Our school, Greeneville/Greene County Center For Technology in Tennessee, has been using the Clean Air America systems for nearly 10 years now. These eleven systems have worked great with no problems at all.  Once every semester, we simply blow out the air filters (twice a year) and they keep on working perfectly. These systems work excellent for all phases and types of welding fumes. Another thing we like is how Clean Air America checks in with the school two to three times a year to see if we are happy with the systems and if they can do anything else to help with our ventilation needs. Thanks for your follow ups – we appreciate it.