Because water will expand when heated, the excess pressure inside the water heater tank needs to be released. In the past, the expanding water in the tank would simply drain back out into the municipal water supply where it came from. Today, the water main is designed to prevent the backwards release of pressure, known as backflow, by employing a check valve. The check valve prevents waste water from inside the house returning to the water supply where it can contaminate the supply of fresh water.
A water heater expansion tank is another small tank that is attached to the water supply pipe of the water heater. The expansion tank is designed to handle the thermal expansion of water as it heats up in the water heater, preventing excessive water pressure. If water pressure gets to high it can damage valves in plumbing fixtures, joints in supply pipes and the water heater itself. Expanding water from the water heater flows into the expansion tank, relieving water pressure in the system.
What if my water heater doesn’t have an expansion tank?
Most homes that have a check valve on the water main do not have an expansion tank, since it wasn’t required until recently. This may or may not cause excessive pressure buildup, depending on the specific design of the plumbing in the house.
If you are noticing that washers in plumbing fixtures are deteriorating rapidly, or water is dripping from the relief valve on the water heater, it may be wise to add an expansion tank. It can be low-cost insurance against more costly damage to your home’s plumbing system.
It’s hard to imagine living in a world in which we don’t have a supply of hot water on demand.
The only time we even think about it is when our hot water heater breaks down. And that’s when we realize how important it is to the quality of life.
How can we keep these hot-water miracles performing to their fullest?
The first step is a clear understanding of the main parts of a water heater. Without that knowledge, homeowners will never know how to get the most life out of their water heaters, when to repair or replace them, or if they’re getting ripped off.
A water heater is a tank that stores, heats, and delivers hot water wherever you need it.
In addition, its tank is usually lined with steel on the inside with glass, porcelain, or cement. It is wrapped on the outside with insulation and an enamel metal jacket.
How does a hot water heater work? If you want to know all the basics, then all you really need to know are the parts of a water heater. All gas, oil, and electric water heaters have the following components in common:
As you can see, the parts in an electric heater (left) are like those in a gas heater.Tanks have 1 or 2 magnesium or aluminum anode rods inside to protect exposed steel from corrosion. They’re also called anti-corrosion or sacrificial anode rods. Tanks with longer guarantees (10+ years) often have 2 rods for extra protection.
Magnesium anode rods are best used in soft water situations. If you have hard water, then an aluminum anode rod is best for your device.
Also, a hot water heater tank can become contaminated with desulfovibrio bacteria. This bacterium thrives in hot water in the presence of magnesium.
In addition, the bacteria causes the hot water supply (not the cold water) to smell like rotten eggs. If you notice this smell, get your water tested for contamination. The solution is to chlorinate the tank and replace the magnesium anode rod(s) with an aluminum rod.
Magnesium anode rode being pulled out of a tank.You can change the anode rod that comes with your hot water heater. There are many benefits and differences between powered anode rods and traditional ones. Powered anode rods, made of titanium and equipped with a current rectifier that plugs in, are more effective than traditional sacrificial magnesium anode rods. The rectifier creates a small current in the water, which offers several benefits. It reduces the sulfur smell in your water, prevents tank corrosion, and minimizes limescale buildup.
These powered anode rods last much longer than traditional magnesium ones because they do not corrode like sacrificial rods.
The incoming water supply pipe to the hot water heater comes from a water softener or conditioning system, or from the main line.
There should be a cold water supply shut-off valve on the supply side near the water heater so the water can be off in case of repair or replacement.
Notice the shut-off valve on top of the cold water supply inlet pipe.The inlet on the top of the tank sends cold water to the bottom of the tank through a dip tube. That keeps the cold water from cooling down the hot water.
Hot water leaves the tank from the outlet at the top.
Sometimes, you’ll find that the inlet and outlet pipes are reversed. Then cold water enters right into the top of the tank because it isn’t going through a dip tube. Someone who takes a shower is going to be met by a blast of cold water.
PRO TIP: Plumbers might reverse the inlet and outlet pipes only for the sake of convenience. If they take this approach, they should also correct the situation by also moving the dip tube to the outlet.
Additional reading:All hot water heaters must be protected with a relief valve, also called a temperature-pressure relief valve (TPR or TP Valve).
The TPR lets water escape if the temperature or pressure is too high in the tank. This component is a safety measure that keeps your tank from blowing up.
It should mount on the top of the tank or on the side of the tank, within 6 inches from the top. If you find a relief valve on the hot water pipe above the tank, you probably have an older tank and should consider a replacement. This practice is no longer acceptable and is not safe.
The TPR should have a metal extension or discharge tube that extends down the side of the tank to within 6 inches of the floor. This ensures that hot water and steam don’t spray anyone nearby. The extension may not be threaded at the bottom or have a turn-off valve. This is to prevent anyone from capping or plugging the extension.
PRO TIP: Don’t try to repair a leaking relief valve. You should always replace it with a new one.
The temperature-pressure relief valve.Water heaters are designed to output water at 140 degrees and can be set to individual preferences with the thermostat. Often, a range of between 115 and 120 degrees is safer and more energy efficient.
You can adjust the thermostats on electric water heaters by using a screwdriver.
Gas water heaters have a dial or knob thermostat at the control unit.
The thermostat on a gas water heater is usually a dial or knob like the one pictured here.In short, every water heater should have a drain valve at the base of the tank. With this in mind, you should drain few gallons of water out several times a year to get rid of any sludge or sediment buildup in the tank.
A fairly typical drain valve with a hose attached. Some drain valves release water by using a turn screw.Another key point is that you measure water heater size in gallons. There is a wide range of sizes for all types of tanks. The most common are:
Surprisingly, they come in sizes that are smaller and even larger.
Some standards suggest an 80-gallon tank for a family of 4 with a clothes washer and dishwasher. However, a 40-gallon gas or oil water heater, or a 40- to 50-gallon electric water heater are typical in many homes.
As a matter of fact, it’s not uncommon to use up all the hot water from your tank. The question then becomes, “how long before I get my hot water back?”
Now that you know the basic components, here’s the next step in learning how a hot water heater works.
Make sure your tank is against an outside wall to make room for the flue. This also meets most regulations.
PRO TIP: Firstly, keep stored items away from your tank to prevent damage from any leaks or mishaps. Secondly, you should not install gas and oil water heaters in closets, bedrooms, or bathrooms. By all means, these types of fossil-fuel hot water heaters need an adequate and continuous air supply for proper combustion.
On the inside of a home, always place the water heater near an outside wall.Above all, carbon monoxide is a life-threatening byproduct of combustion and must be safely exhausted. Consequently, that’s why fossil-fueled water heaters must vent to the outdoors. This usually occurs through the chimney or directly through the wall to the outside.
Gas and oil water heaters must have a flue pipe from the tank to the chimney, requiring an upward slope of 1/4 inch for every foot of pipe. If the flue pipe is a single-wall pipe, the installation needs to be at least 6 inches away from any combustibles.
The double-walled flue should vent a minimum of 1 inch above the roof (2 inches for single wall) or higher depending on the slope of the roof.
In addition, you need to install a draft hood at the top of the tank. This will prevent carbon monoxide from going back into the home.
It’s worth checking the age of your unit before you install a new one. To know whether you need a repair or replacement, you need answers to these first:
The following article will answer those concerns. They will also tell you what you can do to maximize its life and performance.
Furthermore, here are more resources for all kinds of water heater information and instructions:
Overall, don’t hesitate to contact us here or call us at 1-Tom-Plumber (1-866-758-6237) if you need help with your hot water heater.
1-Tom-Plumber’s certified team of plumbers and drain technicians respond immediately to any emergency plumbing, drain, or water damage problem, including excavation of underground water lines and sewer main lines. Our immediate-response team is available every day and night of the year, even on holidays.
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