Just wondering if germicidal lights installed on furnace really work. Are they safe and is it worth the money? Thanks

I wouldn't recommend it becaucse the germicidal lights have a high resolution that is bright to do the human eye. Another thing to keep in mind is that some UV lights have good wavelengths and others destroy the ozone. Keep in mind that a good germicidal light will damage your eyes and having it been installed in a furnace is not the best idea either .