After a high of 69 degrees Tuesday, winter weather has returned Wednesday. Many people are turning their heating units back on, especially with lows forecasted in the 20s for Wednesday night.

Typically, there is not a problem with fluctuating between air conditioning and heat, but there are a few things to look out for with your heater.

If a heating unit has been off for a long time, then build-up develops in the drain, burners, or electric heating element.

"A heat pump has its auxiliary heat come on, you'll smell a kind of burning smell. It's not necessarily dangerous, but it is something that you typically notice once the heat has been off for a while," said Kevin Horne, co-owner of Action Air. 

So, if you smell a little burning when you switch from air conditioning to heat, you do not need to be concerned.

If smells are stronger or you notice sound or temperature differences, it's better to have the unit checked early than wait until the bottom drops out. Waiting means a minor problem may become a more expensive problem.

"You're thinking, well, this thing is making a weird noise or it has a weird smell coming out of the duct. Call us. You need to get it checked out because it could theoretically be something that could harm you if it is a gas unit especially," Horned explained.

Horne recommends that everyone with a gas appliance has a carbon monoxide detector, which can be purchased at hardware stores. They save lives.

"If the heat exchanger rusts or cracks, carbon monoxide will leak out of that into the air stream and go into the air, and it does not take much to make you sick. It doesn't take much to kill you," stated Horne.

Additionally, if you see frost on your outside heat pump in the next few days, don't be concerned. A layer between a quarter and a half inch thick is normal before defrost begins. If it continues to build up, then there is a problem.

Finally, a helpful cost savings tip is to find your comfortable temperature inside and leave the thermostat set there. Turning your thermostat up and down costs more money, especially if you have a heat pump because the more expensive supplemental electric heat kicks on with temperature changes over 2 degrees.