Photo of Joe Kloke
Joseph Kloke; Instructor of Heating, Ventilation and Air Conditioning

As a friend of mine moved into a hotel for a few days this fall while her furnace and flue pipes were replaced, I thought to myself how easily this could have been avoided.

I know that people think a heating system cleaning and check is nothing more than a filter change and cleaning the flame sensor but I assure you that when it is done by a competent technician it is much more involved than that. At one time in my career, I made a list of tasks that should be done or checked during a fall service and came up with a 44 point list.

I know no one wants to spend extra money, but there probably isn’t much else in your home that can be as deadly as a poorly working furnace. A reputable technician will do a lot of work to make sure you are safe, and make sure you don’t have preventable problems during the winter. Through regular inspection of your system, you should be able to avoid breakdown and be warned years before your furnace reaches the end of its life.

The most dangerous consideration of a furnace is safety. Carbon monoxide poisoning is a silent killer and gas leaks can cause fires and explosions!

A furnace has a series of tubes that the fire and combustion gases are directed through on their way out of the house. Air from the house is directed across these tubes and heat is transferred from the hot gases and fire into the air of the home. This is called the heat exchanger. The tubes are sealed to keep carbon monoxide and other dangerous byproducts of combustion out of the air we live in and breathe. From there we carefully direct these combustion gases outside through flue pipes to a location that is safe. These systems and parts need regular inspections to keep us safe, as they all will wear out and need repair at some time through their life.

Eventually over the life of a furnace after the heat exchanger has heated up and cooled off thousands of times, the heat exchanger will develop cracks when the metal fatigues. That’s where the problem comes in. These cracks allow these combustion gases to leak into living space where we breathe the carbon monoxide and it builds up in our bodies. As part of a proper clean and check, a technician will partially disassemble the furnace to check this heat exchanger for hidden cracks as well as corrosion and make sure that there are no signs of incomplete combustion. This is all to keep your family and home healthy, warm and safe.

It is important to have a quality carbon monoxide and gas detector installed in your house. I want to warn you, though, that some cheaper detectors will not pick up low levels of carbon monoxide, and most will not alert until the level is dangerous. Even at low levels, carbon monoxide can build up in your body and affect your health. As the weather gets colder we will have our furnaces running more hours per day, which means more carbon monoxide can accumulate in houses and bodies.

So what does carbon monoxide poisoning feel like? In large enough concentrations carbon monoxide poisoning feels like having the flu. You may have symptoms like headaches, dizziness, weakness, nausea, vomiting, chest pain, confusion and blurred vision. And if enough carbon monoxide builds up in your system you will pass out. The worst danger is when people reach these levels while sleeping because they may not wake up to get relief. If you find that you feel better when you go to work or are getting headaches or feel dizzy during your time at home you should investigate this more and call a technician.

It is also important to make sure that the gas piping is installed properly. Flexible connectors are not rated for this type of installation and may cause restrictions or even crack.  Have your piping system inspected for proper size and support of the gas piping, as well as for leaks. Gas piping can loosen up over time as vibrations from the furnaces are transferred into the connections. Technicians will also make sure that the gas pressure is set correctly and check and adjust heat rise. Both of these will contribute to a long furnace life.

As the weather drops to the coldest days of the year most of our furnaces will run most hours of the day to keep our houses warm. And those are not the days to have your furnace repaired or replaced. Regular inspections of heating systems can keep that from happening and—most importantly—keep you and your family safe.

Waubonsee Community College offers education and training in heating, ventilation and air conditioning services. Visit to learn more about these options and career opportunities in this field.

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