The Anatomy of Gas-fired Storage Tank Water Heaters

The Anatomy of Gas-fired Storage Tank Water Heaters
October 18, 2012 Lorelie

In the past, before the invention of the water heater, if people needed to take a hot bath, they had to boil water in a pot, kettle, or cauldron and mix the boiled water with cold water to get the right temperature suitable for a hot bath.  There are some that even go to lengths as to heating large drums filled with water and submerging themselves inside the drum when the water reaches the right temperature.  Such is the predicament of the old days when they needed hot water to get a hot bath.

Thankfully, these days, we no longer have to undergo such difficult situation just to get a hot bath.  In fact, with the advancement of technology, we now have several types of water heating units that help us to choose which is more suitable for us.  You will also find that these water heaters can be powered gas, electric, and even solar.  Among the many types of water heaters, one of the most popular is the gas-fired storage tank water heater.  This is likely because gas is much cheaper to use than electricity and that gas also heats water much faster.

Gas-fired storage tank water heaters have gone through a lot of development and innovation since their inception. This would mostly include insulation, temperature automation, and material used.  However, the basic principle on how a gas-fired storage tank water heater works remains the same – heat water inside a storage tank using a controlled blaze at the bottom of the tank.  The list below shows the anatomy of a gas-fired storage tank water heater.

The standard storage tank water heater is the most common type of water heater as with just very little maintenance, can provide any household with years of trouble-free operation.  A gas-fired storage tank water heater works by using convection, a simple law of physics that makes the heated water rises.  The cold water is supplied inside the tank, specifically at the bottom, through the use of the dip tube.  Following the laws of physics, the cold water will settle at the bottom and will be heated by the gas burner at the bottom of the tank.  Once the water heats up, it will rise towards the top, which can be drawn out via the hot water discharge pipe.  If you open up the tank, you will find that inside of it, the cold water pipe is much longer than the hot water pipe.  This helps ensure that only the hottest water gets drawn out from the tank.

Components of a Gas-fired Storage Tank Water Heater

Cold Water Supplycold water is supplied inside the tank using the cold water supply line, which is then controlled by the shutoff valve.  This shutoff valve allows you to manually stop the supply of water going inside the tank, something which can be very handy when performing maintenance.

Hot Water Discharge – this is the tube where hot water gets drawn out from the tank.  It is the tube that supplies your household with its hot water supply.

Tank Construction – the tank jacket is made of steel and it encloses a water storage tank that is pressure tested.  In between the storage tank and the exterior tank jacket is insulation material that helps to reduce any heat loss during the heating of water and during standby.  Despite the already built-in insulation, it is always a good idea to place additional insulation such as a fiberglass insulation tank jacket on the exterior of the unit itself.  This is both inexpensive and easy to install.

The inside of the tank will contain a dip tube where the supply of cold water enters the tank.  Following the laws of physics, cold air, or for this instance cold water, is denser than hot water.  This makes it heavy making it settle at the bottom part of the tank.  However, as the cold water is heated by the gas burners, it becomes less dense ergo lighter, which is why it rises to the water level line.

With glass-lined storage tanks, you will also find a metal rod called the sacrificial anode, which is usually made from magnesium or aluminum.  This anode rod serves the purpose of drawing corrosion unto itself instead of the tank.  This helps to further extend the life of the steel storage tank.  Plastic-lined storage tanks have no need for an anode rod.

Gas Burner Control Module – natural gas or propane is used to supply fuel for the unit.  The gas supply line has its own shutoff valve which allows you to manually stop the supply of gas into the unit.  The gas line goes into a gas burner control module which acts as thermostat as well as ignition control for the pilot light.  After the control module, the gas line then flows to the gas burner.  Proper adjustment of the burner and the pilot light helps to create energy efficient operation.  It is also important to make sure that the flames have blue tips so as not to create soot on the tank – something which can deteriorate the tank prematurely when left for prolonged periods.

Exhaust Flue – this is where combust gasses passes to be properly vented outside the home.  It also acts as a sort of heat exchanger helping to heat water in the process.

Temperature and Pressure Relief Valve – this is one of the safety feature built into water heaters.  Should there be a buildup of excessive temperature or pressure inside the tank, this safety mechanism helps to discharge it out through the overflow or discharge pipe.  It is important to make sure that these safety mechanisms always work properly.  To test them, lift the valve up slightly and you should notice hot water being discharged out of the overflow pipe.

Drain Valve – when performing maintenance, particularly when flushing the tank due to sediment buildup, draining the tank of water from the drain valve helps to remove and flush out some of the sediments that have built up through the months of use.

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