I was told that I could save up to 50% on my utility bills with a new 18 (19, 20, 22) SEER efficiency system
There are two efficiency ratings for A/C systems:
- SEER (rated at average annual outdoor temperature, typically below 80ºF)
- EER (rated at standard 95⁰F outdoor temperature)
While most manufactures boast new products efficiencies up to 23 SEER, yet the same products EER numbers seem to get stuck around 13 …
Let us start with dollar figure, according to FPL guide, annual cooling cost to run a 3-ton (36,000 BTU/Hour) installed in the 1990s with a 10 SEER will be $1,210. If replaced with a new 20 SEER system, the cost drops to $600 - a savings of $610 per year or about 35% drop of your total utility bill which is still impressive, isn’t it? Well, not really. For starter let’s take a look at the definition of this rating: Seasonal Energy Efficiency Ratio (SEER). The total heat removed from the conditioned space during the annual cooling season, expressed in Btu’s, divided by the total electrical energy consumed by the air conditioner or heat pump during the same season, expressed in watt-hours. In plain English, this means that one could take conditions in Seattle (average annual cooling hours 200 ) and in Miami (annual cooling hours 2800) mix them together, add seasonal temperature fluctuations and get this state of the art formula for national average efficiency rating. By this SEER protocol some hypothetical national average customer living somewhere in Midwest with average 1,000 annual cooling hours and outdoor air temperature below 77ºF (why not just open windows) 60% of the time and only 7% of the time ambient temperature climbing above 90ºF would probably enjoy around $250 saving per year with 20 SEER system. That is how it appears Seasonal Energy Efficiency Ratio is determined by ANSI/AHRI STANDARD 210/240-2008 (see page 99). As a matter of fact, 20% of the time system is tested at 67⁰F ambient temperature to determine its SEER.
What about our fellow Floridian who is about to pay pretty stiff premium for this ultra efficient 22 SEER system. In order to determine actual saving we would refer him to EER rating system instead: Energy Efficiency Ratio (EER). A ratio of the cooling capacity in Btu/h to the power input value in watts at any given set of Rating Conditions expressed in Btu/(W⋅h). Translation – energy consumption is determined at Standard Rating Conditions (vs. stated Rating Conditions for SEER), which is constant 95⁰F outside and 80⁰F inside (looks familiar?). Now let’s take a look at one certain product – AHRI Directory (type in PSA4BI036K for outdoor unit, B6V for indoor unit) Maytag 3 Ton 22 SEER, 14 EER system. Applying EER yardstick the same system would result in more realistic (and accurate in our opinion) $350 annual savings or, by our guesstimate, about 25 years to recoup the original investment (though in fairness we should say it is a nice looking system) If we compare it to AHRI Directory ( type in MSA4BF for outdoor unit, B6V for indoor unit) Maytag 3 Ton 16SEER, 13EER system, the same FPL chart (substitute SEER with EER) would show $280 annual savings or, by the same guesstimate, given much lower system price, about 15 years to recoup original investment. If you take the time to compare other brands performance, trust us, they are not going to fare any better, you will not find a system higher than 14EER. The truth of the matter is that it is very difficult to figure out actual savings, EER number appears to be more accurate for Florida, our experience and totally non scientific approach recommends to add one EER for variable speed air handlers and another EER for two stage/ variable speed compressor, chasing just SEER number probably is counterproductive – you might be better off investing in low E- value windows or spray foam attic insulation.