How to Drain a Water Heater

If you own a home chances are you never give the water heater a
second thought — until it stops working. We often are asked by our
customers if it is necessary to drain a water heater. If so, how often is it
necessary. Is it a required maintenance item?

The short answer is it can't hurt (the water heater that is. Read the word
of caution below). It is often said that draining sediment off the bottom of
a water heater can extend the life of the tank. However, as we sit here
we do not know of any studies that have proved or disproved this idea.

What we do know is a water heater tank can at times contain sediment.
We had a customer who was not getting an ample supply of hot water.
Over the course of a few years the amount of hot water had diminished
from about 30-40 minutes of continuous hot water reduced to less than
10 minutes. The heating burner was fine and the thermostat worked with
WARNING: A word of caution before you attempt to drain a water
Water heaters may have water temperatures up to the boiling
point of 212 degrees F at sea level. At higher elevations (uphill) the
boiling point of water decreases thereby increasing the risk of injury to
the careless handler.  A water heater has a safety feature called a T&P
(temperature and pressure) release valve. In an overheating situation
this valve is designed to open and relieve pressure from within the water
heater--however there are times that a valve can become stuck and fails
to open. The reason for this can reside in a defective valve (rare) or
more likely one that has become defective due to the corrosive actions
of acidic water (more common). In any event it is advisable to open a hot
water valve (kitchen or bath faucet) in advance of the boiler drain on the
bottom of the water heater.  
no problem. When we drained the tank we discovered almost 2 gallons of thick syrupy sediment from the bottom of the tank.
All that sediment was acting as a heat sink and absorbing the heat from the burner. So, one could argue in this
circumstance the life of the heater had been extended. But it doesn't answer the question if sediment on the bottom of a
water heater will shorten the life of the tank itself.
Cold water intake valve for water heater.
If the water heater is electric turn off the breaker at the box. It is
important to not omit this step for the element can crack if heated with
no water. If any other fuel (gas, propane) locate the gas thermostat on
the heater and turn the knob to "PILOT" mode. It is the button on top.

STEP #2 Turn off  cold water supply. The valve will be on the cold side
of the water heater (the heater is marked on top with a large C at the
inlet). Turn the valve clockwise to close. In order to get a flow of water at
the bottom of the tank a source of air is needed to release the vacuum.
This is done by simply opening a hot water valve (any sink faucet will do.

Locate the drain on the bottom of the water heater. If a floor drain is
nearby the water may flow to the drain. Otherwise a garden hose is
attached to the drain and routed to the nearest drain. If a drain is not
available a small bucket can be used to gather water, or the hose can
be removed to the out of doors.
Cold Water Intake Valve
Drain valve  at the  bottom of typical
water heater
Once the drainage requirements have been satisfied as outlined above you can
then go about the draining process. How much water you drain depends on the
quality of the water coming out. The right amount is determined when the water
runs clear, free of debris and discoloration.
NOTE: If you utilize a garden hose that
was left out of doors in the middle of winter there may be frozen pockets of water
which will prevent water flow through the hose.

The T&P valve is usually mounted on the side of the tank. It may be on top of the
tank or on the water lines leading from the tank. It is a good idea to open the valve
to clean it out. Very often the water will come out with sediment in an orange-rusty
color. It only takes a few seconds to drain the valve.

Close the drain valve. Close the open hot water valve. Open the cold water supply
to the water heater.
Typical T&P Valve
Gas thermostat
and shut off.
For more home improvement tips visit our site Housecalls Home Services or visit the blog.
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Express Water Heater 2012

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