In a gas furnace, the blower will continue to run if the fan switch on the thermostat is set to any setting other than auto. The blower on a furnace will also continue to run if its filter is extremely clogged.Know More
When the furnace's thermostat is set to auto, the fan will only run until the space that is being heated or cooled reaches the preset temperature. Settings such as low, medium or high cause the fan to run continuously regardless of the temperature that is reached in the space.
A clogged filter may cause the furnace's blower to run continuously because it can damage the furnace's limit switch. The limit switch is designed to detect the temperature inside of the furnace. It automatically shuts off the fire in the furnace if the temperature becomes too high until the furnace has the chance to reach a safe temperature.
A clogged filter also restricts the air flow inside the furnace. This causes the safety switch to remain open, causing the fan to run continuously. The fan will not stop until the safety switch closes. In this case, a fan that continues to run is a sign that the furnace has overheated.Learn more about Heating & Cooling
While there are several small maintenance and repair tasks a homeowner can perform on a gas furnace, HomeTips recommends that for more complicated repairs a professional HVAC repair person is consulted. Some repairs that are do-it-yourself include fixing a noisy furnace or ductwork, relighting the pilot light and replacing a blower pulley.Full Answer >
Maintain a gas furnace properly by checking and cleaning the furnace's filters, vents, blower, thermostat, ducts and fan regularly. Replacing these parts as needed is also a part of proper gas furnace maintenance.Full Answer >
BTU, which stands for British Thermal Unit, is a unit measurement often used to list how much energy a gas furnace or other heating unit produces. One BTU is the amount of energy required to heat one pound of water one degree Fahrenheit.Full Answer >
A gas furnace should be replaced when the furnace begins making weird noises, reaches a certain age or displays decreased efficiency and after the burner flame turns yellow. Generally, a gas furnace should be replaced when the furnace costs over $500 to repair or is more than 15 years old.Full Answer >