Understanding How Your Hot Water Heater Works

You may not think much about your hot water heater, and it’s easy to see why. All you have to do is turn on the tap and the water makes its way to you. In reality, the process isn’t so simple. Your hot water heater goes through an intricate process whenever you want to wash your hands or run a bath. Here’s the inside scoop on how your hot water heater works.

The mechanics of a hot water heater

As complicated as it may seem, your hot water heater is not impossible to understand. Here’s an overview of the main parts that keep your hot water heater up and running:

Tank

The largest component of your hot water heater is the tank. The tank of a hot water heater is a large outer shell. You can find it located in a garage, closet, or otherwise away from the main living area. The average tank holds between 40 and 60 gallons of water. Tanks use insulating material, such as poly urethane foam, to heat water efficiently.

There are two main types of tanks: Gas, otherwise known as fuel-fired, and electric. 60% of the homes in the U.S. use gas heaters, while the remaining 40% use electric or solar powered heaters. While a gas tank has a vent at the top to remove exhaust gas, an electric tank has a cable that connects the heater to the home’s electric panel. Gas heaters are generally less energy-efficient than electric heaters, but they have a much faster recovery rate. This makes them a convenient option for larger families who need large amounts of hot water in shorter periods of time, and for households with an existing gas line.

Tankless water heaters, otherwise known as “on demand” water heaters, are an alternative for homeowners who don’t have room for a large tank. Because they heat water on-demand, tankless water heaters work faster than traditional heaters.

Dip tube

This tube, located at the top of the tank, serves as the entry point for water as it flows into the tank. The water then travels to the bottom of the tank, to the area known as the combustion chamber, where the heating process begins.

Dip tubes generally last as long as the hot water heater they’re attached to, and aren’t prone to problems. If there is a crack or break in the dip tube, cold water entering the tank can cool down the hot water that’s about to exit the tank. This results in lukewarm water flowing through your pipes when you want hot water. A plumber can identify any problems with a dip tube during a water heater inspection.

Thermostat

Just like the thermostat in your home allows you to adjust a room’s temperature, your hot water heater’s thermostat controls the temperature inside the tank. Many manufactures set the thermostat to 140 degrees Fahrenheit by default. For most households, lowering the temperature to 120 degrees Fahrenheit produces enough hot water. This can also lower energy bills, and extend the lifespan of the heater.

Pressure relief valve

A pressure relief valve is a safety measure that keeps the pressure inside the tank from exceeding around 50 to 100 pounds per square inch. If the pressure becomes dangerously high, the valve opens to release pressure buildup and prevent a dangerous explosion. Mineral salt, rust, and corrosion can all block the valve from draining. If the valve can’t relieve pressure because of blockages, the water heater is at risk of exploding. You should test your pressure relief valve to ensure water runs out of it and doesn’t seem to encounter blockages inside the tank. If you suspect a blockage is present, call a plumber right away.

Leaks are another sign of trouble when it comes to pressure relief valves. If you notice that the valve is leaking, you should call a plumber immediately. Leaks indicate that the valve isn’t functioning correctly, creating a dangerous scenario where the water in the tank could exceed its boiling point. This could result in scalding hot water endangering your unsuspecting family members when they turn on a faucet.

Drain valve

As the name suggests, a drain valve allows water to drain out of the tank. A drain valve is an essential part of flushing the tank of your water heater. Flushing your water heater is your best defense against the buildup of calcium, lime, and bacteria that can wreak havoc on water lines and reduce energy efficiency. Due to Arizona’s notoriously hard water, these problems are an even bigger deal. You should flush your water heater through the drain valve at least once a year.

Sacrificial anode rod

Iron, oxygen, and water are the main ingredients needed to produce rust. Since all three are present in a hot water heater, a sacrificial anode rod prevents the tank from rusting. An anode rod is made of aluminum or magnesium. Due to the chemistry of these metals, they rust faster than the metal used to build the tank. The anode rod attracts all the rust, keeping the tank itself and the water inside it safe. This is where the rod earns the name “sacrificial”, as it sacrifices itself to rust away for the sake of the water in the tank.

An anode rod typically lasts up to three years. It’s important to have your anode rod replaced before its lifespan is up. Once the rod has rusted away completely, the tank itself will begin to rust, which can cause water heater failure. Rust in the tank can also cause your water to have a vague sulfur smell and taste.

The hot water process

Now that you know the main parts of a hot water heater, you can visualize how they all work together to deliver hot water when you need it.

First, water travels through your home’s water lines and then enters the tank through the drip tube. Once the water reaches the bottom of the tank, the heating mechanism turns on and heats the water until it reaches the temperature on the thermostat. As it heats up, the water rises to the top of the tank and into the heat-out pipe. From the heat-out pipe, the water enters your home en route to whichever appliance or fixture needs it. The pressure relief valve maintains a steady pressure inside the tank while all this is going on, to protect your heater from an explosion.

This process is a little different for tankless water heaters. The main difference is that, as the name suggests, there’s no water storage tank involved. When you turn on the hot water tap, the incoming water circulates through an activated heating element, which heats the water to the designated temperature. Once the tap is turned off, the heater senses that the flow of water has stopped, and shuts off the heating element.

Common water heater problems

When everything’s going smoothly, you likely pay your water heater no mind. But, when things go wrong, suddenly it’s front and center. Here are a few common problems that can impact the normal water heating process.

No hot water or not enough hot water

If your water heater isn’t producing any hot water, check to make sure its circuit breaker hasn’t tripped. If it has, all you have to do is switch it back on from your home’s main circuit panel. If not, then the problem may be a failing heating element. If your water is producing hot water, but there isn’t enough to meet your household’s demands, then your heater may also be undersized or there is another underlying issue.

If upgrading to a larger capacity water heater isn’t in your budget, you can make the most of an undersized one. Try strategically limiting the length of your showers and spreading out water-intensive chores, like washing dishes and doing laundry, to different times of the day. Or, install energy-efficient low flow showerheads and faucets to reduce the amount of water you use in the first place.

Water temperature is too hot

While everyone likes a nice warm shower, a scalding one is far less pleasant, and much more dangerous. The first thing to check if your water is too hot is the thermostat on your water heater. Turning the thermostat to 120 degrees or lower is far more efficient, and far less likely to produce dangerously hot water.

If turning down the thermostat has no effect, the thermostat may be malfunctioning. There’s no standard process of replacing a malfunctioning thermostat. The exact steps will differ depending on if you have a gas or electric heater. For best results, contact a plumber.

Water heater leaking

Whether they come from the top of the tank or the bottom of the tank, leaks of all sizes can cause major damage to your flooring and walls. Common causes of leaks include:

  • Poor maintenance
  • Improper installation
  • Age of the water heater
  • High tank pressure
  • A loose drain valve

No matter what’s causing your water heater to leak, you’ll want to act fast and work with a plumber to find a solution. To prevent leaks from recurring in the future, keep a regular maintenance schedule to make sure no small problems go unnoticed.

Tank making noises

What’s that noise? Popping, banging, knocking, or hissing coming from your water heater tank may be due to scale build-up on heating elements. Or, sediment build-up in the bottom of the tank could be to blame. In any case, flushing the tank is the best thing to do.

Rust colored water

Dirty or rusty water often means that there’s corrosion occurring on the anode rod or the tank itself. Corrosion can be serious, and if left untreated, you could end up with leaks. Flushing the tank of your water heater is a good place to start. If that doesn’t work, call a plumber to investigate if you’ll need to replace pipes, parts, or the heater in general.

Trust Chas Roberts as your water heating experts

With over 75 years of experience, there’s no water heater problem we haven’t seen before. Whether you’re disappointed by lukewarm showers or can’t figure out why your heater keeps breaking down, contact us for the answer.