This work describes an experimental and numerical study to determine the corresponding detailed thermal and fluid dynamic fields developed in a burner element for domestic water heaters. A three-dimensional burner element was designed in real scale and numerical studies using Fluent code were carried out in steady-state conditions to allow continuous observations and measurements of the influence of burner element geometry and fuel-air velocity on flame characteristics, namely colour, length and stability. Air has been used as a fluid. The computational results, specifically the velocity and flame characteristics were verified with experimental data obtained in order to ensure a stable flame. In order to evaluate the power generated and the emissions of CO2 and CO associated to different burner element geometries, some experiments were performed using single burner elements with a stainless steel prismatic tank covered with thermal insulation to minimize heat losses.