Nik Rajkovic / news@whmi.com

Sub-freezing temperatures are in the forecast for much of the WHMI listening area this week -- with overnight lows down in the teens.

Nicole Bramlett with Bramlett Heating & Cooling, says routine furnace maintenance goes a long way this time of year.

"It's not too late to do it. We are still doing them weekly for customers. One of the most important things to do is to maintain the efficiency of the unit by getting it checked yearly. That will also reduce the risk of mid-season breakdowns."

Bramlett says swapping out your furnace filter and thermostat batteries also helps keeps the warm air flowing.

"Not changing you filter can lead to furnace overheating, and it will also reduce the amount of clean air in your home," she says.

"Another good thing to do is to replace the batteries in your thermostat and to give it a test. You can raise the furnace a few degrees. Does the furnace turn on? Is it blowing out warm air? Also, make sure your registers and your vents are clean and unobstructed."

Anyone hearing odd noises from their furnace, or cool air coming from the vents, is urged to contact their repair technician. Ignoring it could lead to costly repairs, such as frozen pipes.