Radiant versus Heat Circulating

When choosing your fireplace, you'll need to think about whether you want radiant or heat circulating. If you don't know the difference, the following information should give you some help to make your decision.

Radiant heat is infra-red radiation, emitted by a hot surface, that strikes objects in its path. A radiant fireplace is a fireplace that heats by emitting infra-red radiation. Fire heats the fireplace and the fireplace emits infra-red radiation (which heats you.) With a radiant fireplace, install your insert into your cabinet or surround and create a smooth appearance with only the viewing area of your fireplace showing as in the picture on the right.

	Circulating fireplaces heat air. Heat is transferred to air moving across the hot surface. The air heats up and rises. The rising air draws more air up after it, causing circulation of air. A circulating fireplace uses panels spaced out from the firebox allowing air to circulate between the firebox and the panels. Some models need optional louvers to complete the unit. The baffles used to circulate the air will be showing on the top and bottom of your fireplace as in the picture on the right.
Some people simply like radiant heat rather than convective heat as distributed by the circulating stove. However, if young children are in the family, consider the circulating stove; its surface temperature is much cooler than that of the radiant stove and fewer burns would result. When selecting a stove, also weigh the improved efficiency, and thereby lower wood requirement, of the airtight stove versus the nonairtight, which is lower priced. Airflow requirements are important as a certain airflow must be maintained to support adequate combustion; much lower flow is needed for the more tightly constructed stoves than the loosely constructed stoves or fireplaces. Because recently constructed and well maintained houses are tighter than those built 25 or more years ago, problems sometimes occur when ventilation air is not adequate to operate a fireplace or open stove.
So, what's the difference? The fact is, all stoves produce both radiant and circulating effects. There are always air currents around any hot object. And hot objects always emit infra-red radiation. The distinction is that a stove in the radiant category does not have panels designed to increase air circulation around the firebox, while a circulating stove does. Which is better: radiant or circulating? This depends on the installation. One advantage of circulating stoves is that the temperature of the outer panels is much lower than the surface temperature of a radiant stove. (Because, of course, air is circulating between the firebox and the jacket, drawing heat away.) And the amount of infra-red radiation emitted is lower, as well, since the outer jacket absorbs some of it. This allows for closer clearances to combustible materials in the home such as Sheetrock or wood walls. On the other hand, many people prefer the look of more traditional, cast-iron stoves, which tend to be designed as radiant heaters. Both types are effective heaters. In the final analysis, installation safety and personal style preferences are more important factors than radiant vs. circulating design.

Excerpts from The Clemson University Cooperative Extension Service