Water Heating

Tank and tankless water heaters — sizing, gas and electric, recirculation, venting and the common failures and fixes.

12 guides

• Anode Rods and How They Decide Tank Life
  Why the sacrificial anode rod is what actually determines how long a glass-lined tank lasts, how to check and replace it, the magnesium-vs-aluminum-vs-powered choice, and how to fix the rotten-egg smell that comes from the anode reacting with the water.
• Electric Tank Water Heater: Elements, Thermostats, and How to Test Them
  How a dual-element electric water heater stages its upper and lower elements, what the high-limit ECO does, and the exact meter steps to find a bad element or thermostat — resistance values, the non-simultaneous logic, and the common failure patterns.
• Expansion Tanks and Thermal Expansion on the Water Side
  Why heating water in a closed plumbing system spikes the pressure, how a thermal-expansion tank absorbs it, how to size and precharge the tank to incoming static pressure, and how to recognize a failed tank — the real fix for a T&P valve that drips after every heating cycle.
• Gas Tank Water Heater Anatomy and Firing Sequence
  The parts of a standard atmospheric gas storage water heater and the order it fires in on a call for heat — from the thermostat in the gas control valve through the burner, draft hood, and recovery — so you can find where a no-hot-water unit quit.
• Heat-Pump (Hybrid) Water Heaters: How They Work and What Breaks
  How a hybrid heat-pump water heater pulls heat from the air to make hot water, the operating modes (heat pump, hybrid, electric, vacation), why it needs room air and a condensate drain, and the maintenance and diagnostic points HVAC techs already know how to handle.
• Hot Water Recirculation Systems
  How recirculation systems get hot water to the tap instantly — dedicated-return loops with a pump and aquastat vs. retrofit crossover-valve systems that use the cold line as the return — plus controls, energy tradeoffs, and the common failures.
• No Hot Water: Diagnosing a Gas Tank Water Heater
  A systematic no-hot-water diagnostic for a gas storage water heater — confirm the complaint, check gas/pilot, read the status light, work the thermocouple and gas control, and split lukewarm-vs-stone-cold so you fix the right thing the first time.
• No Hot Water: Diagnosing an Electric Tank Water Heater
  A systematic no-hot-water tree for an electric tank — verify power, reset the ECO and find why it tripped, then meter the elements and thermostats using the non-simultaneous logic, and use the lukewarm-vs-stone-cold split to point at the right element.
• Sizing a Water Heater: First-Hour Rating vs. Peak Demand
  How to size a storage water heater by peak-hour demand against its first-hour rating (not just tank gallons), how recovery and temperature rise factor in, and how tankless sizing differs by GPM at the design temperature rise.
• Tankless Water Heater Operation, Maintenance, and Descaling
  How a gas tankless (on-demand) heater senses flow and modulates to hold an outlet temperature, why scale is its number-one enemy, and the step-by-step descaling flush — plus the flow, temperature-rise, and cold-water-sandwich gotchas techs hit.
• The T&P Relief Valve and Water Heater Safety
  What the temperature-and-pressure relief valve protects against (a tank turning into a steam bomb), how it's rated and piped, why it weeps or dumps, and the discharge-line rules — the single most important safety device on any water heater.
• Water Heater Venting: Atmospheric, Power-Vent, and Direct-Vent
  The three ways a gas water heater gets rid of flue gas — natural-draft atmospheric, fan-assisted power-vent, and sealed-combustion direct-vent — how each drafts and gets combustion air, and the backdraft and common-venting problems that make this a safety topic.

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