Depending on what the model you have, you may want to flush your Gas-based water heater every 1 to 3 years. At night before doing a flush, turn the Thermostat setting of the water heater from HOT to VAC (“Vacation”) so the water won’t be heated too much.
The steps to flush the water heater usually are:
1, Turn off the gas valve.
2, Open nearby hot water faucet (usually in garage; and better also to open another one in the bathroom).
3, Close cold water inlet to the water heater.
4, Connect the garden hose to the drain valve.
5, Open the drain valve to drain the tank (turn on cold water a few seconds if the drain too slow).
6, Turn on the cold valve to flush (multiple times) after all water tank drained (see if the water is clear w/o sediment).
7, Turn off the drain valve and disconnect the garden hose if all the sediments are flushed out.
8, Open the cold valve to refill the tank when keeping one hot faucet (such as in garage) open until only water comes out from it.
9, Restart the water heater with Pilot:
9a) Turn on the gas valve.
9b) Turn Thermostat/Gas Control/Temperature Knob to PILOT from VAC (see Figure 1).
9c) Click Igniter Button while pressing the Knob (which is pointing to PILOT).
9d) Repeat 9c) until Status Light flashing (one flash indicates normal operation).
9e) Turn Thermostat setting onto HOT.
10, Put a sticker to the heater to indicate the date when it was flushed.
Figure 1, Thermostat (with Marks to indicate those positions)
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