Introduction: Hot Water Tank or Heater Basics

You might already know that down in the guts of your house, among the furnace, the sump pump, and your pipes that lead up into the walls, floors, and ceilings, there’s a machine in your utility room that heats water and pumps it through the house as you need it.

Not too long ago, people had to use pots to heat water over a fire or on a stove for cooking, baths, and washing, but as better technology became widely available, we created the beginnings of modern-day hot water heaters.

The first version was a huge, metal tank that was filled with cold water and heated with elements using oil, electricity, or gas. This hot water tank was wrapped with insulation to help keep the water at a steady temperature, ready for use as needed.

It wasn’t the most efficient system because water cools quickly, so the heating elements had to be on just about all the time.

Now, we have a variety of ways that we heat water for household or commercial use, and in this guide, we’ll tell you everything you need to know about them.

Types of Hot Water Heaters

There are a lot of different types of hot water heaters, and choosing the right one can be confusing if you’re not a plumbing professional. In this section, we’ll tell you about some of the best kinds to have for residential and commercial use.

Top 4 Hot Water Tanks Types for Residential Use

Electric Tank-Type Hot Water Tank

An electric tank-type hot water heater is exactly what it sounds like. It is basically a tank that holds water with elements that heat water that are powered by electricity.

Gas Powered Tank-Type Hot Water Tank

Another version of the tank-type hot water heater is one that is powered by natural gas. It has the same look as the electric version but has a few more components, like a pilot light, burners, and gas-specific safety features.

Whole House Tankless Hot Water Tank

Tankless water heaters are the newer, sleeker kind of hot water heaters that work a little differently than traditional tank-style water heaters. They don’t store water at all. Instead, when water is needed, it flows through this machine, gets heated instantly by a gas burner or electric element, and is sent out to where it is wanted.

Point of Use Tankless Hot Water Tank

The smaller version of the tankless hot water heater is called a Point of Use or Mini Tankless Water Heater. It’s so small that it can fit in a cupboard or under the kitchen sink, which can be ideal if you live in an apartment where the central water system doesn’t get the water hot enough for you. They’re also great for getting you hot water FAST! With these little guys, you don’t have to wait for your shower to warm up because it gives you hot water almost instantly.

Since they are small, they are only intended to serve one tap, faucet, or shower.

Top 3 Hot Water Heaters for Commercial Use

Boiler Systems

A boiler is a pressure vessel that creates heat and steam that is used to heat water, provide energy, or heat entire buildings. They can also be used in industrial applications.

Commercial Natural Draft

Also known as Condensing Water Heaters, these are high-efficiency water heaters powered by natural gas that capture the residual heat from the combustion process to preheat incoming cold water instead of venting it directly outside.

Commercial Power Vented

Commercial power-vented water heaters are designed to have high efficiency and deliver a constant flow of hot water on demand. If your water heater is located deep inside the building, it’s smart to get a hot water heater with power venting (a blower or fan) to blow the exhaust a long way to the outside. This type of heater can be necessary if there isn’t access to a vertical vent or chimney for the exhaust fumes to escape from.

Components of Tank-Type Hot Water Heaters

These next few sections aren’t intended to be comprehensive breakdowns of all the parts of each kind of hot water heater. They are basic overviews of the main parts of each type to give you an idea of how each one works.

Knowing the components will help you to troubleshoot and provide maintenance on your hot water heater and give you an understanding of how each one works.

The Cold Water Inlet and Shut-Off Valve

Cold water is brought into the tank via a supply line that is controlled by a shut-off valve. Knowing where your shut-off valve is can be crucial if you ever need to turn the hot water off right at the source. If you’re doing dishwasher, washing machine maintenance, or the hot water heater itself, this is one of the first things you should do.

The Hot Water Discharge Pipe

Put simply, this is the pipe that hot water comes out of. When someone turns on the shower or an appliance demands it, hot water comes out of the hot water discharge pipe and flows to the person or machine that needs it.

The Tank Itself

Hot water tanks are actually made up of three layers. The outside layer or ‘jacket’ is made of steel and inside it is a pressure-tested water tank surrounded by a layer of fibreglass insulation. To make hot water tanks retain more heat, some people will add another layer of insulation on the outside of the tank, for a total of four layers.

[Tweet “The average hot water tank is 40-50 gallons. Go tankless if you need more. #plumbing #tips”]

The Dip Tube

‘Dip Tube’ kind of sounds like the name of a fun waterslide, but it’s really just a plastic pipe that brings water from the cold water inlet down to the bottom of the tank where it can be heated. When the water warms up, it rises to the top, ready to flow out of the hot water discharge pipe.

The Anode Rod

An anode rod is an anti-corrosion device. As the name suggests, it is a rod-shaped piece of aluminum, zinc, and/or magnesium pipe that hangs from the top of the tank.

The reason it’s there is because when metal and water come into contact with each other, the metal will corrode or wear down. Since the water tank is made of steel, the idea is that corrosion will feed on the anode rod rather than the steel tank because it is an easier target. That’s probably why it’s also known as the sacrificial rod.

Plastic or glass-lined tanks don’t have anode rods.

Heater Drain Valve

The drain valve looks kind of like a faucet and can be opened to flush out particles of sediment or to drain the tank if you need to.


Like the thermostat you use to control the air temperature in your home, your hot water heater has a thermostat. To adjust the temperature of your water, (usually, it is kept around 120 degrees) you use the knob on the side of the tank, near the bottom.

If your water heater has two thermostat knobs, make sure that they are set to the same temperature.

For a full explanation of hot water heater thermostats, watch the video below.

Temperature and Pressure Relief Valve

Another safety feature of hot water heaters is the temperature/pressure relief valve. When the water in the tank gets too hot or when there is too much pressure in the tank, this valve will automatically release water or steam.

Components Specific to Gas-Powered Hot Water Heaters

Venting System

The combustion from the used gas has to go somewhere, so a venting system needs to be in place. This consists of ducts that vent the combustion outside.

Pilot Light

Like all the old furnaces, gas-powered hot water heaters also have a pilot light that is always lit. It is used to fire up the burner.


The thermocouple looks like a small piece of copper wire and it works by sending a small electric current to the gas valve when the pilot is lit and sending gas to the burner when the thermostat needs it.

Burner/Pilot Orifice

This is a small piece of metal that controls the flow of gas to the pilot. It looks like a teeny tiny brass cup and you’ll find it at the end of the pilot supply line.

Gas Control Valve

This is a very important piece of equipment for a gas-powered hot water heater. It works with the pilot light and the thermostat to control the temperature of the water.

Components Specific to Electric Hot Water Heaters


The element in your electric hot water heater functions just like the elements on your kitchen stove. Usually, your hot water heater will have a couple of elements, one at the top and another at the bottom.

Thermal Cutoff/High-Temperature Cutoff Switch

In the event that an electric hot water tank malfunctions or the water inside it get too hot, there is a safety device called the high-temperature cutoff switch that will shut down the heater and the switch will need to be reset.

Components of Tankless Hot Water Heaters

Tankless hot water heaters differ from ones with tanks in that they don’t store water. Rather, they heat up water as it’s needed and pipe it directly to the faucet or appliance that called for the hot water.

They do have some similar components, like incoming and outgoing water valves, heating elements or burners, thermostats, and temperature-sensing equipment. The main difference is that tankless hot water heaters use something called a heat exchanger to transfer heat to the water flowing through it.

Below we describe the major components of tankless hot water heaters.

Temperature Control Knob or Digital Temperature Controller

To control the temperature of the water coming out of the hot water heater, there is a temperature control knob or a digital temperature controller on the control module that you set to the temperature you want your hot water to be.

Control Module

The control module is the brain of the tankless hot water heater. You input the temperature you want your water to be heated to, and the control module works with sensors in the unit to determine when and how much power to send to the heating element or burner.

Cold Water Valve

The water valve in a tankless hot water heater is where cold water enters the unit.

Flow Sensor

Tankless water heaters are activated when water flows into them, which happens when you turn on a faucet. The flow sensor detects water flowing through the water valve and tells the controller that water is coming in.

Temperature Sensor

There are temperature sensors in tankless water heaters that sense the incoming and outgoing water temperatures. These sensors triggers the heating process by sending the information to the control module which determines the amount of power to send to the heating element or burner to reach the desired temperature.

Heat Exchanger

Tankless water heaters work by warming up your water with a heat exchanger, which is a powerful device that transfers heat from warmed coils to incoming cold water.

Hot Water Outlet

The hot water outlet valve is the pipe the heated water flows from. It leaves the water heater and is pumped through the home to wherever water is needed.

Components Specific to Gas-Powered Tankless Hot Water Heaters


In a gas-powered tankless hot water heater, there is an ignitor that lights the gas burner whenever water starts to flow into the unit.

Gas Burner

When hot water is required for your shower, dishwasher, or faucets, the gas burner in a gas-powered tankless hot water heater is what ignites to heat up the heat exchanger. The water flowing through the unit is then heated to a preset temperature, which is determined by the temperature control knob (although sometimes the temperature control is digital).


Natural gas-powered tankless water heaters use a fan to vent combustion gases outside. They turn on when the unit is in use and turn off and on as needed.

Components Specific to Electric Tankless Hot Water Heaters


In electric-powered tankless water heaters, the triacs are what signal the heating elements to turn on.

Components of Boilers

Not all boilers are created alike. There are several different models that use various types of fuels and configurations depending on what they are used for. In this area, we outline the basic components of residential boilers to give you an understanding of how they work.


An aquastat is the boiler’s version of a thermostat. It’s the brains of the operation that tells the components when to turn on and off to keep the boiler’s output at the desired temperature.

Feed Pump

The feed pump is what pushes the water into the boiler for heating.

Gas Valve

Simply put, the gas valve is what supplies the burners with their fuel source (usually natural gas).


Like with gas-powered tanks and tankless hot water heaters, burners are where air and fuel combine to create heat. They heat the unit’s heat exchangers.

Heat Exchanger

A boiler’s heat exchanger consists of heated pipes in a chamber where water is forced through. As the water passes by these heated pipes, it absorbs the heat from the pipes and is then piped out through the building as needed.

Circulator Pumps

Circulator pumps are what keep the water flowing through the system. Water comes in, gets heated, and is forced out to where it is needed with the help of the circulator pump.

Supply Lines

After the water is heated, it goes out through the supply lines to where it is needed. These lines go all through the building through the walls to taps, faucets, radiators, and appliances.


Not all boilers have a condenser, but they are becoming more popular because are more energy efficient. They reuse some of the exhaust heat in the flue to heat water.

Pressure Relief Valve

With a device that creates steam, it’s absolutely critical to have safety in a place that will automatically open a vent to release pressure when it is too great. That’s exactly what the pressure relief valve does.

Vents and Flue

Boilers typically have at least one vent where excess heat is. They will also have a flue where exhaust from natural gas combustion is vented through ducts to the outside.


In the event that the boiler needs to have all the water inside it drained, it will exit through a drain that is located at the lowest point of the water tank in the boiler.

How Do I Choose the Right Hot Water Heater for My Home or Business?

Which Hot Water Tank Brands Can I Trust?

Many companies make hot water heaters, but there are some that we recommend over others. In this section, we’ll tell you about the brands we prefer.


Navien is a leader in innovation and design in tankless hot water heaters. They have the highest energy efficiency ratings in the industry and build their products using high-quality materials that will last a long time.

They offer 15-year warranties on their heat exchangers and 5-year warranties on their parts, so you won’t be stuck holding the bill if something goes wrong after a few years. Their sleek, compact design makes them ideal for residential settings because they are 80% smaller than traditional hot water heaters.

They boast an impressive 15 gallons of hot water per minute and since they heat water as it’s needed, you’ll never run out of hot water.

Check out the Navien website for more information.

Bradford White

Bradford White makes a hot water heater suited for every situation. They have an impressive catalogue filled with high-quality, high-efficiency industrial, commercial, and residential hot water heaters that are made using leading-edge technology.

To ensure that their products last as long as possible, they can only be installed by trained professionals like us at Kingstree Plumbing. They offer great warranties, a huge selection, and great resources on their website for troubleshooting and other information.

One model that we’re particularly impressed with is the Extra Recovery Atmospheric Vent Water Heater for residential applications.

AO Smith

AO Smith is another great company that specializes in top-of-the-line hot water heaters. They pride themselves on being technology innovators and were the first to introduce glass-lined tanks that stand up better to corrosion than traditional steel tanks.

To this day, they strive to create products that deliver maximum hot water output at the lowest possible cost.

They offer an incredible selection of hot water heaters. Everything from commercial to residential, with all kinds of fuel types and models to choose from. To see their selection of one of our favourite products of theirs: high-demand hot water heaters.

How to Choose a Hot Water Heater

If you want to have hot water in your home or business, you need to have a hot water heater. That part is easy enough to figure out. The part that’s not so easy to figure out is which one to get.

It’s important to get the correct size of hot water tank for your needs because if you buy one that’s too small, you’ll constantly be running out of hot water and if you buy one that’s too big, you’ll end up with higher purchase prices, higher utility bills, and wasted space.

Keep reading to find out how to choose the right-sized hot water heater.

Step 1: Determine Your Power Source

In Alberta, there are two main power sources for hot water heaters, electricity and natural gas. Depending on the cost, you may decide to go with one fuel type over the other.

In general, gas-powered hot water heaters cost less to operate but will cost more to purchase. For a more detailed comparison of gas and electric hot water heaters, read Gas vs. Electric by Winnipeg’s City Wide Water Heater Service.

Another thing to consider is that gas-powered hot water heaters need to vent their exhaust, so they may not be an option if there is nowhere for fumes to go.

Step 2: Determine the Amount of Hot Water You Will Need

Here are the factors to consider when figuring out how much water you use:

  • How many people are present? On average, peak use for one person is 10 gallons per hour in a house. In an office, the average peak hour use is only 2 gallons.
  • How many appliances are present
  • The age of your appliances

You’re probably thinking, How do I figure out how much hot water my home or business is going to use? The answer is, you don’t really need to! You can get daily or weekly estimates and just divide them by the number of hours in a day or week.

Hot Water Calculator from Rock Paper Sun Ltd

Hot Water Calculator from Ausgrid

Once you have an estimate of how many gallons of hot water you use, you should buy a hot water heater with a First Hour Rating (FHR) that is within a few gallons of your estimated use. The FHR is the amount of hot water a unit can deliver during peak time use. That makes sense, right?

Tankless hot water heaters use a different rating, which is gallons per minute, or GPM. To get this number, divide your gallons per hour rating by 60.

Step 3: Consider the Efficiency Factor

The Efficiency Factor (EF) takes into account the following things:

  • The Recovery Efficiency is how efficiently the heat from the fuel is transferred to the water.
  • Standby Losses, which is how much heat is lost from the stored water.
  • Cycling Losses, which is how much heat is lost as the water cycles through the unit.

The higher the EF number is, the more efficient the hot water heater is.

[Tweet “On hot water tanks, the higher the EF # is, the more efficient it is #plumbingtip #yeg”]

It’s a good idea to give some thought to your hot water tank selection so that you end up with the best one for your individual needs. That said, most brands have tools on their websites that will help you choose a hot water heater.

Here’s the Selection Assistant from Navien

Product selector from AO Smith

Water Heating Selection Guide from HTP

Hot Water Heater Safety

Not to be a Derek Downer, but just about anything can be dangerous, even innocent-seeming things like spoons or dust. Dropping a spoon on your foot can be painful, and dust in your eyes can cause you to crash your car! Your hot water heater is no exception. You might be surprised to hear this, but every year, a few hot water heaters explode! So read this next section carefully so your innocent hot water heater doesn’t become a danger to your home or business.

1. Setting the Right Temperature

Some like it hot, some like it cold. The temperature you set your hot water heater to is a matter of preference… to a degree. If your hot water tank is set too low, you risk breathing in harmful bacteria that could be killed by higher temperatures, but you’ll use less energy and have lukewarm showers, which can be nice in the summer.

On the other hand, if your hot water tank is set too high, you could end up with burns from putting your hands in super-hot dishwater or scalding showers.

The factory setting on your hot water heater is usually set to 125 degrees, but that can be too hot or inefficient, energy-wise. Changing the setting of the temperature on some hot water heaters is very easy. They will have settings like A, B, C, or vacation, lukewarm, warm, hot, and very hot, and you start with one and see if it’s hot enough for you.

[Tweet “Factory setting on your #hotwater tank is 125 degrees, but is that too hot? #plumber #yeg”]

You might see a temperature gauge with a range between 60 and 160 degrees, which can be a little trickier to figure out. It’s recommended that you set the temperature at least 120 degrees to kill the bacteria that cause Legionnaires’ Disease.

If that’s not hot enough for you, you can always turn the temperature up, just be aware of the risk of burning your skin. Below is a chart that tells you how long it takes skin to burn in water at varying temperatures.

To check to see if your water is reaching the desired temperature, turn on the hot water for a few minutes, then run a thermometer under it for a few seconds. If you make adjustments to the temperature, wait a few hours before testing it again.

2. Hot Water Heater Tank Explosions Can Happen!

Hot water heater tanks are pressurized cylinders with hot liquid inside of them. Sounds a little bit like a bomb, doesn’t it?

Usually, the water is set to the correct temperature, but if something goes wrong, like the heating element or burner won’t shut off, the temperature mechanism fails, or the temperature/pressure valve fails, you could end up with steam instead of hot water. Since steam takes up more room than water and can be trapped in the pressurized hot water tank, it has the potential to cause an explosion.

If you suspect that your hot water heater is producing steam instead of water there are a couple of ways to tell:

  • Steam is coming out of your hot water faucets.
  • Your temperature/pressure valve is leaking hot water or steam.

Don’t panic and run if you have the symptoms above. First, shut off the fuel source. For electric hot water heaters, turn off the power at the breaker. For gas-powered hot water heaters, shut off the gas valve.

Next call a plumber for emergency hot water heater service.

This actually happens! See for yourself in this funny retro video on the subject of exploding hot water heaters:

3. General Safety Tips for your Hot Water Heater

If your hot water heater uses a pilot light, make sure that you don’t have flammable liquids around it, including bug bombs. If it’s located in a garage, make sure that the pilot light is at least a foot and a half (18 inches) above the floor.

Keep the area around your hot water tank clear of dust and debris.

Proper ventilation is key with water heaters that use natural gas as fuel. Make sure that the vents are clear of dust and debris and that everything is connected. The vents should go straight up and outside without sections that go down.

Insulation is great for a hot water heater. It keeps the water warmer longer so that you don’t burn as much fuel to keep water at its desired temperature. Just make sure that the insulation is at least 6 inches from the flue exhaust and draft hood.

Another insulation-related thing to watch out for is that it doesn’t cover air intake vents or burner control.

Avoid storing anything on top of your hot water tank.

[Tweet “Don’t store things on your hot water heater! #safety #yeg #plumber”]

Hot Water Tank Maintenance

Whether you’ve inherited a hot water tank in the house you just bought or you’ve been living in a home for a while and haven’t checked on your hot water tank … ever… it’s a good idea to read over your water heater manual and give the unit an inspection (we’ll tell you what to look for).

If nothing seems amiss and you are satisfied with how it’s functioning, it should be good to go a couple of months before another check-up. Here is a schedule to follow for hot water heater maintenance.

Every Two Months

Check for water leaks

Check the plumbing joints and the water heater in general for any water leaks. You may see little pools of water. If you do, try to locate the source of the leak and then troubleshoot from there to see what could be causing the leak. It could just be a loose joint or a small crack in the pipes. A small pool could also mean that your pressure relief valve has recently opened, in which case you should check the water pressure in your house.

Check to see if the water tank or the surrounding pipes make any odd noises when a nearby faucet is turned on

Turn on a nearby faucet or have a helper turn on a faucet somewhere in the house and then listen for odd noises coming from the water heater, the pipes around it, the vents, and the gas line if your water heater is gas-powered.

Check for corrosion

Since minerals in the water can cause corrosion, you may see some signs of it around the plumbing joints. It looks like cream-coloured powder or crusty stuff around the water pipe joints or on the top of the unit.

Check the gas line for cracks, breaks, or the smell of gas

Gas leaks are nothing to mess with, and if you smell gas, you should call a plumber to inspect your hot water heater by using a bubble leak locator to identify the source of the leak. You can check the gas line for breaks or cracks, but they can be notoriously hard to find with the naked eye. Your best bet is to shut off the gas line and wait to see what the plumber finds.

Make sure the area around the water heater is clean and clear of debris

If you have kids or pets, you may find that things have found themselves shoved under your hot water heater. Check your vents, air intake areas, and around the pilot light (if your unit is gas-powered).

Check that the pressure relief valve opens and closes freely

First, you need to make sure that your hot water heater HAS a relief valve, then check to see that it is working properly. Missing or malfunctioning relief valves are the main cause of hot water heater explosions. See for yourself in this list of 101 Bad (or interesting) Water Heater pictures.

Here’s a video that shows you how to test your temperature and pressure relief valve.

Check the temperature of the hot water coming out of your faucets

You can make sure that your water heater is doing its job by checking the temperature of the hot water coming out of your faucets. Turn the water on and let it run for a few minutes. Then check the temperature with a thermometer. If there is a major discrepancy between the temperature the unit is set to and the temperature of the water coming out of your faucets, you may have a problem.

Every Six Months

Flush your system

Edmonton has hard water, meaning it has a high amount of dissolved solids like calcium, magnesium, aluminum, and iron in it that come out of the water and attach themselves to the inside of your hot water heater. These solids cause corrosion, meaning the metal insides of your unit can start to deteriorate.

Deterioration can cause all kinds of problems, so to avoid that, you should flush your hot water heater every six months to expel the solids and corrosive buildup.

Here’s a link to the Alberta Health Services’ guide to flushing your hot water heater that outlines all the steps you take to fully flush your system:

How Do I Flush My Water Heater

After Two or Three Years

Check the anode rod

In hot water heaters that have tanks, there will be an anode rod (also called a sacrificial rod) inside the tank. Its only purpose is to attract the solids in your water. Basically, the rod will corrode instead of the metal insides of your hot water tank.

They last up to six years, but it’s a good idea to check on it every year to see what kind of condition it’s in.

[Tweet “#HotWaterTanks have anode rods that wear out every 3-6 yrs. Check yours! #protip #yeg”]

For step-by-step instructions on changing out the anode rod check out this WikiHow article: How to Replace an Anode Rod in a Hot Water Heater. In order to check it you will have to take it out, so you can follow the same steps that are in the article. The only difference is you won’t be puttin