How much heat do you need?
Your new stove will need to physically fit into your firplace or room but it is also important to consider that the stoves output is sufficient for the room.
Ensure also, that it's not too large for the room, as this can cause just as many problems as a stove that is too small. A stove that is too small will not be powerful enough to heat the room adequately. On the other hand, if you have a stove that is too big an output, it will need constant attention to keep the temperature down. A result of this is the combustion within the stove will not be complete and you will quickly have a build up of soot not just on the glass, but in the chimney also.