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About Gas Furnaces

Gas Furnaces

Shop Goodman gas furnaces at Same Day Supply, including 80% AFUE and 96% AFUE models for residential heating applications. Whether you're replacing an existing furnace or selecting equipment for a new installation, choosing the correct heating capacity, efficiency rating, and configuration is essential.

Our selection includes gas furnaces with different BTU capacities, blower options, and installation configurations to accommodate a variety of residential HVAC systems.

Choosing the Right Gas Furnace

Replacing a gas furnace involves more than matching the size of your existing equipment. Heating capacity, airflow requirements, fuel type, venting, and compatibility with other HVAC components all affect which model is appropriate for your home.

Understanding AFUE Ratings

Annual Fuel Utilization Efficiency (AFUE) measures how efficiently a furnace converts fuel into usable heat over a typical heating season.

An 80% AFUE furnace delivers approximately 80% of the fuel's energy as usable heat under standardized rating conditions, while a 96% AFUE furnace delivers approximately 96%.

Higher-efficiency furnaces generally use less fuel to provide the same amount of heat, but actual operating costs depend on local gas rates, heating demand, installation conditions, and equipment operation.

Furnace Size and BTU Capacity

Gas furnaces are available in different heating capacities, commonly identified by their BTU-per-hour input ratings. However, a furnace's input rating is not the same as its heating output.

Proper sizing should be based on the home's heating load rather than square footage alone. Insulation, windows, air leakage, climate, and existing ductwork all influence heating requirements.

An oversized furnace may experience short cycling, while an undersized furnace may struggle to maintain the desired indoor temperature during colder weather.

Upflow, Downflow, and Horizontal Furnaces

The installation configuration determines how air moves through the furnace and how the equipment fits into the available space.

  • Upflow furnaces draw return air from the bottom or sides and discharge heated air upward.
  • Downflow furnaces discharge heated air downward and are commonly used in certain closet or utility installations.
  • Horizontal furnaces move air through the equipment horizontally and may be installed in approved attic, crawlspace, or other applications.

Always verify the manufacturer's approved installation orientations for the specific model before purchasing.

Single-Stage and Multi-Stage Heating

Single-stage furnaces operate at one heating output when the burner is running. Two-stage furnaces can operate at a lower or higher heating rate depending on system demand and compatible controls.

Some models also include multi-speed or variable-speed blower motors. These features affect airflow control and comfort, but availability varies by furnace model.

Replacing an Existing Gas Furnace

Before ordering a replacement, confirm the furnace's model specifications, heating capacity, cabinet dimensions, airflow requirements, fuel compatibility, and venting requirements.

If the furnace operates alongside an existing air conditioner, the indoor blower and evaporator coil must also be compatible with the selected equipment.

An 80% AFUE furnace and a 96% AFUE furnace are not necessarily direct replacements for one another. Differences in venting, condensate management, and installation requirements may require additional modifications.

A qualified HVAC contractor should verify equipment selection and installation requirements before the purchase.

Shop Goodman Gas Furnaces at Same Day Supply

Explore our selection of Goodman gas furnaces and compare available models by efficiency, heating capacity, and configuration. Review individual product specifications to identify equipment that meets your installation requirements.

Looking to replace more than your furnace? Browse our HVAC equipment collection to explore additional heating and cooling options.

Same Day Supply offers online ordering and customer support to help you find the equipment you need for your next HVAC project.

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Quick Questions at a glance

Frequently Asked Questions About HVAC Equipment

What is HVAC equipment?

HVAC equipment includes the heating, ventilation, and air conditioning components that work together to keep your home comfortable year-round. Depending on your system, this may include air conditioners, heat pumps, gas furnaces, electric furnaces, air handlers, evaporator coils, packaged units, and complete split systems.

What is the difference between an air conditioner and a heat pump?

An air conditioner is designed to cool your home and works with a furnace or air handler to distribute conditioned air. A heat pump provides both heating and cooling by transferring heat between your home and the outdoors, making it an energy-efficient option in many climates.

What is a split system?

A split system separates the indoor and outdoor components of an HVAC system. The outdoor unit contains the compressor and condenser, while the indoor equipment typically includes an evaporator coil, furnace, or air handler. Split systems are the most common type of residential HVAC system.

What is a packaged HVAC unit?

A packaged unit combines all major heating and cooling components into a single outdoor cabinet. Packaged systems are commonly used when indoor installation space is limited or for certain residential and light commercial applications.

How do I choose the right HVAC system for my home?

The right system depends on your home's size, insulation, local climate, ductwork, energy efficiency goals, and budget. A qualified HVAC contractor can perform a proper load calculation to determine the correct equipment size and configuration for your home.

What size HVAC system do I need?

System size is based on more than square footage alone. Factors such as insulation, window placement, ceiling height, and regional climate all affect the heating and cooling requirements of a home. Proper sizing helps maximize comfort, efficiency, and equipment lifespan.

What do SEER2 and AFUE mean?

SEER2 (Seasonal Energy Efficiency Ratio 2) measures the cooling efficiency of air conditioners and heat pumps. Higher SEER2 ratings generally indicate greater energy efficiency. AFUE (Annual Fuel Utilization Efficiency) measures how efficiently a gas furnace converts fuel into usable heat. Higher AFUE ratings typically result in lower heating costs.

Should I replace my entire HVAC system or just one component?

In some situations, replacing a single component is appropriate. However, if your existing equipment is older or incompatible with newer efficiency standards, replacing the complete system may improve performance, reliability, and energy savings. Matching indoor and outdoor components is important for optimal operation.

How long does HVAC equipment typically last?

Most residential HVAC systems last between 10 and 20 years, depending on the equipment type, maintenance history, installation quality, and operating conditions. Routine maintenance and regular filter changes can help extend the life of your system.

Can I install HVAC equipment myself?

Most residential HVAC equipment should be installed by a licensed HVAC professional. Proper installation ensures safe operation, maximum efficiency, manufacturer warranty compliance, and adherence to local building codes.

How often should HVAC equipment be serviced?

Most manufacturers recommend professional maintenance at least once a year. Systems that provide both heating and cooling, such as heat pumps, often benefit from seasonal maintenance before both the cooling and heating seasons.

How often should I replace my air filter?

Most standard 1-inch filters should be checked monthly and replaced every 1 to 3 months, depending on household conditions. Homes with pets, allergies, or higher dust levels may require more frequent filter changes to maintain proper airflow and indoor air quality.

Does higher efficiency equipment save money?


Higher efficiency HVAC equipment typically consumes less energy, which can reduce monthly utility costs. While high-efficiency systems may have a higher upfront cost, many homeowners recover that investment over time through lower energy bills and improved comfort.

Do you sell complete HVAC systems?

Yes. Depending on the equipment category, complete systems may include matched indoor and outdoor components designed to work together. Individual replacement components, including furnaces, air conditioners, heat pumps, air handlers, and evaporator coils, are also available.