Stove with Through the Wall Chimney Installation

Through the Wall Installation

In through the wall chimney installations, the chimney enters the house through a vertical wall rather than the ceiling (see through-the-wall illustration). This requires the use of an insulated tee with cleanout plug, a wall support, wall closure or cover plate, wall bands, roof flashing, storm collar and chimney cap. The illustration also shows a wall radiation shield, firestop, roof radiation shield, trim collar, and finishing collar. Cleanout access should be provided beneath the tee cleanout plug.

It is important to follow manufacturer's instructions regarding the minimum length of chimney that must extend into the living area (as well as instructions regarding the maximum horizontal run of chimney). Some chimney manufacturers offer adjustable length sections to simplify determining horizontal chimney and connector lengths needed from the tee to the stove. For other factory-built chimneys that do not have adjustable lengths (and of course, cannot be cut) the distance from the insulated tee (which the wall support positions in a fixed place) to the chimney's minimum protrusion into the room must be made up with a standard chimney length or combination of lengths that meet or exceed the minimum length needed. The length needed will be the sum of the space between the tee and the outside wall, the overall thickness of the wall, and the minimum extension into the house.

An exterior chimney is subject to cold outdoor temperatures, leading to greater heat loss and higher rates of creosote accumulation and moisture condensation in the chimney. The best location for chimneys for optimum performance and draft is on an interior wall of the house. Cold hearth syndrome spillage is more likely with exterior, through the wall chimneys, particularly in basement installations.

Bends like the 90 degree tee and any connector elbows in a chimney restrict flue gas flow and affect draft. Through-the-wall installations are also more expensive than entirely vertical installations. A better performing alternative to through-the-wall may be an interior chase (through upper floors for a basement installation.)

Consideration must be given not only to safety code height for the chimney, but also to draft requirements. Additional height above code minimums may be called for. In any event, roof bracing may be needed.