It's a cold winter's night, your teeth are chattering and then it happens – or rather, it doesn't happen: you turn up the heat but your home still feels cold.

Surely, something is wrong with your heating system, but you're no furnace technician. So what's going on? Most likely, your furnace isn't producing heat – or so it appears – because of:

• A malfunctioning thermostat (or one that is not actually set for heat)
• An extinguished pilot light
• A tripped or blown circuit breaker or fuse
• A dirty furnace filter
• A misaligned socket switch utility
• Blocked heat registers
• An electronic ignition problem

Now that you know the most likely causes, you can go about executing some troubleshooting tips to restore warmth to your home. To assist your best efforts, grab the owner's manual for your furnace. Then:

• Check that the thermostat is set for "heat." Laugh if you will, but it's not uncommon for a heating system service company to make a service call to repair a “malfunctioning” furnace that simply wasn't turned on in the first place. If your thermostat is turned up but still won't turn on, raise the temperature by a few degrees.
   
• Relight the pilot light if you don't see it fired up. While you're there, take two extra precautions. One, make sure that the flame is bright blue. A yellow flame signifies dirty burners, which should be professionally cleaned. And two, look for flakes of rust on the floor around your furnace. Rust flakes can block the gas flow of your furnace, which will affect its heating ability. Rust is another “cry for help” that should be answered by a professional furnace technician.
   
• Inspect the circuit breaker (or, in an older home, fuse) and replace it, if necessary.
   
• Remove the furnace filter and hold it up to a bright light or shine a flashlight behind it. (And before you do so, turn off the furnace.) If you can't see through the filter, it's time for a new one. A dirty furnace filter can cause more harm than you may think; in the worst case, a filter stuffed with dust and dirt can cause a furnace to shut down because the particles have nowhere to go. In the struggle against dirt and grime, a furnace will simply call it quits rather than wage a losing battle. Keeping your furnace filter in a healthy state is one of the easiest ways to keep your furnace running smoothly and efficiently – and to keep your home consistently warm. Expect to change your furnace filter once every several months during “high” season, though you should check it every month for good measure. It pays to keep an extra filter on hand.
   
• Flip the socket switch utility if it isn't on already. This switch is located on top of the furnace, inside of a gray box.
   
• Go room to room in your home and inspect the heat registers to ensure that they are not blocked by heavy window treatments, furniture or other objects. This is another honest oversight, easily remedied, that can spare you a service call.
   
• Call Experts In Your Home if these troubleshooting steps fail to restore warmth to your home. Your furnace might be suffering from an electronic ignition or "firing" problem.

It's also time to contact Experts In Your Home if your furnace is making strange or unusual noises – and not just when it initially fires up. It could need a cleaning or adjustment – or a good deal more – to stop your teeth from chattering once and for all.

Make sure you're properly maintaining your heating system with this free fall checklist you can download below!