Hi, Mark here... Yes, I'm new to this forum and thought I ought to get on board so I can learn from all of you out there. I've been in the HVAC business for about 33 years now, I've had my share of frozen fingers, fosgene whiffs, oil sprays, cuts and scrapes so I feel somewhat familiar with the industry. For the last 23 years I've been at the same Industrial facility where there is a ton of variety when it comes to hvac. But now I find myself in a new situation where I feel like a rookie all over again. I've taken up a part time, night job where I teach at a local college to guys who want to get into the business. So I find myself studying even more so than before so I can answer all questions. Thus, I decided to get on board here so I can ask the "cream of the crop". So be patient with me while I try to get familiar with this site and don't laugh too hard when I put my foot in my mouth from time to time. Thanks! I certainly welcome any and all suggestions when it comes to teaching new students of HVAC/R