I found this link to the TN tech center in Crossville and it says the average salary in TN is $14.43 an hour.
http://www.crossville.tec.tn.us/2/hvactechnologies.htm
I found a job for a craftsman/HVAC specialist in Knoxville that starts at $21,386+ depending on experience. That was is working for the government, which tends to pay less than the private sector.
I'm not sure what exactly he would be considered. With him being sort of new in the field, I went with the description for HVAC Mechanic I on salary.com. Again, Knoxville was on the list. It says that the median expected salary is $35,632 in Knoxville.
Granted, I am no expert. This is just what I found researching your question. Another thing to consider is that cost of living may be cheaper in east TN than where you are. I think I saw you are in VA. In TN, you would bring home more money because there is no state income tax.
Hope that helps some.