What should I do if my hot water system has not been used for 2 weeks or more before running the washer?

Before using the washing machine, turn on all hot water faucets and let the water flow from each for several minutes to release any accumulated hydrogen gas. This is necessary because hydrogen gas, which is explosive, may have built up in the system, and since the gas is flammable, you should not smoke or use an open flame during this process.