Furnaces can suffer damage even while sitting idle during the warmer months. Cracks form in the heat exchanger or firebox, and pests build their nests in your air ducts. When winter comes, and the temperatures outside are unbearably cold, you'll be glad that you took the steps to make sure that your furnace was in good operating condition. Here are four things you need to do in order to ensure that your furnace is ready to keep your home comfortably warm during the winter.

1. Test the Batteries in Your Carbon Monoxide Alarms

While your furnace was sitting idle during the warmer months, it may have developed a crack in its heat exchanger. A cracked heat exchanger can cause your furnace to emit carbon monoxide into your home. Carbon monoxide poisoning can be deadly, so it's important to test your carbon monoxide detectors before you need to turn your furnace on during the winter. Detectors have a test button on them that causes them to chirp — if a detector doesn't make any noise, replace its battery before you use your furnace.

If you don't have any carbon monoxide detectors in your home, install them before using your furnace this winter. At a minimum, you need a detector on each floor of your home in a centralized location along with a detector in every bedroom in your home. Carbon monoxide detectors are inexpensive, easy to install and helps to ensure safe operation of your furnace. 

2. Take Your Furnace for a Test Run

When the weather turns freezing, you don't want to be caught unaware with a furnace that doesn't turn on. You should test your furnace before winter hits by letting it run for an hour. While this may make your home uncomfortably hot, it lets you know that your furnace will be operational when you really need it.

3. Check for a Lingering Burning Smell While the Furnace Operates

It's normal for a furnace to emit a slight burning smell when it hasn't been used in a while — dust that has settled in the furnace will begin to burn up. However, you should call a professional HVAC contractor if the smell continues for more than twenty minutes after you've turned the furnace on. It could be a sign that you have a crack in your furnace's firebox.

4. Make Sure Your Furnace Heats Every Room of Your Home

Make sure the furnace is adequately heating every room of your home. Open all of your vents and make sure they're unobstructed. If there's no warm air reaching one or more vents, it could be a sign that you have an obstruction in your air ducts. You'll need to call a heating contractor to examine your ducts and clear them of any obstructions.

If you're unsatisfied with the performance of your furnace during its test run, call a heating professional and schedule an appointment. Your furnace will be examined for any problems that may be causing it to do a poor job of heating your home. Poor performance could also mean that it's time to replace your aging furnace. By testing your furnace before freezing weather hits, you'll be able to remedy the situation before you truly need to use it, which can save you from having to make an emergency call to a heating contractor.