To add a little bit more to what Chris told you, our Fire Department recently purchased a thermal imaging camera from a company by the name of Bullard, located in Kentucky (sorry, I don't know the city). We use this for locating hot spots inside walls and ceilings (from fire, ballasts, or high resistance electric connections which are "cooking" in a hidden area). Works great, but the cost of this thing is horrendous...$9800.00!
Hopefully, someone can put you onto something a little more reasonable.
Found a URL for this company... http://thermalimager.bullard.com/whybullard/
(along with an address and phone numbers)
[This message has been edited by mamills (edited 02-14-2002).]