Tankless Water Heater Research Articles

Achieving water conservation and energy efficiency with electric tankless water heaters

This article discusses reducing water loss and increasing energy efficiency by using electric tankless water heaters installed close to the point of use. This type of water heater reduces wait time for hot water to reach the fixture, along with the time it takes to adjust the temperature of the water. These hot water heaters require less piping for transporting hot water, and thus reduce the amount of leakage resulting from corroded pipes. Electric tankless water heaters also save energy by essentially using zero energy when there is no hot water demand.

Development of a Model Predictive Controller for Tankless Water Heaters

This paper describes the development of a novel approach to temperature control of tankless water heaters (TWHs). Conventional methods of controlling TWHs typically allow a high degree of error in the outlet water temperature when subjected to disturbances in flow rate or inlet water temperature. Poor control affects comfort, safety, and energy consumption associated with TWHs. The novel control approach presented here uses model predictive control (MPC) to minimize the outlet temperature error. A dynamic heat transfer model of an electric TWH is developed and validated and used within a MPC-based controller. The controller is interfaced to a physical prototype TWH and tested using an experimental test bed developed for this project. An integral performance criterion is used to compare performance and to tune the MPC in a standardized series of tests, also developed for this project. MPC is shown to provide excellent control of the prototype TWH.

Improving the Gas Instantaneous Water Heaters Performances

This study presents a study of a theoretical and practical investigation of the gas Instantaneous (Tankless) water Heaters performance. The results allow us to obtain realistic values of the control system in the various capacities gaseous flowing water heaters. The objective of this work is to study the operation of the plans in the field of controlling and checking low capacity gaseous flowing water in order to choose the proper plan of the logical values and measures for these equipments that may be used in industrial conditions. Also results of the work proved to be accurate. A design of the control system was made. The results of the practical experiment of the control system were similar to the arithmetic results.

97/03868 Strategies to address transition costs in a restructuring electricity industry

Fuel cells with nominal outputs of approximately 1 kWAC are emerging as a prime-mover of a micro-cogeneration system potentially well-suited to compete, on an energy basis, with conventional methods for satisfying occupant electrical and thermal demands in a residential application. As the energy benefits of these systems can be incremental when compared to efficient conventional methods, it is especially important to consider the uncertainties of the models on which simulation results are based. However, researchers have yet to take this aspect into account.This article makes a contribution by demonstrating how these model uncertainties may be propagated to the simulation results of a micro-cogeneration system for comparison to a reference scenario using a case study. This case study compares the energy performance of a fuel-cell based micro-cogeneration system serving only domestic hot water demands to an efficient reference scenario where the conventional methods for providing electrical and thermal demands are considered to be a central gas-fired combined-cycle plant and a condensing tankless water heater respectively. The simulation results demonstrated that if model uncertainties were ignored, it would have been possible to demonstrate that the considered micro-cogeneration system was more efficient than the reference scenario for average consumption levels of domestic hot water. However, when model uncertainties were considered, the efficiency of the considered micro-cogeneration system could not reliably exceed that of the reference scenario by serving the domestic hot water needs of a single-family home.