Why Good Furnaces Fail

The age of your furnace does not matter

It is important to understand that no matter how old your furnace is even a couple of years old can become unsafe. Government energy guidelines have mandated HVAC manufacturers produce more efficient furnaces, one way they have achieved this is by making the metal of the heat exchanger much thinner to exhaust the heat out of the furnace faster. The problem with this is, if you have a furnace that was not properly installed or it was over sized because the installing contractor never performed a proper heat load and sizing of your house, you may not notice the problem for two years down the line and by this time you have a failed heat exchanger and cannot use the furnace.

Causes of Heat Exchanger Failure

The heat exchanger is basically a metal container separating the burning gas and the flue gases which gets vented out the chimney or through the side of your house from the indoor air that’s being heated into your home. The metal of the heat exchanger on the inside is exposed to the hot flames in the furnace and is constantly expanding and contracting as the furnace heats up and cools back down. The constant stress of this expansion and contraction of the metal will eventually cause cracks in the metal. This is better known in the industry as metal fatigue. This is similar to bending a paperclip back in until it snaps.

Down flow furnaces which are usually installed in home without basements are especially susceptible to a failed heat exchanger. The reason being the ducts are generally encased in concrete which is the floor of the home and they are generally too small and the furnace cannot properly exhaust the heat out of the furnace into the home which causes the furnace to overheat which puts undue stress on the heat exchanger. This is why it is especially important to never oversize a furnace in a down flow application.

The Furnace Blower Must Be Clean

The reason your blower does not put out the proper air flow is because of dirt that gets built up on the blades of the furnace blower and it will cut the air flow down greatly. The blower wheel and blower housing must be cleaned yearly to ensure that you are getting the proper air flow out of the furnace. The reduction in airflow will cause the furnace to operate at hotter temperatures and increase the potential of a failed heat exchanger and premature replacement of the furnace.

Is My Furnace Safe

The best way to know if your furnace is safe is to have a HVAC professional that is certified in gas combustion analyst testing, there are only a few companies certified in Cuyahoga County. To do a full furnace clean and check with gas combustion analyst takes about 1 to 1.5 hours most companies will come out and do a furnace clean and check or inspection and it only takes them only about 20 to 30 minutes when in fact in most cases they gave you a false hope that your furnace is okay because they did not properly do a gas combustion analyst and they are probably not certified and do not own the proper equipment to do this procedure.

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