Before You Embark on Heater Replacement, Know What You’re Looking For

Published on: September 25, 2013

When you’re considering a heater replacement, the decisions you make will affect your comfort and energy bills for years to come. Here in the Southeast, we have several options that will provide efficient heating during the colder months when home heating is necessary.


Our options include heat pumps and combustion forced-air furnaces. Each kind has its own benefits:

  • Heat pumps are often chosen for this region because they work well in climates where subfreezing temperatures are infrequent. Heat pumps work by moving heat from one place to another. Air-source heat pumps, the most common variety, extract heat energy from the air. In the winter, the air-source heat pump extracts heat energy from the outdoor air and brings it inside. In the summer, the cycle reverses and it takes the heat from your home and exhausts it outdoors. Meanwhile, geothermal heat pumps extract heat energy from underground (or underwater) for heating, and then deposit it back in the ground for cooling.When your air conditioner needs to be replaced and you need a heater replacement as well, a heat pump might be your best option, since it provides both efficient cooling and heating, and the technology performs well in our region. They’re easy to operate, and provide safe heating since they pose no risk of carbon monoxide (CO) poisoning.
  • Forced-air gas furnaces use propane, fuel oil or natural gas to create heat. As household air entering the air handler blows over the heat exchanger, it warms and the fan distributes the heated air throughout your home by sending it through your home’s ductwork. A gas furnace will deliver warm air regardless of the outdoor temperature.If your central air conditioner is less than 10 years old, runs efficiently and you have a natural gas line on your property, this type of system works well as a heater replacement. However, if you have to run gas to your property, or set up a propane or fuel oil tank, this may not be your best option. And while natural gas prices are currently quite low, there’s no guarantee they’re going to stay that way.

Efficiency Ratings

All HVAC equipment carries energy-efficiency ratings that tell consumers how well the system converts fuel or electricity into usable heat. Furnaces that use natural gas have AFUE (annual fuel utilization efficiency) ratings that indicate how much of the fuel is turned into heat for your home instead of going up the chimney. Heat pumps carry HSPF (heating season performance factor) ratings, which indicate how efficiently they use electricity for heating.

The AFUE is expressed as a percentage. The federal government’s minimum efficiency level for central forced-air furnaces is AFUE 78 percent, which means that 22 percent of the fuel goes up the smokestack. Systems are available that have AFUE ratings close to 100 percent, which means that they convert almost all the fuel they use for heating. The minimum HSPF for heat pumps stands at 7.7 and goes as high as 10 for the most efficient systems.

If you’re considering a heater replacement through the end of 2013, you could take advantage of federal tax credits by installing a high-efficiency heat pump or gas furnace. The minimum AFUE for a gas furnace that qualifies for the 25C tax credit program is 95 percent, while the required HSPF for heat pumps starts at 8.0, depending on the type of heat pump you install. The credits allow you to deduct 10 percent of the cost for a maximum credit of $150 for high-efficiency furnaces and $300 for qualifying heat pumps.


Both heat pumps and combustion furnaces have options and upgrades that improve comfort and increase energy efficiency.

Heat pumps

  • Scroll compressor. A heat pump that uses a scroll compressor instead of the usual piston compressor will bring in 10- to 15-degree (Fahrenheit) warmer air. Such a compressor raises the HSPF and generally lasts longer than a piston compressor.
  • Variable-speed motor in the air handler. This type of motor uses far less electricity than a single-speed motor, is quieter and adapts its speed to your temperature needs. The slower and more continuous running speed helps circulate the air throughout your home, warming spaces in your home evenly.

Another option for our climate is a dual-fuel heat pump that uses a supplemental gas furnace that kicks on only when temperatures fall to freezing or lower (or when you switch it manually). The system automatically switches to the furnace, so you avoid having to use the electric supplemental heating coil in the heat pump. The backup electrical heating element consumes about three times the electricity that the heat pump does to deliver heat.

Another way to avoid using the supplemental heating element is to install an upgraded thermostat that employs adaptive heat recovery technology that turns the heating element off. These thermostats will override the programmed settings when the heat pump senses that temperatures are colder.

The thermostat will turn the heat pump on more frequently to gradually raise the temperature. Without such a thermostat, the heat pump might have to use the heating element to heat your home quickly in the morning, increasing energy consumption.

Gas furnaces

One of the best upgrades for a gas furnace for our region is variable-heat output. Such a system varies the amount of gas used based on the heating needs of your home. It won’t use the full amount when your heating load is lower. This device will raise the AFUE of the furnace. Combining this option with a variable-speed blower will give you a high-efficiency heater replacement that doesn’t use as much fuel and electricity.

The most efficient furnaces employ two heat exchangers and are called condensing furnaces. They extract the heat in the water vapor that the gas creates by sending the vapor through the second heat exchanger. The AFUE of these systems can be 95 percent or higher, depending on other upgraded technologies used inside them.

Condensing furnaces have sealed combustion chambers that increase winter safety, since they use outside air in the burner chamber. The furnace vents the combustion gases directly outside. Any of these upgrades to gas furnaces will increase the price, but depending on where you live, you may recover the extra expense over time, since fuel consumption will be lower. Your HVAC technician should advise you on the efficiency level for your particular climate. The pros generally advise homeowners in the Deep South that a high-priced condensing furnace probably isn’t necessary, since the heating demands are so low.

Either system 

Depending on the size of your home, the number of stories in the house and your usage patterns, a zoning system could help you lower your heating bills. If your bedrooms are all upstairs, you have a livable basement, or you don’t use a space continually, you can put it on its own zone and operate that zone only when you need it. Each zone has its own thermostat and the ductwork has dampers inside that open and close based on the need for heating.


As you work with HVAC contractors for your heater replacement, make sure that the contractor sizes the new system properly for your home. Going by the size of the existing equipment could result in choosing a system that’s the wrong size. A heating system that’s too large will run in short cycles, which drives up energy costs and decreases indoor comfort. The air in your home won’t have a chance to mix, making some places in your home cooler than others. Systems that are too small may not provide the warmth you need during the coldest weather and the system will run continually.

Contractors use software called Manual J to find the right size heating system for your home. It takes into account these factors:

  • Cubic footage you need to heat;
  • Energy efficiency of windows;
  • Insulation levels in the attic and walls;
  • Air infiltration rates;
  • Preferred indoor temperatures;
  • Household size and occupant ages;
  • The amount of heat you generate indoors; and
  • Landscaping factors.

Once the data is run through Manual J, you’ll know what you can do to make your home more energy efficient, possibly helping you lower the size of the heater replacement you need. Sealing air leaks and adding insulation to the attic are cost-effective ways to reduce the size heating system you need. Since furnace or heat pump pricing is directly tied to size, being able to install a smaller system will save money immediately and for years ahead.


The contractor needs to conduct a thorough inspection of your ductwork system to verify that it’s adequately sized and configured for you get the most efficiency from the heating system. Manual D software assists the contractor in this calculation.

Your ducts need to be inspected to find leaks or other problems before the heater replacement is complete. Loose or leaking ducts reduce the heating efficiency regardless of the type heating system. If you use any vented gas appliances in your home, including a furnace, these leaks could draw CO into your home.

If you’re looking for a heater replacement, getting professional assistance will make the task much easier. We at AC Southeast® can help you find a trusted expert for this complicated task. We provide top-notch HVAC services for homeowners in South Carolina, Georgia, Florida, Mississippi and Alabama, and look forward to helping you find the best heating option for your home.