I recently attended a discussion group at our local Community Collage concerning the new 13 SEER units the government has forced on us.
The bone of contention was the "nominal BTU" the manufacturers are using to compute the 13 SEER. As all of you know the SEER is a ratio of the BTU output of a unit to its input in Watts (actually the SEER is a highbred of the EER which does not take into account the locked-rotor amps encountered at start and the number of start-ups per season, along with various other factors).
It seems the A/C manufacturers cannot make a compressor that produce the 13 SEER under the old ratio criteria (without building a condenser the size of your backyard).
So, what have they done? They have come up with the "nominl BTU." For example (using the simplier EER ratio) a 5-ton unit will produce 60,000 BTUs with an input of 5,000 Watts (20.8 Amps @ 240 VAC).
But, in order to boost the EER up to 13 it would require a compressor that produces 60,000 BTUs with just 19.2 Amps. And such a compressor has not yet been developed. The answer is the "nominal BTU." By fudging on the actul BTU output, the ratio can be manipulated into thinking it is actually putting out 60,000 BTUs when, in actualaty, it is only producing, say, 58,000 or 59,000 BTUs.
So, what does our customer get for his money? A unit that puts out less cooling at the same (or more Wattage) and, therefore, must run longer to cool his home. Net results--no savings!
Comments please (need I ask).