Fireplace inserts are heavy, often weighing more than 400 pounds. Since wood burning inserts need to be removed when the chimney is being cleaned and maintained, they can be awkward and heavy to handle. It is a job best left to a professional chimney sweep. In some cases, however, you do not have to remove the insert to clean the chimney. The insert can stay in place during cleaning if you install a full relining collar, a stainless steel pipe that connects to the insert and goes to the top of the chimney.
The chimney flue is the pipe that carries the hot gases and soot up and away from the fireplace. They come in two basic styles, metal (prefab) and masonry. There should be metal caps over the flue openings. These hood-like structures prevent rain and snow from falling into the flues and protect the chimney from downdrafts that can force smoke and fumes back into the house.
The flues are also usually equipped with wire mesh to prevent birds, squirrels and other animals from nesting in the chimney. The same mesh will prevent burning ash from reaching the roof or other combustible materials. This mesh should be cleaned from time to time.
Many homes are not equipped with caps. They are inexpensive and can prevent a host of problems.
Your service professional will need to know what type of roof access you have so he or she can plan on what safety equipment to bring.