Everything You Should Know About Heat Pumps
What Can Fail On Your Furnace's Control Board?
Jessica Jimenez
Like most modern appliances, your furnace needs an electronic control board to manage its many functions. Although most furnaces use relatively simple control hardware, this component is still critical to its operation. The board signals your furnace to begin heating and runs through the bevy of checks necessary to keep it operating reliably and safely.
Unfortunately, control boards aren't immune to failure. These electronic components can occasionally cause issues with your heating system, especially if exposed to excessive heat or soot due to another problem with the furnace. Recognizing how and why control boards suffer these failures can help you deal with them more quickly and easily.
Understanding Your Control Board's Role
The control board acts as a central hub for your furnace, ultimately switching various components on and off as needed. The board also receives signals from your thermostats and supplies power to them along a 24V line. Despite having so many connections, furnace control boards are reasonably straightforward compared to the electronic circuit boards found in more sophisticated appliances.
In general, the board must handle a few tasks to provide you with heat. Once a thermostat requests heating, the board checks that each safety switch is in the appropriate position. If these checks pass, it moves on to activating the draft inducer, engaging the igniters, and ultimately turning on the blower. The board will also make additional safety checks at each step, shutting the sequence down if needed.
Since the board handles every step of your furnace's operation, a non-functional control board can cause various unusual symptoms or simply prevent your furnace from lighting at all.
Recognizing How and Why Control Boards Fail
Control boards are solid-state electronics, making them relatively robust. In theory, these components should last for a substantial amount of time since they don't face any form of mechanical wear. The control board also isn't typically exposed to significant heating and cooling cycles, one of the primary causes of failure in electronic components.
Despite this, failures in control boards can and do occur. Issues can occur due to poor solder connections, arcing over relays and switches, or even electrical inconsistencies in your home's wiring. For example, lightning strikes can potentially damage the circuit boards in your furnace, creating overvoltage situations that can burn out contacts and damage the board.
Since control board failures aren't widespread, HVAC techs will usually check for other problems before condemning the board. If they do suspect a board failure, they'll look for physical signs of damage in addition to checking the board's operation using a multimeter. For instance, overvoltage situations or arcing switches often create visible burning and pitting on the board.
If your board has failed, you'll usually need to replace it. Control board replacement is a complex job involving a relatively expensive part, so this is a task best left to professionals.
For more information on heating services, contact an HVAC contractor in your area.
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