Using a fireplace insert is a wonderful way to create an efficient heat producing appliance out of a very inefficient fireplace. For an insert to be effective it must have a blower, or you will just be isolating all the heat in the fireplace and using its radiant energy. A good fireplace insert with a blower can easily heat a medium-sized home. If your insert has a place for a blower, here is how you should install it.
Open the compartment on the fireplace insert where the blower should be. Obviously, this should only be done when the fireplace insert is cool. Remove the screws holding the cover in place. Sometimes the screws may be hard to remove and you may have to use a little WD-40 and let them sit for a few minutes before trying to unscrew them. Keep the screws in a safe spot along with the cover for when you are ready to reinstall it.
Remove the old blower motor if it is still in place. Unplug the blower from the power source. Unscrew any screws on the mounting bracket and carefully pull the motor out of the compartment. It could be very dusty so have some newspaper or a drop cloth handy to put it down on. Disconnect any wiring and set the motor aside.
Vacuum out the compartment thoroughly with a shop vac or a vacuum cleaner with a hose. You will only be able to reach back so far, so clean as much as you can. Some of the dust might have hardened on the sides and in the corners from years of being blown. You might have to loosen with a brush and then vacuum.
Check the serial number on the motor and replace the motor with another of the same number. If you are not replacing a motor, check with the manufacturer to see what size motor you should get. It will need to be a certain type of motor to achieve the efficiency rating.
Wire the new motor to the existing wiring exposed from the previous motor. If you are not familiar with wiring, have a licensed electrician do this for you. It is a simple procedure, and should not take him more than a few minutes.
Set the motor into the compartment using the support bracket to secure it in place. Screw it in securely or you will have an irritating vibration later. Now try turning the motor on to see if the connections are still solid. If it works well, replace the cover plate with the screws set aside earlier. If the motor does not come on, check the wiring connections.