What To Do When Your New Furnace Starts To Short-Cycle

Short-cycling occurs when a furnace turns on and off rapidly without completing a heating cycle. If your furnace shuts off before the home attains the pre-set thermostat temperatures, it means it is short-cycling. This problem can occur with both new and old furnaces. If you recently installed a new furnace and it is shutting off at brief intervals of less than 10 minutes, here are a few steps you can take to diagnose and fix the issue.

Look for Airflow Issues

Airflow issues in new furnaces occur due to the sizing of the ductwork. If the ducts are too small, heated air backs up and causes thermal expansion. This can cause ductwork damage and furnace short-cycling. If you have a variable-speed furnace, you can temporarily fix this problem by reducing the speed of the fan and motor. This way, air won't blast into the ducts and cause a backup. Eventually, you will have to resize the ducts to ensure proper airflow throughout the home.

Check the Position of the Thermostat

If your furnace thermostat is located in a warm spot, the surrounding temperatures will be higher than the rest of the home. Therefore, when you turn on the heat, the thermostat will record higher temperatures and signal the furnace to turn off before properly heating the home. Thus, check the position of the thermostat and ensure that it is not in the path of direct sunlight or in a room with higher ambient temperatures, such as the kitchen.

Reassess the Sizing of Your Furnace

If your furnace starts to short-cycle shortly after installation, it is probably not the right size for your home. When it comes to furnaces, bigger is not always better. If your furnace is too big for your home, it will heat the spaces too fast and shut down within a few minutes. These brief cycles stress the furnace components and cause premature wear and tear. Replace the furnace with one whose capacity matches your home's heating demand.

Check the Furnace Breaker

Even if your furnace runs on gas, it has components that require electricity to work. These parts include the blower motors, relays, pilot lights, and circuit boards. Therefore, the appliance is connected to the home's electrical wiring and distribution board. If your furnace short-cycles and stops working, check its breaker. 

A tripped breaker implies an electrical fault in the system. With new furnaces, you should look out for manufacturing defects in electrical components. Also, if the furnace is overheating due to blocked heat grates or vents, the breaker will trip to prevent damage to the blower motor. You need to resolve the electrical issue before resetting the furnace breaker.

Contact an HVAC contractor for a proper furnace diagnosis and heating repair.