SEERS, EERS and Tons, Oh My!

wizard_of_oz_dorothyShopping for a new air conditioner or heat pump can seem like a daunting task with all the technical lingo and acronyms. Many variables go into choosing a new air conditioner or heat pump. Three of the most important terms to understand are SEER, EERS and Tons. So let’s start with some basic definitions.

SEER stands for Seasonal Energy Efficiency Ratio which indicates the relative amount of energy needed to provide a specific cooling output. Many older systems have SEER ratings of 6 or less. The minimum SEER allowed today is 13. In general terms, the higher the SEER the higher the efficiency.

EER stands for Energy Efficiency Ratio. The EER is the ratio of the cooling capacity (in British thermal units [Btu] per hour) to the power input (in watts). The higher the EER rating, the more efficient the air conditioner.

Screenshot_11_14_13_10_42_AMSo what exactly is the difference between SEER and EER?

EER is a measurement of the efficiency of a cooling system when the outdoor temperature is at specific levels. SEER is used to measure the efficiency of a cooling system over an entire season. Almost all residential units are measured in SEER.

EER can be measured directly, whereas, SEER is determined only by predictions, because of unpredictable weather conditions. SEER is always tested at the manufacturer’s establishment, and therefore, it is better to focus more on SEER.

At the end of the day, both SEER and EER can be very useful for comparing different air conditioning units to one another, but are not the end of the road to increasing efficiency and decreasing energy costs. More importantly than SEER or EER would be an HVAC unit’s size.

ice-king-blocksAC units are measured in ‘tons’. What is a ‘ton’ of AC you ask. Historically a ‘ton’ was the amount of heat removed by 1 ton of ice every 24 hours. Nowadays, 1 ton is defined as 12,000 BTU/hr, and 1 BTU = 1.06 kJ. So the 5000 BTU/hr air conditioner is a 0.42 ton unit.

There are lots of variables that go into determining the proper sizing of an Air Conditioner or Heat Pump including overall square footage of the house, type of insulation, room layout and the size/insulation value of the windows and which direction they face.

So with these definitions, it would seem logical to assume that with SEER, EER and tons – that bigger is better. But is this true?

for-print-media-size-mattersIn short….no. Obvious bad jokes aside, bigger is not always better and size does matter. Proper sizing is arguably THE most important in deciding which unit to go with. Too small a unit will not be able to attain a comfortable temperature on the hottest days. Improper unit location, lack of insulation, and improper duct installation can also greatly diminish efficiency and make an undersized unit run constantly, reducing its life and negating the energy savings of the higher efficiency.

Too large a unit will not adequately remove humidity as they cool and shut down too quickly to remove the humidity. So you may be left with a cool home that still leaves you feeling clammy and sticky. Oversized units also tend to short cycle which is very hard on the components and can significantly reduce the life span of the equipment.

But surely the higher the SEER/EER the better?

Yes and no. By strict definition the higher the SEER will always equate to a more efficient system and lower energy costs to run them which in turn is better for your monthly utility bills and the environment. But conversely, most of the higher SEER systems lose cooling power more rapidly at higher outdoor temperatures because they have smaller compressors. So on a really hot day the higher SEER may not provide higher comfort. Here in Pennsylvania our summers are typically not as brutal as say the deep south, but conversely our winters are more harsh. In that light, the higher SEER almost always makes sense when you are talking about a heat pump (which also heats the home) versus a straight air conditioning unit.

Another thing to take into account is that higher SEER units also come with a higher price tag. How long you plan to stay in your home has to be taken into account when determining how long it will take to see the return on investment.

There are other factors too, such as single speed vs. variable speed, that we have not touched on here. With all the available options to consider choosing the best equipment can be challenging. We are here to help you make the best choice for your home, your family and your wallet. Call us today for a free consultation with one of our specially trained technicians who will walk you through all the technicalities and help you make the best decision possible and provide you with the highest level of comfort and savings for many years to come.



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