— By Jerry Dill — When it comes to choosing HVAC air distribution products, there is more than meets the eye. How often have you heard the saying “You can’t judge a book by its cover?” Plenty, I’m sure. Typically when you hear the phrase, it is in reference to people. But today it can apply universally to just about anything. The same can be said, even, about new HVAC air distribution products such as grilles, registers and diffusers. You can find supplies and returns in just about …