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Discover the Secret to Lower Heating Bills!

Updated: Jun 26

Lower heating bill

When it comes to keeping homes warm during Washington's cold winters, high efficiency furnaces are a game-changer. The experts at Cascade Electric are here to explain how these modern systems work compared to older models and what homeowners need to know about their electrical demands.

Traditional Furnaces vs. High Efficiency Furnaces

Traditional Furnaces

Older, conventional furnaces typically have an Annual Fuel Utilization Efficiency (AFUE) rating between 56% and 70%. This means a significant portion of the fuel they consume is wasted. These systems generally feature:

  • Single-Stage Gas Valves: Operate at full capacity until the set temperature is reached, then shut off completely, resulting in inconsistent heating and higher energy use.

  • Single-Speed Blowers: Run at one speed regardless of the heating demand, leading to uneven temperatures and inefficiency.

High Efficiency Furnaces

High efficiency furnaces, on the other hand, boast AFUE ratings between 90% and 98.5%. Key components that set them apart include:

  • Two-Stage or Modulating Gas Valves: Allow the furnace to adjust its output to match the heating demand, providing more consistent and efficient heating.

  • Variable-Speed Blowers: Adjust the airflow based on the heating needs, improving comfort and reducing energy consumption.

  • Secondary Heat Exchangers: Extract additional heat from the combustion gases, significantly reducing waste.

  • Sealed Combustion Chambers: Draw air from outside for combustion, enhancing safety and efficiency by avoiding drafts.

How High Efficiency Furnaces Work

High efficiency furnaces are designed to extract maximum heat from the fuel they burn. Here’s a look at their operation:

  • Ignition: When the thermostat calls for heat, the furnace ignites the gas burner using an electronic ignition system, which is more reliable and efficient than older pilot lights.

  • Primary Heat Exchanger: The gas burner heats the primary heat exchanger. Air blown over this exchanger absorbs the heat and is then circulated through the home’s ductwork.

  • Secondary Heat Exchanger: Combustion gases pass through a secondary heat exchanger, where more heat is extracted, cooling the gases to the point where water vapor condenses.

  • Condensate Removal: The condensed water is drained out of the furnace. This is why high efficiency furnaces are sometimes called "condensing furnaces."

  • Exhaust: Finally, the cool exhaust gases are vented outside through a PVC pipe, unlike older furnaces that require a metal flue due to higher exhaust temperatures.

Electrical Demands and Circuit Requirements

Older furnaces use simple, single-speed blower motors that run on standard 120-volt circuits, with steady but inefficient power consumption. High efficiency furnaces, however, use advanced electronics and variable-speed motors, which can draw more power intermittently, particularly when starting up.

Dedicated Circuit Requirements

According to Washington State electrical codes, and as recommended by Cascade Electric, high efficiency furnaces generally require a dedicated electrical circuit. Here’s why:

  • Prevent Overloading: A dedicated circuit ensures the furnace has a stable power supply without competing with other appliances. This is especially important for high efficiency models with variable-speed motors that can have higher startup power demands.

  • Safety: The advanced electronic controls in high efficiency furnaces are sensitive to voltage fluctuations. A dedicated circuit helps prevent electrical issues that could damage these components or cause malfunctions.

  • Code Compliance: The National Electrical Code (NEC), which Washington State follows, typically requires that central heating systems have their own dedicated circuit to enhance safety and reliability.

High efficiency furnaces offer substantial improvements over older models, providing better performance, greater comfort, and significant energy savings. However, their advanced technology and variable-speed components mean they have different electrical demands. Ensuring the furnace has a dedicated circuit, as per Washington State regulations, is crucial for preventing electrical issues and ensuring smooth operation.

If you're considering upgrading to a high efficiency furnace, consult with Cascade Electric. Their professional electricians can ensure your home's electrical system is up to the task, allowing you to enjoy the benefits of advanced heating technology while keeping your home warm and your energy bills low.


(509) 656-4211



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