Before you jump into a high SEER unit, you better pay attention to EER because you live in Texas which is not a SEER state.
First, let me explain...
SEER on a single stage unit is measured at, for argument's sake, 82 degrees outside and 80 inside. Seer for a multistage unit is measured at what is called the "Bin method". Now they test it at 80 inside but they test the OD temps at 57, 62, 67, 72, 77, 82, 87, 92 and 97. However 70% of the weighted results come from 82 and below. only about 5% come from the 92-97 degree range. How efficient is a system when it's below 77 outside and 80 degrees in the house? Pretty efficient, as it spends a good percentage Off! and off cycles are included.
California, after dealing with rolling brown and black outs has found that SEER has done nothing to reduce the energy requirements of the state. They have sued and now the law requires EER to be posted along with SEER. EER is your hot weather efficiency, SEER is your mild weather efficiency. Living in Texas, I suspect you are concerend with hot weather efficiency.
I will tell you this, look at EER for every system you are considering and then look at the cost. I suspect you will find that you will get a 16 SEER unit that will perform very admerably against a 18+ SEER system when it comes to EER at a more reasonable cost.
Somehow, this industry is racing to produce the highest efficiency mild weather air conditioners and now that EER's are being included, you will see a change in attitude as more people are educated (including contractors).
Also, be careful with the matches on a system advertised at "high SEER", putting a number in the "model" is a means of letting you assume. If I call my unit the 19BDE or the 21SFE you will assume the 19 or 21 is a legitamate SEER or EER standard, it's not. It never was and never will be. I was thinking we should market a 13 SEER system as the 25FU series just to watch the goobers flock.
I'm on your side here, just suggesting buyer beware.
Finally, someone else understands and posts that the nature of the SEER calculation is geared to low outdoor temps. A high SEER system does not automatically mean increased energy savings, unless it is accompanied by a high EER#. For a variable speed fan in the air handler, the bin temps are actually from 67 to 102 in 5 degree increments. 67F accounts for 21.4% of the value of the SEER calculation. Who runs their central a/c at these temps? Nobody. The highest 3 temps (92, 97, and 102F) account for only 7.4% of the value of the SEER calc. Who runs their central a/c system at these temps? Everyone.
Originally Posted by docholiday
Thank you for that post and take care.
This is IMHO excellent information. I've asked several contractors giving me bids about EER and have gotten responses ranging from a condescending, "No, it's SEER, not ear" to "That number is only important to the power company."
Originally Posted by docholiday
I'm in TX and the system I specced for my house is a single stage with 15 SEER/12 EER and VS air handler. FWIW.
EER = system cooling btus / condenser power draw in watts measured at 95F laboratory conditions at steady state conditions.
Originally Posted by irwin_fletcher
With today's systems, an EER of 12 is excellent, >12 is outstanding.
A system that has a high EER# produces the same number of btus with a lower condenser power draw = lower operating costs (at real world summer conditions). As the outdoor temps drop from 95 degrees, the EER increases from the rated number because there are more btus produced at lower power draw.
EER, however, does not account for compressor cycling on/off or the time it takes the system to get to steady state conditions.
Note that 16, 19, and 23 SEER systems use dual-stage, dual compressor, or variable speed compressors respectively to achieve the high SEER numbers (at a much greater purchase cost to the homeowner).
Double check the manual J, bin data.
All of the Texas listings show far more hours between 75 and 85( where SEER is more of an indicator then EER ), then above 85( where EER is the better indicator ).
In cal, don't they also have zones where if you put in a 14 SEER your duct doesn' need to be as high of an R value.(kind of defeats the purpose of high efficiency.)
Cal, has more trouble electric troubles then just the ratings of A/C systems.
Unless your setting your stat to 80, neither is a true representation of its efficiency.
But each has its place, and shouldn't be shot down without knowing the the locations bin data.
No, I dont have all the details and I know nobody uses an 80 degree set point but if you set your stat lower, your run times increase. A multistage unit will probably have no off cycles once you get to 85 degrees so it only strengthens my case that SEER in the south on multistage equipemnt is misleading at best. If your EER sucks, it offsets the potential savings by some imaginary SEER number.
All I am saying is when you get into two stage machines the calculations for SEER are piss-poor to say the least. In 13 SEER, single stage systems, it's closer to realistic.
Hey, sell anything you want, but when they dont see a 60-75% reduction in their cooling costs they might come asking why not. For that kind of money you would be better off buying a good 16 SEER unit with a high EER and notice no difference in the cost of operation. Why fork out good money for unrealized savings? This is one case where you cant sell a comfort advantage over a two stage machine.
Actually, I've never sold a 2 stage as an energy saving system.
I sell them for what they are. Increased comfort systems.
The highest SEER unit I pulled and replaced with a 15 SEER 2 stage was a 12 SEER.
Roughly a 20% reduction in the cooling bill, from what the customer told me. They were able to set their stat higher due to the reduced humidity. It was a York Stealth, and uses the Bristol TS compressor.
The real test results will start to come in, in another 5 years. And continue to come in for some years after that.
When we all start to pull the 12 SEERS that were installed in the 90's, and a greater asortment of 13, 14, and 15+ SEER units are installed in their place.
And the RNC homes that have been getting 13 SEERs installed, begin to waant better units.
Till then, its a lot of spectulation.