Tank-Style Gas Water Heaters: How Do They Work? How Can You Care For Them?
Every home needs some kind of source of hot water. The majority of modern homes use the standard-style water heater that is a gas tank-kind of unit. Such models prove advantageous because they only require minimal maintenance in exchange for years of hassle-free functionality.
The Popular Choice
Granted, tankless water heaters are growing in popularity, and they only heat water when necessary. However, tank-styles are more affordable and still the number-one option most homeowners prefer.
Two Kinds
Tank-style water heaters come in two versions. The first is gas, and the second is electric. However, gas models are far more common given how much less they cost upfront and over time.
The Fundamental Operations Of Gas Water Heaters
Tank-style water heaters live up to their name. They take in cold water, heat it up, and then store it until use. Homes use hot water for numerous appliances and plumbing fixtures, including but not limited to dishwashers, washing machines, sinks, tubs, and showers.
Making Physics Work For You
Gas water heaters use the convection law of physics, based on how heat rises. In the specific application of water heaters, a supply tube constantly forces cold water into the interior of the tank. Since cold water is more dense than hot water, it drifts to the bottom inside the tank. A gas burner that is underneath the sealed tank heats the water. When the water warms up, its density goes down, meaning it rises to the top of the tank. There, a discharge pipe for hot water provides the home with hot water whenever someone in the home needs it. The discharge pipe for hot water is a lot shorter as compared to the dip tube. The reason for this is so that it can extract the highest-temperature water, which is always going to be at the top inside the tank.
Taking Charge
Most gas-powered tank water heaters have a gas regulator assembly installed on the side of the heater. This is what controls the gas burner underneath the heater, and it has a thermostat used for measuring the water temperature inside the tank. This thermostat turns the burner on or off as necessary to keep a set temperature for the water.
Another Layer Of Efficiency
There's an exhaust flue that runs through the middle of the tank. Its function is letting exhaust gases the chance to flow upwards throughout the tank before escaping through either a vent pipe or chimney. Manufacturers fit these hollow flues with spiral metal baffling able of capturing heat and releasing it into the tank's water supply. This makes the entire appliance more efficient, and less energy use means lower operating costs for homeowner utility bills.
Many Components For One Mission
The purpose of any hot water heater, tankless or otherwise, is to provide your plumbing fixtures and appliances the hot water you need for cooking, cleaning, and comfort. While the purpose is singular, there are many components involved in this creature comfort of modern civilization. Looking closely at every component of these water heaters shows just how simple yet smart tank-style gas water heaters can be.
The Water Tank
The actual tank of these water heaters has a steel outer jacket enclosing its pressure-tested storage section. High-grade steel with either a layer of plastic or vitreous glass bonded to the interior prevents rusting. The middle of the tank has that hollow exhaust flue already mention, which lets burner exhaust gases flow upwards before venting out. Most water heaters of this design have spiral metal baffling inside that flue to absorb exhaust gas heat and convey it into the water as a secondary means of heating.
A layer of insulation is in place in between the outer jacket and interior storage space. Its purpose is minimizing heat loss for even more efficiency.
Money-Saving Tip: Homeowners can also supplement water heater insulation by wrapping a fiberglass insulation tank jacket around the exterior of the water heater. Tank jackets like these are usually very affordable, as well as simple to put into place. However, it's crucial to not block the flue hat at the tank's top, nor the burner access panel.
The Tank Interior
As stated already, there are two primary components inside these tanks. One is a long dip tube bringing cold water into the tank, and the second is a shorter discharge pipe for hot water to enter a home's plumbing system. However, there are other crucial components inside the tank, too.
Glass-lined tanks have sacrificial anodes, which are metal rods inside the tank, typically made of aluminum or magnesium. Manufacturers bolt anode rods or fasten them to the tank top before the extend deep within the tank. These components draw any rust-causing ions present in the water to them, which is very useful in preventing corrosion inside the metal tank. Alternatively, certain models don't have dedicated anode rods, but rather accomplish the same thing with an aluminum- or magnesium-coated outlet pipe.
DIY Maintenance: Any homeowner that has smelly or discolored hot water coming out of their faucets might be seeing symptoms of an anode rod that's all used up. Fortunately, anode rod replacement is a relatively simply DIY task. Anything you can do yourself saves you paying the labor charges professionals would charge.
Supply And Discharge Pipes
Two water pipes are fitted at the tank's top surface. One is a supply pipe bringing in the cold water, while the other is a discharge pipe for the outgoing hot water.
Supply Pipe For Cold Water: A shutoff valve controls the supply line of cold water. Knowing where this is located is essential so that you can close it whenever it is time for maintenance or repairs.
Deactivating the supply of cold water basically terminates the entire flow of water, since its the constant pressure of cold water coming into the tank that means the hot water is also flowing out. Many but not all models have blue handles for their cold water supply shutoff valves.
Discharge Pipe For Hot Water: This is the important end of your hot water heater. This pipe is the one supplying your home's needs for hot water.
Discharge pipes for hot water sometimes also have their own shutoff valves, typically marked with red handles in contrast to the blue for cold water coming in.
Gas Regulator/Burner Assembly
Gas water heaters use either propane or natural gas as a fuel source. In both cases, the fuel heats the water after coming through its own pipe. These gas pipes are often made using copper tubing or black piping. It's also crucial you know where to find your gas shutoff valve on this pipe, so that you can disable the gas supply for repairs, maintenance, and emergencies.
The gas line eventually feeds into the gas regulator, and that regulator includes the water heater thermostat. This particular valve additionally supplies gas to the pilot light, via a smaller auxiliary tube. The pilot light is there to light up the burner anytime the thermostat and regulator valve dictate it.
After the gas regulator, the fuel flows into the gas burner assembly. This is something that you can access via a metal panel. It's on the bottom of the exterior casing of the water heater. This assembly has both the gas burner and pilot light. Adjustments to both are crucial to appropriate and energy-efficient water heater functionality.
Safety Tip: Your ideal gas flames are going to be roughly 1/2 inches tall. They'll also have blue tips, as yellow flames can be indications of improper air mixtures or dirty burner jets.
The pilot light also has a crucial component called the thermocouple. This small valve turns heat into an electrical impulse. Newer water heaters might label this component as a flame sensor. Whichever name it is called, flame sensors and thermocouples are critical safety features, since they detect the active presence of a pilot flame. In doing so, they can prevent gas from going to the burner where there isn't any pilot flame there for ignition.
Save Money Again: Flame sensor or thermocouple replacement is another relatively simple DIY task you should be able to handle. If yours isn't working right, don't waste money on higher utility bills or even potential damage to your home by delaying this particular repair.
The Exhaust Flue
A water heater's exhaust flue is a hollow cylinder that goes through the middle of the tank. It has two purposes. The first is exhausting combustion gases coming from the burner, while the second is providing heat to the tank water as a kind of heat exchanger. This flue has to be safely exhausted to outside the home, and flue construction is highly regulated by particular code requirements and regulations.
T&P Valve
T&P stands for temperature and pressure-relief. This combination valve/discharge pipe is a crucial safety component of any hot water heater. If you know about your car's radiator cap, then you are already familiar with the general concept. The whole point of this valve is to relieve any pressure or temperature inside the tank that's getting towards the design limits of the water heater tank.
Testing The T&P Valve
Find this valve at the top of your tank, where it is usually threaded right into the top of the tank. If you want to test this valve, just slightly lift up its handle. You should see water discharging out of the tank via the overflow pipe. If your T&P valve isn't working right, you need to replace it.
The Drain Valve
If you're lucky, or you are diligent about maintenance, then your hot water tank is going to last you a long time. However, the longer it runs, the more it can have sediment accumulation inside the tank, esepcially at the bottom. Water heaters that are filled with sediment don't heat as efficiently as they once did. You might hear this with your ears, as moisture-saturated sediments might cause gurgling or bubbling sounds when they boil.
Use your tank drain valve to routinely drain your tank. Tank flushes aren't especially difficult, and they remove sediments and prevent the complications that sediments cause.
The Steps Involved With A Tank Flush
The first step in a tank flush is turning your gas pilot control valve towards its 'pilot' setting. Next, disable the supply of cold water coming into the water heater. Third, open up your closest hot water faucet in your home. Fourth, attach your garden hose to the water tank's drain valve. Fifth, place the hose's open end into a utility sink or a floor drain.
Open your tank's drain valve, and then let all the water in the tank to drain out. When the sediments flush out, you're likely going to see discoloration in the water draining out. In serious cases, it might be necessary to refill your tank using fresh water before doing a second flush to get rid of more sediments.
When your tank is empty, you can refill the tank by shutting off the drain valve and then opening up the supply valve for the cold water. Then, turn your gas control valve back to the 'On' positions, and verify that your gas burner has ignited.
In Summary
Water heaters are designed to provide residential homes hot water for washing hands, dishes, clothes, and even your whole body. Tankless models are growing in their popularity, given their smaller footprint, but if you're like most homeowners, you still want a tank-style model, either powered by gas or electricity.
Gas-powered models, as discussed throughout this content, provide a reliable and steady supply of hot water available to you and your family every time you turn on a faucet, run your dishwasher, or start the washing machine. Tank-style gas water heaters are built not just for reliability, but also energy-efficiency, saving you money on your utility costs over the lifespan of the unit.
Use the tips and knowledge presented here to know when something might be wrong with your water heater, as well as how to fix it, so you can save even more money over time.