How does a thermocouple affect a furnace's ability to produce heat?

What happens when a furnace has a defective thermocouple?

1) The furnace will not turn on
2) The furnace will not produce heat
3) The furnace will produce excessive heat
4) The furnace will produce a burning smell

Answer:

The most likely issue when a furnace has a defective thermocouple is that the furnace will not produce heat.

A thermocouple plays a crucial role in the operation of a furnace. When the furnace has a defective thermocouple, it will directly impact the furnace's ability to produce heat. A thermocouple is a safety device that senses the temperature of the pilot flame in a furnace.

When the pilot flame is lit, the thermocouple generates a small electrical voltage. This voltage keeps the gas valve open, allowing the furnace to produce heat. However, if the thermocouple is defective and fails to generate the necessary voltage, the gas valve will close, preventing gas from reaching the burner, and consequently, the furnace will not produce heat.

Therefore, if you encounter a situation where your furnace is not producing heat, one of the first things to check is the functionality of the thermocouple. Replacing a defective thermocouple can help restore your furnace's ability to effectively generate heat and keep your home warm and comfortable.