I'm so bummed! We put in a new HVAC system including ducts last year as this house was a foreclosure and there was mold in the old system. It cost $14,500, but we were given the cert. that was supposed to get us the $1500 credit back on our taxes. Long story short, this credit is once in a LIFETIME per taxpayer and we already claimed it in 2009 when we replaced the HVAC on our old house. I wish that I'd known that when we got the work done because perhaps I could have gotten the price down by that amount because we weren't getting the credit. I'm pretty sure that the contractors' prices are padded to reflect the credit now.