A furnace overheats if its internal
temperatures exceed a safe limit. The overheating damage can suffer major
component failure if you don't solve the issue. Below are some of the common
reasons a furnace might overheat.
Airflow Restrictions
Proper air circulation is necessary
to heat the house and minimize heat accumulation in the furnace. Without
adequate air circulation, heat can build up in and overwhelm the furnace.
Discover some typical causes of airflow restrictions:
- A dirty air filter that starves
the furnace of air
- An incorrect filter that
behaves as a dirty one
- Duct blockage that prevents
airflow to and from different rooms
- Register blockage that prevents
airflow from and to different rooms
Restricted airflow can also force
the furnace to overwork to maintain the desired temperature. The constant
operation can also overheat the furnace.
Aging
A good furnace should last you
between 15 to 20 years. The furnace has a finite lifespan
since its components, such as the motor, experience wear and tear whenever the
furnace runs. The furnace materials also deteriorate with time. As the furnace
ages, friction increases in its moving parts, and its heating output reduces.
The wear and tear can cause the furnace to overheat and overwork.
Limit Switch Failure
The fan limit switch is a
multifunctional part of your furnace. The switch determines on and off points
for the furnace's cycles. The switch also turns down the furnace if it begins
to overheat. The switch has a temperature sensor for these functions. If the
switch's sensor or other components fail, the furnace will continue to run at
dangerous temperatures.
Thermostat Issues
The thermostat senses the house
temperature and sends the signals to the mainboard, which controls the heating
functions. That might not be the case if the thermostat:
- Doesn't have power (due to
disconnected wires or dead batteries)
- Does not have the correct
temperature setting
- Is in the wrong location where
external heat affects it
In such cases, the furnace will
continue to run even if the house is already warm enough. The lengthy run times
will cause the furnace to overheat.
Dirty Components
Various parts of the furnace,
including the motor, gather dirt every day. Over time, the dirt accumulation
grows and reduces heat dissipation from the furnace. The accumulated dirt also
increases friction on moving parts of the furnace. These two issues can
overheat the furnace if you don't clean it regularly.
Short Cycling
The furnace doesn't run all the time
— the furnace starts when the temperature drops and switches off if the
temperature matches the thermostat setting. The off cycles allow the furnace to
cool and reduce the wear and tear. Unfortunately, the furnace might not cool
enough if the cycles are too short. Typical causes of short cycling include:
- Improper sizing: A furnace that is too large
for your house will heat up the house too fast, turn off, and start again
as the house cools.
- Blocked flue: Flue gases are hot, so they
will overheat the furnace if something blocks their escape.
- Air leaks: Your house will cool down
rapidly if it has substantial air leaks. Rapid cooling will shorten the
furnace's off cycles.
Your furnace will short cycle if it
heats the house too fast, if the house cools down too fast, or if a malfunction
(such as an electrical issue) keeps shortening the furnace's run time.
Many issues can cause furnace overheating, and
you need a diagnosis to unearth the problem.
Contact A-1 Finchum Heating & Cooling if your
furnace keeps overheating or if the overheating has already caused damage. We
will diagnose the problem and fix it so that your house can be comfortable
again.
