Enhanced heat transfer for low-temperature baseboard heating

Baseboard heating is a major technology for space heating throughout the homes. Hot water from a boiler is circulated through a series of baseboard units to provide heating in cold weather. The baseboard system operates on natural convection due to the temperature difference between the hot water and room air. The vast quantity of installed baseboard in the U.S. is based on a water design temperature of 82 °C (180 °F). High efficiency heating systems, however, such as condensing boilers, heat pumps and solar-based systems often deliver water to baseboards at significantly low temperature, typically 50-55^? C. Such lower water temperatures reduce the performance of existing baseboards to satisfy the heating load. This article explores the feasibility of integrating a forced-air supply for common baseboard radiators to improve their performance when supplied with low-temperature water. The design involves using either small, high-efficiency fans or an educator-based approach that injects a low-speed air stream upward into the bottom section of a baseboard, inducing a larger flow of room air through the baseboard fins. Both numerical simulations and experimental validation will be discussed and compared.