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What’s the Most Efficient Way to Heat Your Home?

Published on: October 18, 2014
An HVAC tech checking his gauges | AC Southeast

In the Southeast, where we don’t have to worry about months of freezing temperatures, the most efficient way to heat your home isn’t always obvious. While that can make finding a heating system a little more confusing, it also means you have more flexibility in choosing exactly the right system for your needs. Taking a little time to learn the basics of several systems will help you make the best choice.

The Parts of an Heating System

Heating systems consist of three main parts. Each one has its own efficiency considerations.

  • Heat source – This part of the system is where the heat comes from. Most furnaces and boilers burn fuel to create heat. A heat pump, on the other hand, absorbs heat from the outdoor air. This is the greatest consideration when choosing the most efficient way to heat your home.
  • Heat distribution – This is how heat gets from the source to individual rooms. Most forced-air systems, such as furnaces and heat pumps, use ducts and registers to carry and deliver warm air to your rooms. Ductless heat pumps, however, use indoor air handlers. Boilers use metal radiators or another form of radiant heating such as radiant flooring.
  • Control system – In most residential heating systems, this is the thermostat. Installing a programmable thermostat can save you money by making it easier to maintain comfortable, energy-saving temperatures in your home.

Furnaces: The Familiar Option for Reliable Heating

Furnaces come in two basic types: fuel-burning and electric. Fuel-burning models burn natural gas, oil or propane to create heat that warms the air. The warm air is then distributed throughout your home via your duct system. Electric furnaces use electric heating coils to warm the air.

Give the relative cost of common heating fuels versus electricity, fuel-burning furnaces are typically cheaper to run. That means one of these furnaces could be the most efficient way to heat your home.

Besides efficiency, there are a few other benefits to heating with a furnace.

  • Easy upgrade – If you already have a furnace and want a more efficient way to heat, upgrading to a higher-efficiency furnace is almost certainly your most cost-effective option. Unless you also need to replace the air conditioner, it may not make financial sense to install a heat pump to do the job of your furnace and A/C. Switching to a boiler would mean installing radiators, a major expense if you currently use ducts.
  • Inexpensive – Furnaces tend to be cheaper to purchase and install than boilers, which have more complex installation requirements.
  • Long life span – A modern furnace’s life span is between 15 to 20 years. That’s a least five years longer than you could expect a heat pump to last. Chances are you’ll decide to upgrade to a more modern furnace model before your existing one finally breaks down and must be replaced.
  • Easy maintenance – Because furnaces are more common than boilers, it’s often easier to find a technician who’s knowledgeable about furnace maintenance. Furnaces require only one annual tune-up. Heat pumps, which run year-round, do best with two tune-ups per year.

Furnace Efficiency

In order to decide whether or not a furnace is the most efficient way to heat your home, you’ll need to know a little something about furnace efficiency ratings. A furnace’s energy efficiency is indicated by its annual fuel utilization efficiency (AFUE). This number tells you what percent of fuel the system consumes goes toward producing heat for your home. In a system with an AFUE of 97, 97 percent of the fuel is burned for heat while 3 percent is lost with the exhaust gases or in some other way.   

Today’s high-efficiency furnaces offer AFUEs between 90 and 98.5, although models on the high end are less common.

To meet Energy Star requirements for the South, only a 90 percent AFUE is necessary. That’s the minimum if you’re really aiming for efficient heating. For the greatest cost savings, look for a somewhat higher efficiency.

In our area, however, the highest efficiency furnaces are generally not good investments. We rarely need the amount of heating that makes the slight increase in fuel savings worth the higher equipment purchase price.

For help determining the efficiency range that’s optimal for your climate and needs, talk with a heating and cooling professional.

Regardless of the model you choose, there are a few efficiency-boosting features to look for in your next furnace. These include sealed combustion, condensing technology and a variable-speed fan motor.

Heat Pumps: Efficient Heating and Cooling

In the mild climate of the Southeast, there’s a good chance a heat pump will end up being the most efficient way to heat your home. Heat pumps are highly efficient at warming because, although they run on electricity, they move heat rather than produce it. This allows heat pumps to create around three times more energy in heat than they use in electricity.

These systems can both heat and cool through the use of a reversing valve that reverses the flow of the refrigerant they contain. In cooling mode, they work just like an air conditioner. In heating mode, they use refrigerant to absorb warmth from the outdoor air and transfer that warmth into your home.

Although heat pumps are less efficient in temperatures below 40 degrees, when the electric auxiliary heat kicks on, many of today’s systems remain highly efficient even in cold weather. We rarely see the kind of low temperatures that would impair a heat pump’s efficiency.

Heat Pump Efficiency

Because they don’t burn fuel, heat pumps are given different efficiency ratings than furnaces. To judge a heat pump’s overall efficiency, pay attention to both HSPF and SEER.

  • Heating season performance factor (HSPF) – This number tells you how efficiently the heat pump heats. It’s calculated by dividing the amount of electrical energy consumed into the amount of heating produced. For a more efficient system, look for higher HSPFs. Although 8.2 HSPF is sufficient to meet Energy Star requirements, systems with HSPFs of 12 or higher are also on the market. 
     
  • Seasonal energy efficiency ratio (SEER) – This number tells you about the heat pump’s cooling efficiency, so it’s something you’ll want to pay attention to given our area’s hot summers. As with HSPF, SEER is also calculated as a ratio and a higher SEER means a more efficient system. Earning Energy Star standing requires a SEER of at least 14.5. Look around, though, and you’ll find SEER 20 or higher systems out there, too.

Keep in mind, though, that because heat pumps run all year, they typically last only 10 to 15 years.

Ductless Heating Offers Convenience and Efficiency

Even if you decide a heat pump would ultimately be the most efficient way to heat your home, you may find installation prohibitively expensive if your home doesn’t already have air ducts.

Ductless systems give you the best of both worlds: a high-efficiency system with no need for ducts. These systems are based on heat pumps, but instead of using ductwork, they use air handlers mounted on the wall or ceiling, or stood on the floor. One heat pump can operate up to four indoor air handlers, which is plenty for the average-sized home.

Rather than the construction work required to install ducts, installing a ductless system requires just a 3-inch hole in the wall for the conduit line between the outdoor and indoor units.

These systems are less expensive to operate than traditional heating systems for two main reasons:

  • High efficiencies – Ductless heat pumps offer some of the highest heat pump efficiency around. For example, the Toshiba Carrier residential ductless highwall heat pump system achieves an HSPF of 10 and a SEER of 23.
  • No duct losses – If you opt to install a furnace and duct system, your system will suffer from inefficiencies a ductless system could avoid. Installing ducts after construction typically results in sub-optimal ductwork that doesn’t carry air efficiently. A ductless system, on the other hand, would deliver all the warm air it produces straight to your rooms.

If you’d like some help finding the most efficient way to heat your home, try our Find a Contractor service at AirConditioningSouthEast.com We’ll help you locate a knowledgeable, reliable heating and cooling contractor near you.