Furnaces are the most common residential heating system in the U.S. In fact, almost 35 million homes in America are heated by natural gas furnace systems accounting for about 30% or more of an average home electric bill while pumping up to 4 tons of carbon dioxide into the atmosphere every month.** Most people buy their first furnace without even realizing it when they buy a house with their furnace already installed. Most people also put the same amount of thought into purchasing the second furnace as the first but you can really save money and energy with careful research and the purchase of the right energy efficient furnace.

Steps to buying a new home furnace

The first step, as is with any heating and cooling system, is to make you’re your furnace is properly sized. To do this, have your HVAC contractor do a load calculation which takes into account the size of your house, the insulation value of your windows, the amount of insulation in your walls and roof, and a host of other criteria to determine the appropriate furnace capacity. If your furnace is too big, it will cost you substantially more to operate than a correctly sized furnace. This is because oversized furnaces typically cycle on and off more often than correctly sized furnaces, and cycling on and off is more expensive than running at steady state. 

Second look for a furnace unit with the correct Annual Fuel Utilization Efficiency or AFUE. The AFUE measures the amount of fuel converted to space heat in proportion to the amount of fuel entering the furnace. As a result, a furnace with an AFUE between 85% and 90% is typically about 15% more efficient than non-energy efficient models.* Please note that high efficiency furnaces typically cost more than average and low- efficiency furnaces but they typically cost less to operate on a per month basis as they use less fuel to generate the same amount of heat. So over the life of the furnace, a high efficiency furnace will actually save you money even though the up front cost is higher.

If your current central air conditioner is more than 10-12 years old, it's time to upgrade and if you select an energy efficient variety, the amount you'll save in energy bills will more than likely exceed the cost of the new unit.

If you want to replace your central air conditioner, first look for models that have a high seasonal efficiency rating (SEER). Energy Star qualified central air conditioners have mush higher SEER ratings than standard models which makes them about 14% more efficient. 

Also remember that a bigger unit is not necessarily a better unit. A central air conditioner that is too powerful costs more to buy and cycles on and off more frequently, reducing its efficiency. Frequent cycling makes indoor temperatures fluctuate more and results in a less comfortable environment. So make sure that your new central air system is properly sized for your home. 

As with room air conditioners, to determine how much cooling power in British Thermal Units, or BTU’s, you’ll need…simply multiply the square footage of the interior of your home by 10 and then add 4,000…that’s the BTU number you’ll need to find the right central air conditioner. Or in the alternative, ask your HVAC contractor to do a load calculation which takes into account the size of your house, the insulation value of your windows, the amount of insulation in your walls and roof, and a host of other criteria to determine the appropriate furnace capacity.

When buying a large home appliance such as a new central air conditioner, it is important to get a quality installation by selecting the right contractor or installer.

Traditional Water Tank

Most people own a giant water tank that is continually heating and storing water (either by electricity or a gas furnace) for use throughout the day.  With traditional tank heaters, you want to make sure that your water heater fits your needs in terms of capacity. To determine the capacity or volume (measured in gallons) of your existing water heater, just look at the nameplate or the yellow Energy Guide sticker.  Another good idea is to look at the first-hour rating to see how much hot water the model can deliver during a busy hour. As a result, you may want to purchase a water heater with a high first-hour rating if you use hot water at small but intense times of the day.


Tankless Water Heaters

Tankless water heaters heat water directly without the use of a storage tank and as a result, they avoid the standby heat losses associated with storage water heaters.  When a hot water tap is turned on, cold water travels through a pipe into the unit. With an electric tankless water heater an electric element heats the water while a gas-fired tankless water heater a gas burner heats the water.  As a result, tankless water heaters deliver a constant supply of hot water and will heat water only when you need it. They are rated by how many gallons of hot water they produce per minute (GPM). As a result, if you find yourself using the shower, dishwasher, and washer/dryer at once on a regular basis, you will need a larger GPM.  On average, a shower requires 2.5 GPM, washer 3.3 GPM, a kitchen sink 2.2 GPM and a dishwasher 1.3 GPM.



Also, remember to check your state energy office or local utility offer rebates and trade-ins of older models to encourage the purchase of energy-efficient units. To learn more about what rebates are available in your state for energy efficient water heaters, please visit the DSIRE website 

Whether you end up replacing your heating and cooling systems or just want to make due with what you have, follow these simple tips to maximize the efficiency of your home and all of your heating and cooling systems:



1. Check the filters on all of your heating and cooling devices every month, especially during winter and summer when they are in heavy use. If the filter looks dirty after a month, change it. Dirty filters will slow down or even block air flow through the filter making the system work harder and wasting energy. A clean filter will also prevent dust and dirt from building up in the system preventing maintenance or the system simply breaking.



2. Have a contractor or professional technician regularly inspect and tune up your heating and cooling systems to make sure they are working properly. Simple maintenance will ensure that your systems are working properly and for a long time.



3. Install a programmable thermostat. For a longer discussion on programmable thermostats and how to use them properly, check out our section “Programmable Thermostats” above.



4. Inspect your home to make sure that you have proper insulation and that there are no leaks in any of your heating or cooling ducts.  For example, ducts that move air to-and-from a forced air furnace, central air conditioner, or heat pump are often big energy wasters and by sealing and insulating ducts can improve the efficiency of your heating and cooling system by as much as 20 percent.* For a long discussion on insulation and making sure that your home is leak free, check out our sections on Home Insulation and Home Energy Audits.



5. For all of your cooling systems, make sure the system has the proper amount of refrigerant installed. Your cooling system will operate more efficiently and for longer if it is properly charged with the correct refrigerant.



6. Finally, before you purchase any new home equipment, check with your local HVAC Contractor (Heating Ventilation and Air Conditioning) to see if there any federal, state or local utility rebates for buying energy efficient products so you can save more money. 

*source: www.energystar.gov
**source: www.hometips.com/buying-guides/high-efficiency-furnaces.html