For an average person, the words ‘water heater’ would generally create an image of a big metal tank that you put up in large spaces. One might wonder how these machines work.
The water heaters work by repeatedly storing and reheating water whilst waiting for the water to be used by you. It might be obvious now that it is not a very efficient system as it keeps using energy during the reheating phase. Most people might not even know that an entire category of water heaters that have no tank at all does exist!
Now, the question arises, “How does a hot water heater without a tank work to heat and store the water?”
In this article of ours, we will discuss how different tankless water heaters work, including the electric tankless water heaters, gas tankless water heaters, whole house and point of use tankless water heaters and their benefits.
First off, what exactly would you benefit from installing a tankless water heater? What features does a tankless water heater offer?
Takes up less space
These water heaters do not require storage tanks. Therefore, they consume less space as compared to a tank-type water heater. This is one of the main points of differentiation between them and the tank-type heater.
They are more efficient
Tankless water heaters are more efficient than their counterparts. Usually, tankless water heaters are about 30 to 35 percent more efficient. If you don’t consider the initial set up cost, tankless water heaters save a lot of energy and reduce your expenses.
More durable and longer lasting
Compared to the traditional water heaters, tankless water heaters tend to last for a longer time. On average, tank-type water heaters last for around 10 years while the tankless models last about 20 to 25 years.
Low maintenance cost
Tankless water heaters rarely face problems compared to their tank type competitors. Any problems that they do face, can be resolved pretty easily. So, you normally wouldn’t require a plumber or electrician and can easily deal with it yourself.
What Is A Tankless Water Heater?
Before choosing any appliance for your home, it is in your best interest for you to know its functioning and the pros and cons.
Tankless water heaters heat water by using gas or electricity and then provide you with hot water. This delivers a nearly endless supply of hot water and provides instantaneous comfort and convenience.
Unlike traditional water heaters, the hot water supply is not stored in the tank. This makes a tankless water heater a cost-effective conservation option because rather than storing the hot water in a bulky tank, these systems draw, heat water and provide it to the fixtures on demand right when it is needed.
They can also be differentiated by fuel type, flow rate and type of application.
Types Of Tankless Water Heaters
There are two main types of water heaters, one is a gas tankless water heaters and the other is an electric tankless water heater. There are also sub-categories as to whether they would be whole house or point of use.
First, we need to explain about the different types of fuel.
Types Of Different Tankless Heater Fuel Sources
Fuel types are the main difference between the working of all the tankless water heaters work. As a result, it is often the first decision a buyer needs to make when scouting the market for hot water heaters.
Most tankless water heaters are powered by electricity or natural gas, but they can also use propane, solar energy, geothermal energy and fuel oil. Customers are advised to select the water heater’s fuel type by the price and availability of the different power sources in their locale.
Gas tankless water heaters are generally preferred for the more high demand situations, this is because of their ability to provide more amount of hot water at a faster rate than the other types.
Gas is favoured more since it is generally more widely available and more affordable compared to the others. Installation of a gas tankless water heater could be difficult because its venting requirements can turn out to be pretty expensive.
Electric tankless water heaters are also very effective, especially where water demand is average or lower. They normally provide a maximum flow rate of 8 GPM, which is enough for a smaller family but is still much lower than what a gas tankless water heater can offer.
For those who are looking to save money, an electric tankless water heater is a better option because they are much less expensive and easier to install. Electric tankless water heaters require low maintenance, which makes them an ideal option for those looking for a hassle-free and inexpensive experience.
Gas Tankless Water Heaters
Gas tankless water heaters run on either kerosene or propane. Some models run on both. Before installing one of these heaters, you would need to assess different things. Firstly, it is important that you make sure that your house has adequate ventilation.
Read More: Best Propane Tankless Water Heaters
Some units come along with vents that allow the gases to escape either through the walls or the roof. These models are best for places that lack venting systems.
If your hot water demand is high, the gas-type tankless water heater is a great option.
Gas tankless water heaters and the traditional water heaters are almost similar. The two types use the same principle only that one lacks a storage tank. Gas-types work when the faucet is on. Cold water flows into the heater, a sensor detects the flow and immediately activates the burner.
The gas burner heats the heat exchanger which the water encircles. They pass through the heat exchanger. A heat exchanger is just a series of tubes which pass by gas burners to heat up the water.
The heat exchanger is a critical piece of the puzzle in tankless gas engineering. Once the water gets to the right temperature, it leaves the heater and then through the fixtures. An adequate ventilation system will ensure a safe passage of all harmful gases.
Gas tankless water heaters are mostly energy star-rated too. They use secondary heat exchangers that make them more energy efficient. This is only when they are compared to other water heaters which don’t have an energy star certification. Secondary heat exchangers get heat from the combustible gases, this helps condense the gases.
Regardless of how a hot water heater works in terms of fuel type, the GPM capacity requirement will depend on the daily water demand of the household. People who question the effectiveness of tankless heaters might have had an incorrectly sized unit installed.
For example, a person who only has one bathroom and no on-site laundry or dishwasher will only need a 5 GPM water heater at the most.
Read More: Best Rheem Tankless Water Heaters
Electric Tankless Water Heaters
Now that you know how a gas tankless water heater works, we will look at how specifically an electric water heater works. So, how does an electric tankless water heater work, after all?
Tankless water heaters are sometimes also called “on demand”, because they only begin working once there is a demand for hot water, as opposed to tank heaters that store warm water.
Electric water heaters use electricity-powered heating elements to heat water. They work on the principle of converting electric energy into heat energy.
The heating elements are in contact with water, reducing heat loss during the process. Similar to the gas-type water heaters, the heating process begins when a faucet or appliance is turned on and a flow sensor detects water flow.
At this time, the water flows over electric elements that heat it as it passes by. From here, the warm water is fed to the fixture requiring hot water.
This working mechanism has gained it the name “instantaneous heater.” Immediately the flow of water stops, the heater cuts the supply of power to the heating element. This leads to minimal wastage of water and power.
Electric tankless water heaters are compact, easy to install and do not consume a lot of space. They use electricity as the sole heating element. Unlike their gas-type counterpart, an electric type does not need venting since it doesn’t emit any harmful gases.
They are more suited for places that are costly or places where it is impractical to add venting. The best selling point of an electric water heater is their size. They are small enough to be installed in almost any place the buyer finds fit.
For example, the consumer can fit it in the bathroom, under the sink or virtually any other compact space. So, it can stay out of sight too. The closer it is to the fixture, the lesser time it will take for the hot water to reach the intended point of use.
Its working mechanism is pretty much the same as that of a gas tankless water heater. One of the noticeable differences is that they use a heating element. This is as opposed to the heat exchanger present in a gas heater.
The electric heater is set to work with a certain rate of water flow. If exceeded, it may not function at the same efficiency as before. You can customize the settings to maintain a constant temperature. This is even if the rate of water flow changes.
Read More: Best Rinnai Tankless Water Heater
Types Of Application For Tankless Water Heaters
When buying a tankless water heater, another decision is whether to use whole house or point of use water heaters. Once again, the industry has given us some self-explanatory terms to use – these are exactly what they sound like.
The application doesn’t really affect how the tankless water heater works but can require specialized features which can be helpful for people in certain situations.
Whole house tankless water heaters mean that there would be one primary water heater that supplies hot water to the entire residence. If the demand is too high for one heater to handle, they can be “combined” or connected with other units which are compatible with them to increase their output capacity.
Heat loss can occur as water travels through the pipes, so the farther away the fixtures are the more of an issue this could be. Therefore, if you require instant hot water, it is best to have it installed in close proximity to the fixtures. If you think about how hot water heaters work, this is true for a traditional tank heater.
After this, we will answer the question “What exactly is a point of use water heater?”.
Point of use water heaters, unlike the typical whole house use water heaters, are installed in close proximity to the fixture that will require hot water. They are intended to be installed within two feet or less of the fixture, kept out of sight under a sink or in a small utility closet.
Point of use systems are generally installed when the fixture is too far from the primary heater or is otherwise difficult to include in the main water heating system.
In a matter of thinking, point of use tankless water heaters are basically the same as whole house water heaters. The only difference is that these heaters are typically installed within two feet of the fixture requiring heat, like under a sink. When water flow is detected by the sensor, water is heated, then fed to the faucet or appliance.
Since point-of-use water heaters are installed in a living space rather than a mechanical room or basement, they are much more compact. The small stature of the equipment also results in lower power, so the point of use heaters can only be used for such low use fixtures.
With all that being said, these water heaters have the same purpose as the conventional ones but are different in the method of functioning. Unlike conventional heaters, they provide hot water only when needed which completely guarantees your convenience.
To summarise, the electric-type tankless water heaters are cheaper but more efficient. Their energy consumption is also higher than the gas powered ones. For gas-type tankless water, they are pricier but more energy efficient.