Tips on Buying a Gas Furnace

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When considering replacing your old furnace, a gas furnace is an excellent alternative to their electronic counterparts due to their energy-efficiency. Heating with gas has been long known for it being the fuel of choice since it is the most economical.


All new natural gas furnaces available today are high-efficiency, with an Annual Fuel Utilization Efficiency (AFUE) of 90 percent or higher. However, homeowners need to consider a few things first when trying to determine the type and size of unit that would suit your home and needs.

One of the first things to consider is the size and square footage of your home as well as the layout and number of floors. This will influence the size and BTU of the furnace you need to keep your home warm and comfortable. You will also want to consider an Energy Star model because furnaces with Energy Star certification will meet certain efficiency standards. Most may qualify for government rebates.

Types of Gas Furnaces

There are primarily three types of gas furnace systems – Single-stage furnace, Two-stage furnace, and Modulating furnace.


  • This type is considered to be the standard in the market, and it comes with heating systems featuring gas valves that can either be in the open (letting the gas flow at a high rate) or closed position. Similar to a vehicle accelerator pedal having only two settings – stop or go full blast, this is not the most energy efficient option.  Many single-stage furnaces have 80% annual fuel utilization efficiency (AFUE), which is significantly better than their predecessors, but not the best available option out there in terms of energy savings.


  • Furnaces with two-stage heating systems offer greater flexibility as one can adjust the flow of gas according to heat requirement.  The fuel control valve has two open positions instead of one, hence the name; partially open position and a fully open position, chosen based on the reading measured by the thermostat. You can expect a two-stage furnace to provide AFUE close to 90%.


  • Gas furnaces with modulating valves adjust the heating output from 35% to 100% of furnace capacity. They continuously regulate the amount of burned fuel with the most enhanced accuracy. With a modulating furnace, the fuel output is controlled by as much as 1% increase or decrease depending on your home’s heating needs. The best in quality modulating gas furnaces also offer maximum energy efficiency, in addition to better air distribution and better air flow.


There are also a few features that might influence your decision making:

Variable Speed Blower Motors

  • A blower in the furnace controls air circulation. A variable speed blower motor has multiple fan blower speeds and automatically adjusts to meet heating and cooling demands. The benefits of a variable speed blower motor is that it uses approximately 75% or 60% less electricity, has a longer lifespan than conventional blower motors, and is quieter than standard blowers.

Energy-Saving Electronic Ignition

  • Today’s gas furnaces are much more energy-efficient. Electronic ignitions have replaced the pilot light found on older furnaces. The burner is ignited only when the thermostat calls for heat.

Zoned Heating

  • A zoned heating and cooling system breaks your home into different areas or “zones,” each controlled separately by a thermostat. Zoning your home allows for several benefits including elimination of hot and cold spots and individual control of different rooms’ temperatures.

Best Choice

While the cost of living has gone up for the past 10-years, natural gas rates have remained low. Natural gas is clean, safe, and reliable. Best of all, abundant supply makes it the most affordable fuel for your energy needs and the best value for your energy dollar.