Before installing a garage door opener, you should be able to open and close the door easily with one hand. The door should be lightweight and operate smoothly in both the up and down direction. If the door sticks or binds, the door is out of alignment and will need to be serviced by a professionalIf you open the door half way and then release it; the door should remain in place completely supported by its springs. If the door begins to fall towards the floor or starts to rise upwards, the door is out of balance and will need to be serviced by a professional.
Generally speaking, If you have a two car garage door, a (1/3) or (1/2) horsepower garage door opener is sufficient. For a heavier door, like a carriage door which is three and ½ inches thick or thicker, we recommend a (3/4) horsepower model. The (3/4) horsepower system is designed for use on sectional doors only.
Remember that the easier it is to open your door manually, the easier it will be for your garage door opener to operate the door, and that means your garage door opener will last longer.