The physics of smoke rising into a chimney is complex and several things must be done right so all the smoke from the fire exits your home.
Fireplace size for room.
However the most important aspect to consider in order to optimize your fireplace s efficiency is its power its capacity to heat expressed in btu.
The dimensions for a small room are 1 30 of the total rooms square feet to be used as the fireplace opening.
For large rooms 1 65 of the total room footage should be used.
It s a nomograph from the brick industry.
I d hoped to have as big a fireplace as possible up to 60 wide.
From your specs page i ve concluded that 60 is way too big as would be the 48 model.
To properly size a flue you must use a nomograph.
A 36 or 42 fireplace opening width is more common but you need to assume about 18 on each side for a typical non combustible surround and wood mantel 24 on each side for something more grand.
A fireplace will puff smoke into a room if its design is flawed.
The great room that the fireplace will be built in is 16 feet wide by 25 feet deep 400 sq ft with 10 ceilings.
You need enough room to make it look like an actual masonry fireplace.
To calculate what size of fire or stove you will need measure the width length and height of the room or space and multiply the three figures together to obtain the cubic area of the space to be heated.
The same thing goes for stone on each side.
This is a wonderful flue sizing tool.