To be cleaned, the place to clean is mainly the combustion chamber, and the fire row. Because the water heater burning gas during the working process will produce carbon scale, carbon scale will block the combustion chamber, resulting in insufficient gas combustion, carbon monoxide can not be smoothly discharged, the lid of the water heater will burn discoloration. So the combustion chamber needs to be cleaned. As for the fire exhaust, gas or natural gas will have residue, when burning, residue will not burn, will become granular fall on the fire exhaust, over the years, after a long time may block the fire exhaust vent, resulting in fire exhaust backfire. Therefore, it is necessary to clean the water heater regularly, generally about 3 years to clean, you will find that the service life of the water heater is longer