We’ve all heard the horrifying news story about the family that just barely escaped alive, or perhaps worse the family that died while asleep, there lives ended by a silent killer. The silent killer is Carbon Monoxide. If you don’t change or maintain your furnace filter as recommended by the manufacturer you may be putting your family in danger. Your furnace filter is meant to remove dust from air as it passes thru the furnace. The longer your furnace filter is in use the dirtier it gets. This increased loading of the filter with allergens creates a resistance to air movement through the filter and restricts air circulation.
Gas furnaces, like all heating and air conditioning units, are engineered to have a certain amount of air movement at all times to work properly. This air movement is measured in CFM. This equipment utilizes a heat exchanger that has the heat source, fire, within and the air passes over the heat exchanger on the outside. As the air flows around the heat exchanger it picks up the heat from the flame inside.
In order to get top efficiency from these heating systems, the walls of the heat
exchanger are made as thin as possible though not so thin that they can not tolerate the heat they’re subject to during normal operation.
A filter that remains in the system so long that it starts to adversely effect air circulation can be problematic. As the quantity of air flowing around the heat exchanger
declines, the operating temperature of the heat exchanger increases. This is when a heat exchanger can fail because it is operating above design conditions. The warmer the heat exchanger becomes the more it expands when heated, and contracts as it cools during the off cycle. This expanding and contracting can become excessiveexcessive and cause the walls of the heat exchanger to warp or crack. A cracked heat exchanger may allow CO to escape to the air in your home.
The good news is that correctly manufactured furnaces have High Limit safety switches that eliminate extream heating of the heat exchanger. These limit safety devices sense the temperature at or close to the heat exchanger and if the temperature reaches a predetermined set point, the equipment will turn off either till manually reset or till the limit switch senses that the temp
A furnace can function a long time on an auto reset limit switch without anybody even knowing. This means that the furnace is operating at the boundaries of its design capacities. Today, most safety switches must be reset by hand. They are designed this way so the furnace will not operate until it is serviced and the problem fixed.
Don’t depend on these safety switches to protect you from disaster. These are mechanical components which can and do fail to operate properly occasionally . So reduce your risk by changing your furnace filter often. It is always best to follow manufacturers reccomendations.
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