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Here we explain just how to drain the water out of a water heater tank. This step is necessary for several water heater maintenance and repair procedures. This series of articles describes how to inspect, operate, diagnose, and repair electric hot water heaters.

The articles at this website will answer most questions about water heaters as well as many other building plumbing system inspection or defect topics. This page contains links to in-depth articles on inspecting, testing, and repairing problems residential hot water heaters of all types, including their parts, controls, and alternative sources for hot water as well as tips for improving hot water temperature, hot water pressure, and hot water quantity.

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How to Drain a Hot Water Heater Tank

Tips On Draining the Water Heater Tank: Don't try opening the hot water tank drain valve without first noting these warnings and tips:

• The water heater heat source should be turned off and the water tank cooled down (or run hot water out through building fixtures) before attempting to drain the tank - there can be a serious scalding hazard otherwise. If someone turns on electrical power to an electric water heater that is empty, it is likely that the heater electrodes will burn up.
• You can connect a garden hose to drain the water heater tank to a suitable destination
• If it's a Sunday - you may have trouble obtaining spare parts or emergency plumbing service if a problem occurs
• Be sure to have a spare garden hose cap to install over the end of the drain valve in case it drips and won't shut off completely
• If you have trouble turning the water heater tank drain valve to open it - don't force it - if break off the valve stem you may have a leak that you cannot shut off except by turning off cold water supply to the water heater
• After opening the heater drain valve, if you forgot to turn off the cold water supply coming into the water heater, you may find that water just shoots out of the drain forever - you'll need to turn off the cold water supply to the water heater.
• You will probably need to open a nearby hot water tap to let air into the plumbing system and through it into the water heater tank so that water can drain out at the tank's bottom. We don't recommend opening the pressure/temperature relief valve for this purpose as you may find that the TP valve won't shut successfully afterwards.

More details about draining and cleaning a hot water tank, including the removal of mineral or lime deposits and silt, are provided at Water Heater Noises.

If plastic water piping is installed, such as polybutylene water supply piping, it should be at least 18" from the water heater.

Water heater vacuum relief valves are required at water heaters in some communities, to protect against collapse of the water storage tank and to prevent backup of hot water into the cold water piping should cold water pressure drop. Here is Carson Dunlop's sketch of a vacuum relief valve.

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WATER HEATERS
AGE of WATER HEATERS
ALTERNATIVE HOT WATER SOURCES
  Electric Shower Heaters
  High Efficiency Water Heaters
  Indirect-fired Water Heaters
  Instantaneous Water Heaters
  Multiple water heaters in parallel
  Multiple water heaters in series
  Range Boiler Water Heaters
  Side Arm Coil Water Heaters
  Solar Water Heaters
  Tankless Coil for Hot Water
  Tankless Water Heaters
ANODES & DIP TUBES on WATER HEATERS
ANTI SCALD VALVES
DRAIN a WATER HEATER TANK
ELECTRIC WATER HEATERS
  Identify Electric Water Heater Parts
  Electric Water Heater Checklist
  Electric Water Heater Controls List
  Water Heater Anode & Dip Tube Check
  Hot Water Temperature & Pressure Valve
  Electric Water Heater Repair Guide
  Electric Water Heater: No Hot Water
  Electric Water Heater Reset & Temp Set
  Test Electric Water Heater High Temp Cutoff
  Test Electric Water Heater Elements
  Replace Electric Water Heater Element
HOT WATER IMPROVEMENTS
HOT WATER QUANTITY IMPROVEMENT
INDIRECT FIRED WATER HEATERS
ODORS IN WATER
OIL FIRED WATER HEATERS
MIXING VALVES
RANGE BOILERS
RELIEF VALVES - TP Valves on Boilers
Relief Valves - Water Heaters
SOLAR HOT WATER HEATERS
TANKLESS COILS
Water Heater Noises
WATER HEATER PROPERTIES
  Electric, Gas, Oil Water Heater Efficiency
  Water Heater Life Expectancy Comparisons
  Water Heater Operating Cost Comparisons
  Water Heater Purchase & Maintenance Costs
  Water Heater Water Quantity Comparisons
  Water Heater Recovery Speed Comparisons
  Water Heater Safety Comparisons
Water Heater Scale - De-Liming Procedures
WATER SOFTENERS

• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.

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