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Serving The Greater
Coeur D’Alene & Spokane Area

Serving The Greater Coeur D’Alene & Spokane Area


ACI Northwest Blog

Here’s How Your Furnace Really Works

Many people don’t realize that furnaces have undergone quite a few changes over the last few decades. Because some people hold on to their furnaces for much longer than is recommended, they often believe that you must light the pilot light before making use of a furnace for the winter. While this may be true of furnaces and wall units that are decades old, modern-day furnaces do not have this kind of pilot light, which means they are much more efficient.

The Pilot Light

Today, there are two different types of ignition systems used to start up a furnace: intermittent pilots and hot surface ignition.

  • Intermittent Pilot: A high-voltage spark lights up the pilot when the thermostat calls for heat, and the furnace turns on when the flame sensor detects the flame.
  • Hot Surface Ignition: A small metal piece like a lightbulb filament heats up when electricity runs through it, hot enough to ignite the burners.

The Blower Fan and Heat Exchanger

The burners move heat through the heat exchanger, and the combustion gases (such as carbon monoxide) vent through the other end of the heat exchanger, into a flue that safely vents the gases away from the home.

The blower fan may take a moment to turn on, as the air plenum must reach a certain temperature first. Air heats up as it moves into the plenum and past the heat exchanger, and then it enters the ducts.

Air Ducts

Typical duct systems are balanced so that the temperature in the home stays relatively even. If you have multiple thermostats in the home, you likely have a zone control system in your ductwork. Dampers open and close to let more air in or block airflow into a room so that you can keep different zones at differing temperatures.

ACI Northwest is here to help you with your home comfort needs or concerns. Please do not hesitate to contact us for helpful advice or furnace services in Spokane Valley.

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