Should I Get an 80% or 95% Furnace?

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When it comes time to replace your existing furnace, there are so many decisions to make. One of the most important parts of the furnace installation process is deciding what level of efficiency you need for your new system.

Whether you’re looking at a natural gas furnace or an oil furnace, it’s common to assume installing a high-efficiency furnace is the best choice. But that’s not always the case. 
When it comes to a new HVAC system, this choice isn’t just about the numbers—it’s about comfort, energy savings, upfront furnace installation cost, and long-term benefits. Adams Heating & Cooling, we break down the differences between these two options and help you decide which one is the right fit for your home and budget.

What Do 80% and 95% Efficiency Ratings Mean?

Furnace efficiency is measured by the Annual Fuel Utilization Efficiency (AFUE) rating, which indicates how effectively a natural gas furnace or oil furnace converts fuel into heat. 

  • 80% AFUE for an oil or gas furnace means it uses 80% of the gas energy it consumes and turns it to heat. The furnace eliminates the remaining 20% of energy via exhaust.
  • High-efficiency furnaces offer 90% AFUE and higher, with 95% AFUE a common percentage for a new gas-powered furnace. An 80% AFUE is considered a standard efficiency.

According to the US Environmental Protection Agency (EPA), when you make energy efficiency a priority and look for an ENERGY STAR® label on products and equipment for your Ohio home, you can reduce your energy bill by as much as 30 percent.

Differences Between 80% and 95% Efficiency Furnaces

With the 95% AFUE rating, it seems straightforward to choose this over an 80% AFUE oil or gas furnace installation—you will get more efficiency and save money over the long term on your energy bills. But this is too simplistic a perspective and not an accurate snapshot, as there are extenuating facts to consider. Take a quick look at how these two furnace options operate differently from one another in regard to energy efficiency.

The 80% AFUE Furnace

To generate energy from natural gas, an 80% gas furnace operates with open combustion. This means it extracts air from the surrounding area instead of pulling in air straight from the outdoors. It doesn’t require any type of extra venting directly to the outside air.

Pros of an 80% Furnace:

  • Lower Initial Cost: One of the biggest advantages of an 80% furnace is its affordability. It costs significantly less upfront compared to a 95% furnace, making it a good option if you’re on a tight budget.
  • Easier Installation: These furnaces have a simpler venting system, which often means lower furnace installation costs and fewer modifications to your home.
  • Reliable Performance: Despite being less efficient, 80% furnaces are reliable and can still provide ample heating for many homes.

Cons of an 80% Furnace:

  • Higher Operating Costs: An 80% furnace uses more fuel to heat your home, leading to higher monthly utility bills over time.
  • Lower Efficiency: More heat is lost through the exhaust, meaning your new furnace needs to work harder to maintain a comfortable temperature.
  • Environmental Impact: With lower efficiency comes higher emissions, which can contribute to environmental concerns.

The 95% AFUE Furnace

A 95% furnace uses sealed combustion—it pulls its needed air directly from the outdoors, generally through a PVC pipe exclusively for this purpose. It will also require an additional PVC pipe for exhaust, as it can’t work with your existing metal venting due to the condensation it creates. This option is best suited for sealed locations.

Another difference to remember is a 95% unit with its sealed combustion produces condensation. This moisture can build up and needs to go somewhere—a condensate pump and drain handle this. These components require installation and can increase furnace replacement costs if you’re switching from an 80% to a 95% AFUE furnace.

Pros of a 95% Furnace:

  • High Energy Savings: A 95% furnace is significantly more efficient, translating to lower energy bills. Over the lifespan of the furnace, these savings can make a big difference in your overall heating costs.
  • Increased Comfort: High-efficiency furnaces often feature two-stage heating and variable-speed blowers, which provide more consistent temperatures and improved humidity control.
  • Environmentally Friendly: With less wasted fuel, a 95% furnace produces fewer greenhouse gasses, making it a better choice for those concerned about their carbon footprint.

Cons of a 95% Furnace:

  • Higher Upfront Cost: The furnace installation cost for a 95% furnace is higher due to the advanced technology and additional components required for its operation.
  • Ventilation Considerations: Installing a 95% furnace often requires modifications to your home’s venting system when switching from a lower efficiency heating system.
  • Maintenance Needs: High-efficiency furnaces have more complex components that may require more frequent maintenance to keep them running at peak efficiency.

What Do These Differences Mean to You?

When choosing between an 80% AFUE furnace and a 95% AFUE furnace, homeowners must consider how these differences impact their long-term comfort, costs, and environmental impact. 

An 80% AFUE furnace offers a lower upfront cost and simpler installation, making it an appealing option for those on a tight budget. However, its open combustion design and lower efficiency result in higher operating costs, as more heat is lost during the heating process, and it consumes more fuel. 

While a 95% AFUE furnace comes with a higher initial investment and may require venting upgrades and additional maintenance, the energy savings, improved comfort, and reduced environmental impact often make it a worthwhile choice for homeowners looking to reduce long-term heating costs.

What About Electric Furnaces?

All electric furnaces are rated at 100% AFUE because they convert nearly all of the electrical energy they consume directly into heat with no combustion process or exhaust loss. Unlike gas or oil furnaces, which lose some energy through venting and flue gasses, electric furnaces use heating elements that warm the air directly without generating byproducts that need to be vented outside. 

This means that every watt of electricity used by an electric furnace is effectively turned into usable heat for your home, making them inherently 100% efficient in terms of energy conversion. 

Electric furnace installation is generally more affordable than choosing natural gas furnaces or oil furnaces, as furnace prices are lower for this type of new furnace unit. There’s also no need for a gas line; if your home doesn’t already have gas lines installed, switching to a gas furnace will require adding connections to a gas supply, which can greatly increase furnace installation costs and the time it takes to complete the furnace installation process.

However, it’s important to note that while electric furnaces have a perfect AFUE rating, their operating costs can be higher due to electricity rates, which are often more expensive than natural gas or other fuel sources.

What Else to Consider When Choosing a New Furnace

If energy efficiency is a prime factor in your new furnace decision, you should understand other gas and oil furnace specifications as well. The two most important components to consider are the different stages of heat and airflow.

Stages of Heat

There are three basic heat stages available when you buy a new furnace:

Single-Stage Furnaces

Single-stage furnaces have a basic gas valve that operates in a simple on/off manner. When the thermostat calls for heat, the gas valve opens fully, allowing maximum gas flow to the burners, and the furnace runs at 100% capacity. Once the set temperature is reached, the gas valve shuts off entirely. 

This all-or-nothing operation means that the furnace is always running at its highest setting, which can lead to frequent cycling and uneven temperature distribution. The simplicity of the single-stage gas valve makes these furnaces more affordable and reliable, but they lack the flexibility to adjust gas flow for varying heating demands.

Two-Stage Furnaces

Two-stage furnaces are equipped with a gas valve that can operate at two distinct settings: a low stage and a high stage. In most cases, the furnace runs in the lower stage, which is about 65-70% of the furnace’s maximum capacity. 

This lower stage is sufficient to maintain a consistent temperature on mild days, providing a more efficient and quieter operation. When the weather gets colder and more heat is required, the gas valve shifts to the high stage, allowing full gas flow and maximum heating output. This dual-stage operation results in better temperature control, improved comfort, and reduced energy consumption compared to a single-stage furnace.

Modulating Furnaces

Modulating furnaces use the most advanced type of gas valve, which continuously adjusts the gas flow in small increments to precisely match the heating needs of your home. The gas valve in a modulating furnace can vary the gas flow anywhere from 40% to 100% of the furnace’s capacity, depending on the current temperature requirements. This allows the furnace to maintain a steady, even heat output and avoid the temperature swings common in single-stage systems. 

The constant modulation not only maximizes comfort but also improves efficiency, as the furnace uses only the amount of gas necessary to keep your home at the desired temperature. Modulating gas valves are the most complex and require sophisticated controls, but they provide unparalleled performance and the best energy savings.

Airflow

Your furnace’s airflow also affects energy efficiency and comfort levels. When you choose a new heating system, your options will be:

Fixed-Speed Blowers

Fixed-speed blowers, also known as single-speed blowers, operate at a single, constant speed whenever the furnace is running. Once the thermostat calls for heat, the blower turns on at full speed and runs until the set temperature is reached, then shuts off completely. This on/off operation is straightforward and reliable, but it lacks flexibility and efficiency. 

Because the blower only runs at one speed, it can cause temperature swings, uneven airflow, and higher energy consumption, as it’s always running at maximum capacity regardless of the home’s specific needs. Fixed-speed blowers are typically found in single-stage furnaces and are a budget-friendly option, but they offer less precise control over comfort and air distribution.

Variable-Speed Blowers

Variable-speed blowers, on the other hand, can adjust their speed in small increments based on the demands of your home, providing precise control over airflow. Instead of just turning on or off, these blowers can ramp up or down, running at different speeds to maintain a consistent temperature and ensure optimal comfort. 

On milder days, a variable-speed blower might run at a lower speed, gently circulating air throughout your home, while on colder days, it can increase speed to distribute more heat. This adaptability leads to better temperature regulation, improved humidity control, quieter operation, and significant energy savings.

How to Decide Which Heating System Is Right for Your Home

There is no one-size-fits-all scenario for every home. Each home is unique and yours may have a completely different setup or requirements. As you see, there are varying components to deciding which furnace would best suit your lifestyle, needs, and budget.

At Adams Heating & Cooling, our HVAC experts understand the intricacies involved in making this type of investment. We can work with you to evaluate whether an 80% furnace or a 95% furnace will provide the comfort you want in your Indian Hill or Hyde Park home.

But keep this in mind. Unless you replace your standard furnace with an absolutely identical model, you will experience the benefits of higher efficiency in some capacity with whatever you choose. Small changes can reap big rewards.

We Are Your Heating Experts

If you are looking to install or replace your current furnace and want to enjoy the advantages of a high-efficiency furnace, call our Adams Heating & Cooling team or request service online today. We are here to help with all your heating and cooling needs—installation, replacement, repair, or maintenance.

Need HVAC Service?

Contact the experts at Adams Heating & Cooling.

Call us at 513-474-1600!

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