PLUMBING QUESTIONS, ANSWERED

THE HOMEOWNER’S PLUMBING GUIDE

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  Why Is My Water Heater Making Rumbling Noises?
  Your water heater is making rumbling noises because of a thick sediment layer at the bottom of the tank, essentially a deeper version of the popping problem. When the burner fires beneath heavy scale, large volumes of trapped water boil simultaneously and shake the entire tank, producing a sound like distant thunder rolling through the house. The vibration stresses the glass lining and can accelerate corrosion of the steel underneath. Begin by shutting off the heat source, connecting a garden hose to the drain valve, and flushing until the water runs completely clear. If flushing produces little debris, check whether the thermostat is set too high or the tank is oversized for actual demand, since both conditions encourage rapid scaling. Inspect the anode rod during the same service visit. Rumbling that continues after a thorough flush suggests the tank is nearing the end of its life.
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  Why Is My Gas Water Heater Not Igniting?
  Your gas water heater is not igniting for a reason somewhere along the fuel or ignition path, so work through it methodically. Confirm the gas supply valve is fully open and that other gas appliances in the home still work, which quickly rules out a utility outage or an empty propane tank. Check that the control knob is set to the on position rather than pilot or off. On modern units with electronic ignition, a dead igniter, a failed piezo striker, or a tripped thermal cutoff switch will prevent startup, and the status light usually blinks a diagnostic code you can match to the label. Blocked air intake screens starve the burner of oxygen and are a frequent cause on sealed-combustion models. A blocked flue, failed gas valve, or contaminated burner assembly also stops ignition entirely. Call a licensed professional for any gas component replacement.
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  Why Is My Water Heater Pilot Light Not Staying Lit?
  Your water heater pilot light is probably not staying lit because the thermocouple has weakened or drifted out of position. This small copper probe sits directly in the pilot flame and generates a tiny voltage that tells the gas valve it is safe to remain open; when the signal drops, the valve closes as a designed safety measure. Cleaning the tip with fine abrasive and confirming it sits squarely in the flame sometimes restores operation, but replacement is inexpensive and usually permanent. Other causes include a clogged pilot orifice producing a weak yellow flame, a dirty thermopile on newer models, insufficient combustion air, a blocked flue creating downdraft, a kinked pilot tube, or a failed gas control valve. Drafts from nearby doors and dryers can also blow the flame out. Gas work carries real risk, so involve a licensed technician whenever you are uncertain.
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  Why Is My Water Heater Leaking From the Top?
  Your water heater leaking from the top is usually repairable, which is genuinely good news compared with a bottom leak. The most frequent cause is a loose or corroded connection at the cold inlet or hot outlet nipple, where dissimilar metals cause galvanic corrosion over years of service. Tightening the fittings or replacing the nipples with dielectric unions solves most cases. The temperature and pressure relief valve, mounted near the top on many models, may weep because system pressure exceeds its rating or because debris prevents proper seating. Failed inlet and outlet gaskets, a cracked plastic anode rod port, or a loose expansion tank fitting also leak. On electric units, water can seep around a heating element gasket and run down the shell. Always shut off water and power, dry everything, then inspect each fitting individually under normal operating pressure.
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  Why Is My Water Heater Leaking From the Bottom?
  Your water heater leaking from the bottom usually has one of three explanations, ranging from trivial to terminal. First, the drain valve may be dripping, either because it was not fully closed after a flush or because the plastic valve body has degraded; swapping it for a brass valve is inexpensive. Second, water escaping from a fitting or the relief valve higher up can run down the tank exterior and collect at the base, so trace the path carefully before assuming the worst. Third, and most serious, the inner steel tank may have rusted through after the sacrificial anode rod was fully consumed. Tank failure produces steady seepage that worsens over days and cannot be patched or welded. Gas units may also show harmless condensation during heavy use. Persistent bottom leaks on a heater older than a decade almost always mean replacement.