I am buying the house my mother has been renting. I live three hours away and could not be at the home inspection. However, the inspector's report stated that the HVAC system need an insulated boot register. The seller balked at making this repair because he was told that it was not required by "the code".

I do not know what a boot register is, how important it is or how much it would cost to get it repaired/installed. Any help on this would be greatly appreciated.