What Should You Know About Your HVAC Control Board?
Most homeowners are familiar with a few critical parts of their furnace, such as the electric ignition or the air filter. These crucial elements help your furnace to operate correctly and efficiently, but they are simple components that are incapable of regulating the operation of your home's furnace on their own. Instead, they rely on the control board to act as the brains of the unit.
Although any modern furnace should include this element, many people may be unfamiliar with its function or the signs of failure. Electronic components can be intimidating, but learning a bit about your control board can help you understand when something has gone wrong. Keep reading to discover how this lone circuit board helps keep you warm and toasty as summer transitions into fall and winter.
Understanding the Many Roles of the Control Board
Your control board serves several purposes in your furnace and air handler unit. One of its primary functions is to receive input from your thermostat and furnace sensors, make decisions based on that data, and then distribute messages to other components in the system. Without a properly functioning control board, elements such as your igniter may never receive instructions to turn on.
The control board is more than just a dumb relay, however. Furnace manufacturers design modern control boards to monitor sensor input for signs of trouble. This role helps your furnace to operate safely. For example, the control board can use data from the flame sensor to prevent your gas valve from remaining open if the igniter has failed.
Additionally, the control board can perform a similar function to the ECU in your car. Many control boards can store error codes when a sensor reports erroneous data or sensor data indicates a potential fault. In these cases, you can usually retrieve the error code by checking a flashing LED on the control board against a list of possible errors found in the furnace's user manual.
Surprisingly, your control board is even responsible for powering your home's thermostats. A transformer inside your furnace housing converts your home's 120V line voltage to 24V. This voltage then supplies the control board, which distributes that power to each thermostat in your house.
Recognizing Common Control Board Faults
Given its importance to the proper functioning of your HVAC system, a faulty control board can lead to many issues. If your control board is not receiving power or it fails to properly output power, then your furnace may not function at all. A faulty control board can also lead to issues at your thermostats.
In some cases, problems that seem to originate with the control board are power faults. If the furnace's transformer fails, then it may not output the correct voltage to the transformer. Without 24V power at the control board, your furnace will not function. Likewise, your furnace includes a fuse to protect the igniter and blower motor. If this fuse blows, then your igniter and blower will not operate.
When the control board itself fails, it's typically due to an aging component on the board, such as a transistor or relay. Although these components can withstand relatively high temperatures, years of heating and cooling cycles can wear them out. Issues with your home's electrical wiring or even a clogged filter can sometimes result in excessive wear on control board components.
Repairing a Faulty Control Board
If you can track a problem with your control board down to a faulty transformer or fuse, then you can usually replace these individual components to get your furnace working again. When the failure is on the control board, replacing the whole board is typically the only option. Since you will be dealing with delicate wires and household voltage, you should trust this work to an HVAC professional.
Comfort Solutions can help you solve any problem with your home's HVAC system, including complicated control board failures. Give us a call to schedule an appointment today.
