Noise characteristic analysis and noise reduction for gas water heater

Noise generated by gas water heater affects residents' comfort seriously. In order to understand the characteristics of water heater noise and to find its problems and propose a specific noise reduction scheme, the noise of a certain type of water heater has been tested in the semi-anechoic chamber. The noise characteristics of the prototype are obtained, and a scheme for noise reduction by adopting air intake from the top and increasing silencer shroud is presented in this paper. It is found that the average sound powers of the prototype in maximum and normal loads are 61.5 dB(A) and 58.3 dB(A). In addition, electromagnetic noise, fan noise, combustion system noise and the noise generated by cavity resonance are interacted with each other in the cavity of water heater to form a series of peak frequencies. The effect of noise reduction is obvious by intake from the top instead of the back, which causes the average acoustic powers being declined by 5.6 dB(A) and 4.7 dB(A) under maximum and normal loads respectively. Meanwhile, the drop of sound pressure level in low and middle frequency bands is obvious, and a certain extent of drop of sound pressure level at high frequency can be found. Increasing silencer shroud can reduce high-frequency noise, but noise reduction effect is less obvious due to small circulation area and big resistance.