rust buildup on top of water heater, no leakage, why?

5 Answers

  • 4 weeks ago

    Galvanic corrosion. 

    Most common when iron pipes are joined to other metals without a dielectric union.

  • 4 weeks ago

    humid house allows water to condense out of the air on the cold water pipe.  it runs down onto the water heater, puddles up, and rusts there.  to end this, wrap the pipe with insulation from water heater back beyond it's edge ... condensation will then drip on the floor and evaporate  -- grampa

  • 4 weeks ago

    Hot water heaters have an inner tank that holds the water, The tank is covered in insulation and then there is an outer tank that covers the insulation and protects. This outer tank is not pressure containing. Without seeing the rust it is hard to know why it is there. A good picture would help

  • 4 weeks ago

    You're probably seeing the rust around the Sacrificial Anode. Every water heater has one. Sacrificial Anodes are highly active metals that are used to prevent a less active material surface from corroding. Sacrificial Anodes are created from a metal alloy with a more negative electrochemical potential than the other metal it will be used to protect. The sacrificial anode will be consumed in place of the metal it is protecting, which is why it is referred to as a "sacrificial" anode.  They are usually put in to the top of the water heater.  These can be replaced easily by the homeowner and in fact should be replaced regularly. 

    Turn off the water to the water heater, open a faucet in the house to release pressure. Use a large socket wrench to remove the SA. clean the hole lightly with a wire brush.  use putty or teflon tape on the new annode and insert.  Turn turn on the water flow to the water heater slowly until water comes out the faucet steadily.  Check the water heater, watch for leaks.  Correct as needed. 

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  • Droopy
    Lv 5
    4 weeks ago

    If it doesn't have a small leak then its probably just sitting where the humidity is high.  If its in a basement or crawlspace with no dehumidifier I'd say thats the issue. 

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