When shopping for furnaces, boilers, and air conditioners, you will come across various efficiency ratings. The salesman will prattle on about how one rating means this and another means that, but how are you going to know what really is best? You need to have a good understanding of just how efficiency ratings are determined, and what a good efficiency rating is compared to a bad one. The more you understand about the investment you are about to make, the better decision you will choose.
Furnaces and Boilers
Furnaces and boilers are the two most popular systems used in the United States to achieve heating for residential homes. There are several different types of each unit, but the majorities are either run on natural gas or electricity. Depending on the application that you are using this heating system for, the type of fuel you choose may differ. For those who live in colder climates, a gas powered furnace or boiler would probably be their best bet. Gas prices are typically lower, and gas heat provides a more comfortable heat distribution throughout the home. Electric furnaces are recommended for homes that don’t require as much heat or that are in areas with low electricity costs. Electric radiators are a good option to add supplemental heat to a room in a home that has another heating source already in place.
Understanding AFUE
The type or fuel used directly effects the efficiency or AFUE rating for a particular furnace or boiler. AFUE stands for Annual Fuel Utilization Efficiency. The rating that a system has will be represented by a percentage. That percentage corresponds to how much fuel is being used to generate heat and how much is being wasted. For example, a gas furnace that has an 80% AFUE rating turns 80% of its fuel into heat, and 20% of its fuel is lost in the combustion process. If you have an old gas powered furnace, odds are the efficiency rating is between 68% and 72% AFUE. That’s pathetic. Nowadays you can find gas furnaces on the market that reach efficiencies between 90% and 97%.
Electric furnaces may cost more to operate, but they are very energy efficient. They often have AFUE ratings between 95% and 100%! That is because there is no flue lost through the venting system. As the cost of natural gas continues to increase, this type of furnace may become more practical in the United States. However, alternative renewable fuel sources are the best option over all, but the conversion is often too costly or unrealistic for many areas of the country. For now, we have to best with what we have, and that means purchasing high efficiency heating systems.
Air Conditioner Efficiency
Cooling systems are on a completely different scale. SEER or Seasonal Energy Efficiency Ratio is a way of expressing the efficiency of a central air conditioner. It is the measurement of the amount of British thermal units per hour of cooling, per watt of electricity. Basically what that means is the higher the SEER rating, the better the unit uses its fuel. Up until 2006, there was not a SEER requirement placed upon manufacturers of air conditioners, so if you purchased your unit before then it probably has a SEER rating between 6 and 10. The requirement is now 13 or higher!
Replacing that old air conditioner with a new high efficiency unit could greatly decrease your energy bills during the summer months. You could even find air conditioners that have up to a 23 SEER rating. If you had your air conditioner installed in the 70s you could save 30-50% by upgrading, and even if you only replaced the unit within the past 10 years, you could still save 20-40% by upgrading your central air conditioner.
At this point you should have a much better overall understanding of how energy efficiencies are determined, and you should also be able to make a more educated decision when it does come time to upgrade. The investment in heating and cooling systems is already a big one, so you might as well get a unit with the highest efficiency possible to increase your savings in the long run.
