be checked every month and changed whenever they get dirty. Remember to turn the furnace completely off before inspecting or replacing your filter. Call an HVAC professional if you’re unsure about how to proceed. 

Pilot Light (For Gas Furnaces) 

The furnace’s igniter could be malfunctioning. If you believe that to be the case, turn off the furnace and turn off the gas. Then, contact a professional. 

If you know how to locate and clean the igniter, this could potentially be a DIY fix. However, to ensure that the igniter isn’t damaged, the best choice for most homeowners is to bring in an HVAC professional. 

Smell for Gas 

A faint gas smell as your furnace cycles on is normal. However, a frequent, strong, or distributed smell of gas is a serious concern. This could indicate a dangerous gas leak. 

If you notice a troubling gas odor after turning on your furnace, head outside right away and contact an HVAC professional. Tell them that you’re experiencing a gas leak from a broken furnace and that it’s an emergency. 

Disrupted Gas Line

Make sure that the gas supply to the furnace is open. Also keep in mind that the gas system requires electricity. So, a power outage or a tripped breaker can disconnect your furnace from the power supply it requires in order to function. 

If any mechanical problems or damages are disrupting gas flow, you’ll need to bring in a professional for inspection and repair. 

Old or Broken Furnace

Furnaces have a typical lifespan of 10-15 years, or maybe up to 20 years with a bit of luck and proper maintenance. Once your furnace hits the 15-year mark, you can expect the need for regular maintenance and, eventually, replacement. 

Furnace Still Won’t Start? Contact a Professional Today

If you’re feeling stumped as to why your furnace isn’t starting, the best option is to contact a professional HVAC service technician. 

For Idaho homeowners in the Treasure Valley region, Advanced Heating and Cooling is here to help keep your home warm and cozy this winter. We offer furnace sales, installation, and maintenance services across the entire Boise metro area. 

We service all major furnace brands and our team has the expertise to quickly diagnose and address any HVAC concern. 

This winter, keep your home warm and your mind at ease. To get started, schedule an appointment with us anytime. 

For immediate assistance, we offer 24/7 emergency service. Call us at 208-336-COOL if you’re in the middle of an HVAC emergency. 


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