A water heater includes a sealed combustion chamber and one or more fans for raising pressure in the combustion chamber to increase efficiency of the water heater. For example, the number of peaks in the T-wave, the area under the peaks, the number of points of inflection, and the slope of the T-wave can be used to detect ventricular dyssynchrony and evaluate its severity. The process further comprises the step of providing a bag filled with fibrous material.