Recently I had observed the cooling capacity of two Window AC's (1.5T) having similar power consumption. The paramters were as under:
1) Brand A- Cooling capacity 4800W, power consumption 1950W
2) Brand B- Cooling capacity 5200W, power consumption 1950W
The manufacturer is claiming higher EER for brand B as per above paramters. My query is :
As the tonnage of both AC's is same they should be having similar cooling capacity whereas the power consumption should be different. As EER= Cooling cap/power consumption, whereas the manufacturer is claiming cooling cap different and similar power consumption.Kindly inform if the manufacturer is correct and also explain the reason for same.

More than likely the manufacturer is correct. They just used the saving on the electric by boosting the cooling power in W/BTU's rather than maintaining the same W/BTU's and the savings showing up as less electric usage.

I feel this is a very confusing way of doing business since most people look at less electrical usage as a sign of the energy savings.

You are gaining aprox 4,000W of cooling power at the same energy cost. So the more efficient model will run less since it is more powerful.

Now if we only new for sure if the manufactures were telling us the absolute truth about the energy usage to start with. LOL

From having written software to measure and test larger units, there are standard EPA tests the manufacturer must document to back up HSPF, SEER and EER. One test for instance measures steady state, which as the test suggests measures your consumption once the unit settles down. There are a number of other tests.

I don't recall the details from PTAC testing and I'm not familiar with window unit testing, but doubt they must follow the same battery of tests. Perhaps a subset. I would have faith in the EER numbers, just don't know at what point in the cooling cycle or how many cycles they measure. So it is distinctly possible for those units to have idential efficiency in the field.

While higher EER window units are good from a national energy perspective, I'd bet the savings from unit B is small enough to be swamped by leaky window installations, oversizing by folks who don't read the box or measure the area they service, popular use in moderate coooling regions of the country, and real world environments. Sounds like a promising PHD thesis.