Appliance innards are mysterious. We open our dishwasher but never glimpse its hard-working pump. We enjoy cool A/C air but never see the refrigerant that pulls heat from our homes. Professional technicians may peer into appliances, swapping out things we’ve never heard of, like the “dogs” (yes, these ear-shaped pieces run washing machine agitators).
But few look into a water heater’s dark, dripping interior. What lurks there? It’s a fascinating – some might say icky - mix of stuff we want and stuff we tolerate. In sum, your water heater contains mechanical components manufacturers install and a colorful brew of rust and mineral sediment that crashes the party. The older the water heater, the more it struggles to tolerate that colorful brew as it heats your water!
At its most basic, a water heater is an insulated, glass-lined drum filled with water and fitted with a heating element and thermostat. Because heat rises, the unit feeds cold water into the bottom of the tank and removes hot water from the top. Electric models have heating elements inside the tank. Gas units employ a burner and chimney system that runs up the middle of the device. Over the years, as the heater undergoes thousands of heating and cooling cycles, its interior accumulates sediment from the water: minerals (calcium carbonate in hard water, for instance) or sand from a well. Ever heard a rumbling sound from your older water heater? That’s built-up sediment popping off the unit’s floor as water warms underneath it and struggles to rise.
One of the most important things inside your water heater is the sacrificial anode rod. Made of magnesium or aluminum with a steel core, this long rod sits in the water column and helps retard inevitable corrosion by sacrificing itself. Yes, part of your water heater is designed to rust! The rod’s metal has a more active voltage – a more negative electrochemical potential - than the metal body of the water heater. The difference in potential means the anode’s metal corrodes before the structure’s metal. Think of it this way: as long as the sentry (the rod) is still standing against rust, the castle wall (your heater’s tank) is safe.
When the rod becomes too corroded – from two to five years, depending on water pH and content – the steel tank rusts next. Assessing the condition of your anode rod without an expert is tough, but no matter the age of your unit, it pays to have a professional check the health of your anode rod, the sentry that safeguards your heater.
What’s in YOUR water heater? Service America’s experts can give you a peek into this vital home appliance!
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