(This information appeared in the June 2012 issue of Sweeping magazine as a technical article by Rett Rasmussen)
Q – Is a gas log set a cure for a smoking (non-drafting) fireplace?
A – Yes and no. Most sweeps have worked on a fireplace that, despite applying a cap, trimming back trees, lengthening the stack and many other tricks of the trade, they just can’t seem to correct the drafting problem. Gas logs come to mind as a possible solution, but which kind you use can either continue the problem or provide a viable solution for providing a flame in the fireplace.
Vented gas logs are designed for their decorative replication of a wood fire. Pan burners used in most vented sets burn with a yellow smoky wood-like flame that produces soot. If the soot does not go up the chimney, it will go out into the room, which is a hazard to health and furnishings. If the fireplace has a drafting problem, a vented gas log set is definitely not a proper solution.
Vent-free gas log sets, however, are designed and certified to the strictest of all gas appliance standards (ANSI Z21.11.2). This standard has the lowest carbon monoxide limits of all gas appliance standards. It also requires that no soot can be produced. Vent-free sets are designed to be used in fireplaces without a flue, which is equivalent to not having proper draft. Installing a gas log set designed and certified to the vent-free standard is definitely an option for a fireplace that does not draft.
Vent-free sets are limited to 30-inch set size and smaller, as the standard also caps the maximum gas input at 40,000 BTU/hour. Vent-free gas log sets are not a solution for larger fireplaces.
Other solutions for a non-drafting fireplace are to put candles, a stack of not-to-be-burned logs, electric logs or a plant. While all of these would fill the fireplace opening, they are by no means a substitute for a real flame. Chimney specialists should have a couple of “go-to” vent-free gas log sets in their back pocket to recommend to their clients with incurable smoking fireplaces so that they may enjoy the warmth of an open flame with the convenience of gas. Be sure to offer your client an annual safety and maintenance inspection of the gas log set and chimney, for a reasonable price, to keep an ongoing relationship with them.