So, since getting the system up in 1/2005, the air conditioning broke twice in the summer of 2005,  the heat broke in the winter of 2005, the heat broke again in the winter of 2006, and the air conditioning broke in the summer of 2007, and now the heat broke again in the summer of 2008.  Now, this system was installed by people hired by Virginia Design Builders/ Dan Lopez of Laurel, MD.  The contract price was $10,000 for the upgrade (as one stage of a $72,000 job that cost $84,000 or so).  It pretty much took 3 or 4 men a week to install it.  For multiple repairs, the repairman has not understood what has gone wrong, but just happened to make it work again.  Supposedly Dan Lopez has retired, but his children are running his company in Maryland.  Beware. I expect such incompetence in managing a project to be hereditary.