Can A Vented Pan Burner Set Be Converted For Vent-Free Use?

Question: We have a vented pan burner gas log set that has to be vented. Is there any way that this can be converted to a vent free log set?

Answer: Vented pan burner gas log sets are only for use in a fully vented wood burning fireplace. They cannot be converted for vent-free use, as vent-free sets are designed to a very different and more restrictive standard.

Burner design is the biggest difference between vented and vent-free sets. Vented Pan-type burners are designed to burn with a smoky, wood-like flame which will produce soot. All vent-free gas log sets on the market are certified to the national standard for vent-free heaters, ANSI Z21.11.2. By the ANSI standard, vent-free gas log sets must be designed so that they do not produce soot. Rasmussen vent-free sets use a state-of-the-art louvered-port burner. This type of burner is very forgiving when operated under adverse conditions, such as improper log placement or drafts. Such conditions result in the flame impinging on the logs, which cause soot to from our competitors' punched-port burners, but operate clean with the Rasmussen burners.

The maximum Carbon Monoxide allowed by the ANSI standard for vent-free heaters is the lowest permitted by any gas burning appliance (220 PPM air free).

By contrast, the standard for a kitchen range, which is also an unvented appliance, allows up to 800 ppm air free.

All vent-free gas log sets must be equipped with an Oxygen Depletion Shutdown system, which consists of a calibrated pilot and safety control valve. The set must shut down before the level of oxygen reaches less than 18.0% (20.9% is normal; 15.0% can cause death).

The maximum allowable gas consumption by standard for a vent-free heater is 40,000 BTU/hour. This helps limit the amount of the products of combustion that are produced, but ultimately it is the burner design, the positioning of the logs (log can either add to or subtract from the performance of a gas log set, depending on the design) and the experience of the manufacturer that creates a vent-free set that will not only pass the rigorous testing to gain certification, but also perform well in the home environment, which is much more "hostile" than a laboratory situation.