Hydrogen Gas (Flammable) - State Water Heaters 100 Series Instruction Manual

hydroGen Gas (flaMMaBle)

Hydrogen gas can be produced in a hot water system served
by this heater that has not been used for a long period
of time (generally two weeks or more). Hydrogen gas is
extremely flammable. To reduce the risk of injury under these
conditions, it is recommended that the hot water faucet be
opened for several minutes at the kitchen sink before using
any electrical appliance connected to the hot water system. If
hydrogen is present there will probably be an unusual sound
such as air escaping through the pipe as the water begins to
flow. THERE SHOULD BE NO SMOKING OR OPEN FLAME
NEAR THE FAUCET AT THE TIME IT IS OPEN.
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