With the first freeze, people may be putting their furnaces to use.
"Right now we're just cleaning off the flame sensor," said Jeff Miller, a technician at CW Suter. "It's one of the main things that causes issues in the winter."
Heating and cooling companies like CW Suter respond to service calls to make sure things are working properly.
"First thing we need to do is make sure the furnace actually comes on for the cold weather this year and when someone calls us for a service agreement we'll go out and we'll do a 20 point check on their furnace," said John Baker, president of CW Suter.
Among those points are safety items to check for.
"We make sure that the heat exchanger is not cracked," said Baker. "If the heat exchanger is cracked, it can cause carbon monoxide poisoning. So we make sure that that heat exchanger is in proper working order."
"Usually what I'll do once I inspect it, I'll turn the furnace on and then we'll just have to make sure the flames aren't rolling out or anything," said Miller. "That's a good sign there's an issue with air getting in to the heat exchanger."
They also check the humidifier.
"And change the humidifier pad to make sure the humidifier's going to properly humidify the house to make sure the house doesn't feel dry," said Baker.
And one of the main things to look out for is the filter.
"The biggest fault I don't think people do is they don't change their filter often enough," said Baker.
When the filter is changed, the unit will move more efficiently, which means more warmth and comfort for the cold season.