The Energy Efficiency of Hot Water Production by Gas Water Heaters with a Combustion Chamber Sealed with Respect to the Room

Grzegorz Czerski,Andrzej Strugała

doi:10.3390/w6082394

Abstract

This paper presents investigative results of the energy efficiency of hot water production for sanitary uses by means of gas-fired water heaters with the combustion chamber sealed with respect to the room in single-family houses and multi-story buildings. Additionally, calculations were made of the influence of pre-heating the air for combustion in the chimney and air supply system on the energy efficiency of hot water production. CFD (Computational Fluid Dynamics) software was used for calculation of the heat exchange in this kind of system. The studies and calculations have shown that the use of gas water heaters with a combustion chamber sealed with respect to the room significantly increases the efficiency of hot water production when compared to traditional heaters. It has also been proven that the pre-heating of combustion air in concentric chimney and air supply ducts essentially improves the energy efficiency of gas appliances for hot water production.

Highlights

In recent years in developed countries, energy consumption in buildings has been increasing dramatically; in the EU, for example, it is greater than in the industry and transport sectors [1]
Appliances with the combustion chamber sealed with respect to the room, only recently available on the market, are equipped with fans that enable a reduction of the temperature of the combustion gases to about 100 °C, resulting in a significant improvement in the energy efficiency of the appliances
The aim of this paper is to show that the application of gas heaters with the combustion chamber sealed with respect to the room increases the energy efficiency of hot water production in residential buildings

Summary

Introduction

In recent years in developed countries, energy consumption in buildings has been increasing dramatically; in the EU, for example, it is greater than in the industry and transport sectors [1]. Hot water is produced by means of a number of appliances using energy either from fuel burning, or electric and solar energy, in addition to the use of heat pumps. In the case of gas-fired instantaneous water heaters, appliances with an open combustion chamber have far been used most frequently. They evacuate combustion gases by natural draft, and, the temperature of combustion gases has to be appropriately high (above 150 °C), which results in a relatively low efficiency of those appliances (80%–87% in relation to the lower heating value). The use of gas appliances with the combustion chamber sealed with respect to the room enables saving energy through a reduced demand for air necessary for the ventilation of the flats. In the case of appliances with an open combustion chamber, there is a risk of their users being poisoned with toxic carbon monoxide [5,6,7]

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