A local Plumbing contractor says the following:

€œIn the case of a central heating and air conditioning system, closing off vents
has the same effect as a dirty air filter. It simply restricts airflow. Heating
systems are designed to heat the whole home and are sized accordingly. Shutting
off a section of airflow increases the air pressure in the system, in turn
increasing the amount of duct work leakage."

"A more energy efficient way to control individual temperatures in unused rooms
is by using a ductless heating and cooling mini split systems that are mounted
on the wall and wired using a simple wiring process to an outdoor unit. No ducts
are used so installation doesnt take much time at all. Ductless heating and
cooling mini split systems are a flexible solution.€�

My question: Is closing the ducts to three unused bedrooms and an unused
bathroom a bad idea and it wont save any money on the gas bill?