It is important to balance the air flow to meet the needs and desired temperature of each room of your home.
All you need to do is remove the grills from each room. Reach up inside the air duct and adjust the damper
by adjusting it with your hand to increase or decrease the air flow to meet the desired temperature of each room.
This will need to be done with the seasonal temperature changes. This will save you money in the long run and will
keep all your room to the desired temperatures. This will not create a howling sound like when you close your grills
to adjust air flow. Call me if you need further help or advice. Randal.