Your Water Heater Survives by Eating a Metal Rod

Inside every tank water heater hangs a rod of magnesium or aluminum that dissolves on purpose, so the steel tank around it doesn't rust through. A 3D cutaway of a typical American gas water heater: how cold water gets in at the top but ends up at the bottom (the dip tube), why the tank stays layered, why your shower goes from hot to cold all at once, the thermocouple that shuts off the gas if the pilot goes out, the flue baffle, the sacrificial anode, the rotten-egg smell, the popping of sediment, the T&P relief valve you must never plug, and the 1990s dip tubes that crumbled. 00:00 Your water heater is eating a metal rod 00:41 The parts 01:30 Cold in at the top, out at the bottom 02:18 Where the heat comes from 03:08 Why your shower runs cold all at once 03:50 The sacrificial anode 04:56 The rotten-egg smell 05:27 Sediment: the popping sound 06:04 The T&P valve 07:03 The dip tubes that crumbled 07:38 One gallon, start to finish The heater on screen is an illustration of a typical US gas storage water heater, not one manufacturer's model. The temperature colors, the hot-layer gauge and the pressure/temperature dials are schematic. The real photos are credited under PHOTOS. This video explains how the parts work; it is not repair advice. Gas appliances and T&P valves should be serviced following the manufacturer's manual or by a qualified technician. Sources US Department of Energy, Energy Saver: Storage Water Heaters (20 to 80 gallons; hot water drawn from the top, cold enters the bottom through the dip tube; anode rod). US patent 9,228,746 (thermocouple at the pilot holds the gas valve open); US patent 6,546,897 (flue baffle and heat transfer). US patents 4,848,616 and 9,335,065 (sacrificial magnesium anodes in glass-lined tanks; hydrogen sulfide odor, magnesium vs aluminum/zinc anodes). Watts Water Technologies, Temperature and Pressure Relief Valves (150 psi / 210°F); Washington Administrative Code WAC 296-150C-1500. Supply House Times, "Settlement approved in dip tube suit" (Perfection Corp. dip tubes, Aug 1993 to Oct 1996, nearly 14 million); JLC, "Q&A: Faulty dip tubes in water heaters". US Consumer Product Safety Commission, Publication 5098, Tap Water Scalds (140°F: third-degree burn in about 5 seconds; set heaters to 120°F). PHOTOS (Wikimedia Commons): David E. Lucas, City of Columbus, via DPLA (water heater inspection, public domain); OakleyOriginals (flooded basement, CC BY 2.0); Tomwsulcer (basement gas heater, tank fittings and stripped tank, CC0); Jason Woodhead (gas valve dial, CC BY 2.0); Bautsch (magnesium anode, CC0); Czarking0 (rusty bottom plate, CC0); JovanCormac (shower head, CC BY 2.0). CC BY 2.0: https://creativecommons.org/licenses/... #waterheater #howitworks Next: why your gas furnace never lets fire touch your air:    • Your Gas Furnace Never Lets Fire Touch You...