use old chimney and horizontal run for flue?

[qwertyjjj]

I would like to install a natural gas fireplace in a lounge on a ground floor of a 3 floor building. The building is 100 years old so has 2 old chimneys, which are probably coal chimneys with concrete blocks. Each chimney is at least 15-20ft away from where the natural gas fireplace would be. Is it possible to run a flue horizontally in the ceiling cavity and then up these old chimneys? I assume a liner would have to be installed?

If not, I assume you cannot put a flue coming out at ground floor level out the side of the house, which would be a shorter route?

 

[DAKSY]

You will have to do some research to find acceptable venting configurations for your gas fireplace.
All units are different, based on the testing done by the manufacturers.
Lengthy horizontal runs require even LENGTHIER vertical runs, or the unit will not vent.
As far as a straight horizontal run through an outside wall, again, you will have to look at the install manual for a particular unit.
Because of the dangerously hot temperatures of the vent caps on the outer walls, many manufacturers
dictate a minimum distance to the ground, usually about 7 feet, to prevent contact burns...

 

[qwertyjjj]

Is there a general size for the flue (diameter), wondering if an insert would fit in the old coal chimney.

 

[DAKSY]

Most inserts have a co-linear 3" diameter flexible aluminum vent pipe set.

 

[qwertyjjj]

Most inserts have a co-linear 3" diameter flexible aluminum vent pipe set.

If the vent goes out the side of the building, there's a balcony with another balcony above so it's kind of covered. Attached picture.
What's the code on where the vent can terminate in this case?

 

[DAKSY]

If the vent goes out the side of the building, there's a balcony with another balcony above so it's kind of covered. Attached picture.
What's the code on where the vent can terminate in this case?

Again, you will have to look at the unit's install manual for acceptable venting clearance specifications.

 

[qwertyjjj]

ok, I figured it was more of a building code issue rather than different manufacturers.

 

[DAKSY]

Nope. All units are different. The install manual is the "Bible," unless local codes say otherwise.
Inside each gas (or pellet) appliance manual you will find a page like this: