Lately we've been discussing minimums, the minimum efficiency of central air conditioners in particular. This year the industry has had to move to a 13 SEER minimum efficiency for unitary air conditioners and heat pumps. Of course, there is no legislation for the top efficiency allowable, but there is a market-based threshold.
When it comes to the installation of the system, many contractors assume that consumers have a very low threshold when it comes to costs. In some respects, they are correct. However, some contractors seem willing to cut corners and spend as little time as possible on installations - partly for the sake of keeping costs low for the customer, and partly to be able to move on to the next job.