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SEER and EER are both the ratio between btu/hr of cooling and the amount of watts (power) used. However, the key word is S which stands for "seasonal", because EER is the ratio of btu/hr to watts on the hot operating temperature while SEER is the btu/hr to watts as a number of different temperatures.

I don't know if this is true, but I heard that some of the larger units don't have SEER because they don't have equipment to test something 10 tons or more.

So, they aren't exactly alike and there isn't really a way to convert them. For example....

A unit with two smaller compressors can give you higher SEER values because at cooler temperatures, the unit can run one compressor instead of two, saving power. However two smaller compressors usually can't produce the same amount of cooling at higher temperatures and thus sometimes have lower EER.

Geothermal and water source heat pumps only have EER because they get a constant temperature to work with so since the temperatures don't vary as much, you don't have seasonal values.

HSPF and COP are similar but for heating (COP can also be used for cooling).

Originally Posted by NATEanator

If one can project say 7-10% improvement in efficiency per KW consumed per SEER LVL increase if we are replacing a 20 yr old SEER 6 AIR-2-AIR with a 40 EER GWSHP how is it realisticaly possible to expect a 400% ROI difference with the Geo retro... a conundrum to say the least. That would be kewl if a Waterfurnace would not only run domestic but make my meter spin backwards

May lead some to believe that SEER savings are like MPGs arbitrary numbers of some engineers wishful thinking.

Yes, SEER is a lot like MPG, it is an arbitrary number based on specific tests with specific(supposedly real world, what a bunch of BS) test to compare one unit to another. While cars use City and Highway MPG, heating systems use SEER and EER to test the efficiency of a unit at specific design conditions.

Ah..looks like the water gets muddier

If one can project say 7-10% improvement in efficiency per KW consumed per SEER LVL increase if we are replacing a 20 yr old SEER 6 AIR-2-AIR with a 40 EER GWSHP how is it realisticaly possible to expect a 400% ROI difference with the Geo retro... a conundrum to say the least. That would be kewl if a Waterfurnace would not only run domestic but make my meter spin backwards

May lead some to believe that SEER savings are like MPGs arbitrary numbers of some engineers wishful thinking.

The easier way is that all units rated in SEER also have an EER rating, for example a Trane XL20i with an air handler has a SEER of 19 and an EER of 13.5, however SEER and EER are not tied together because they also have three other match's with an air handler all are 13 EER yet one is 18.5 SEER and the other two are 18 SEER. Both ratings provide efficiencies that give you a small snapshot in time, however it is usually fair to say that you can conservativly add 20% to get a very estimated SEER equivalent. So a 30 EER ground source heat pump is hitting close to 36 SEER

EER is the imperial equivalent of COP. There is no unusual weighing.

It is derived strictly from power input and work done. COP depends on condensing and evaporating temperature.

For example, a freezer with COP of 0.7 @ -5F evaporator temperature means that it is evacuating heat at the rate of 70W while consuming electricity at rate of 100W.

Then... EER = COP * 3.412

SEER uses different averaging method. A lot of explanation is given here:
http://en.wikipedia.org/wiki/Seasona...ficiency_ratio

EER vs SEER

I realize this may hv been discussed to ad nauseum before but how can I convert SEER to EER equivalent...every unit has its EER but is there a conversion formula out there?