Abstract
Since hot-water supply has high percentage of energy consumption in residential sector, improvement in the efficiency of a gas water heater is an important issue. In order to improve thermal the efficiency of a gas water heater, an additional heat exchanger is required for latent heat recovery from the exhaust humid combustion. In this paper, the history of gas water heater, the technologies developed for latent heat recovery gas water heater and the recent progresses in the development of latent heat recovery heat exchanger are presented.
