How Does a Tankless Water Heater Work?

If you are thinking of replacing your old water heating unit nothing can be better than a tankless water heater. This water heating unit is the most energy-efficient one and needs minimal maintenance. But before getting a tankless water heater installed, many people often wonder how does a tankless water heater work?

As the unit’s name implies they have no hot water storage tank so water is heated on demand. This helps prevent heat energy loss. When the faucet is turned on the cold water in the pipes passes through the heating elements and is thus heated. The thermostat temperature is set to heat water according to the needed temperature.

In this article, we will talk about the working of a tankless water heater to know how a tankless water heater works to provide an endless supply of hot water. if you need one or not. It is an established fact that tank-less water heaters are more energy-efficient than the traditional ones. But how does it happen so? We will know the answer to this question by understanding the way they function.

Working of a Tankless Water Heater

Tankless water heating units heat water only when the faucet is turned on. Water is not stored prior to use. When you turn on the tankless water heater and the faucet is also turned on water starts running through the pipes. This water in pipes is heated by a gas burner or an electric element. Thus one gets heated water supply on demand. The only drawback of such a unit is that it limits the water flow rate. It happens to cause the water heating to start on opening the tap so you’ll have to wait for some time.

A tankless water heater can provide about 2 to 4 gallons of hot water in a minute. Gas tankless water heaters are better when it comes to the amount of water supply. Some buyers complain of a shortage of hot water supply and this can happen if many faucets are turned on simultaneously.

For optimal functioning of a tank-less water heater only use one faucet at a time. If your demands can be met with a single faucet then install a separate water heater for all appliances. Overloading one water heating unit can result in damage so increasing their number is a good option. Multiple tankless water heaters can be connected in a row so water is heated more quickly.

Tankless water heaters can be used with any appliance that needs water for functioning. Dishwashers, washing machines, and bathroom tubs all can be connected to a tankless water heater.

How does a Gas Tankless Water Heater Work?

A gas tankless water heater works on the same principle as the standard gas water heater. As ones with bigger families choose to own a gas tankless water so it’s important to know the way how such a unit works. The only difference is in the storage tank.

They are more energy-efficient cause they heat water only on demand and thus prevent standby energy loss. When the water faucet is turned on cold water runs to the water heater. The flow sensor then starts working by lightning on the gas burner. The gas burner heats up the heat exchanger.

Incoming water is heated by the heat exchanger and then leaves the heater at a set point temperature. Combustion gases safely exit through a safe vent system. By only heating water on-demand, a tankless water heater offers great energy efficiency. The steps of a gas tankless water heating working are as follows

  • The water faucet is turned on by the user.
  • A flow sensor detects water flow to the heat exchanger and directs the control panel to start heating this water.
  • A gas tankless water heater the control panel opens up the gas valve so gas can come to the heat exchanger. It also ignites the burner.
  • The heat exchanger then transfers the heat from the flame to the water flowing through the pipes.
  • Next, the mixing valve tempers the water.
  • The temperature sensor detects if the water temperature is as desired or not. If it falls short of that needed for functioning then the unit adjusts the gas, water, and mixing valve accordingly.
  • A vent carries away all the gases.

How does an Electric Tankless Water Heater Work?

Now that we have discussed how a gas tank-less water heater works we will try to know more about the electric ones too. These are the units that supply hot water super quickly. Tank-less water heaters are named on-demand water heaters too. And this is because they heat water when the faucet is turned on.

When the faucet is turned on a flow sensor in the unit detects the cold water flow. Now the water passes over an electric element that heats up the water. From here the hot water is then transmitted over to the water faucet. With electrically wired homes, it’s easy to install a new electric unit without much hustle.

Advantages of Tankless Water Heaters

The first point of advantage worth mentioning is their energy efficiency. For an average water demand, these units can be about 30 percent more energy efficient. For greater water demand and supply they can be about 15 percent more efficient than the traditional ones. By increasing the number of water heating units up to 50 percent energy efficiency can be achieved.

The installation cost of a tank-less water heater is higher but it’s not a major concern cause in the long run they have low running costs and waste less energy. Tank-less water heaters have a long functioning life lasting about 20 years. The parts of a water heater can be easily replaced. A traditional unit however will last only for about 15 years at most.

Energy loss can be an issue with tank-less gas-fired water heaters. As the pilot light is burning continuously so the energy gets wasted. In the case of tank water heaters, the energy is used to heat the stored water. Gas-fueled water heaters have a higher flow rate than electric ones.

The cost of gas usage by the water heater varies from unit to unit. Before purchasing a unit ask the owner for the estimated running cost. You can opt for an intermittent ignition device water heater because they don’t waste energy. The pilot burns only when needed and so is more economical.

Keep some key important factors like fuel type, cost of running, and energy efficiency of the unit in mind before making a purchase. We have listed the most important pros next so you can easily look for detail.

Compact size

Nowadays city homes have congested spaces in which big size units can’t fit. This is a con of tank water heaters that they have big size. Due to the need for thicker insulation to prevent standby heat loss, they occupy more room. This means newer tank water heaters need more space than the traditional ones. So if you live in a small apartment or you have a big family then you can’t afford such a huge empty space. Tank-less water heaters come in handy here. These sorts of water heaters have the size of a suitcase and can be even hung on a wall.

Enhanced safety

The major concern with water heating units is the safety of the building and the people around it. The heated water is not stored in a tankless water heater. If your tank water heater ever starts leaking then it can spill gallons of water. Moreover, bacteria can grow easily in such a storage tank. If a natural calamity such as an earthquake hits the storage tank can spill and cause havoc. The tankless water heater is safer cause the combustion gases like carbon monoxide can’t be released into your home through the unit cause its vent is sealed.

No tank emptying before winter

The owners of storage tank water heaters know well how much effort it takes to empty a tank before winter. That’s not the case with a Tankless water heater because they can be drained using a compressor in minutes. After you have drained the water heater just unplug it.

Sensitive to water flow rate

Do you clean your water heater every month? If not the chances are that the minerals can build up inside and damage the parts. Monthly maintenance helps prevent this from happening. If there is much mineral build-up inside the pipes or the faucet it will impact the water flow rate. When the water flow rate falls down to 0.3 gallons per minute the unit will shut down automatically. This is because these units need a minimum water flow rate to keep functioning. When the unit is not receiving the required amount of water it shuts down as a safety measure to prevent a hazard to essential parts.

Economical benefits take time to show

The cost of a tankless water heater is about double the cost of a storage-tank water heater but they are more energy-efficient so they save money. The amount of money saved each month is about 100 dollars. This might not feel much significant at the time but as years pass by the cost advantage starts showing. The tank-less water heaters last long than energy-efficient water heating systems while the traditional ones start showing signs of demise quite early.

Need for proper installation and maintenance

If properly installed and provided with regular maintenance the unit offers better energy efficiency. Right installation of the unit depends on many factors like the fuel type, size, climate, building safety issues, and code requirements. Considering so many factors ask a local plumber to help you with installation. Before making the contract make sure to ask for an estimated cost of installation. If you are eager to self-install the unit then take help from the manufacturer as they can provide you with an installation manual that guides you with steps that you need to follow. It also mentions some important points that you must keep in mind while installing the unit.

The units need periodic maintenance too. This helps in preventing the mineral build-up which will destroy the unit otherwise. This maintenance can be done easily at home.

Differences Between an Electric and a Gas Tankless Water Heater

If you have decided to buy a tankless water heater then now you need to decide whether you want an electric one or a gas one. The difference in the operation of these two is that in an electric one the water is heated by an electric element and in the gas one a gas burner is used for heating. Another important advantages of electric heaters are that they take up very little space. They are highly energy-efficient up to 99 percent. As the homes are already electric wired so it becomes very easy to install the unit. The process is seamless. Installing an electric water heater has a much lower cost than the gas one.

The gas heaters are not as energy-efficient as the electric ones but these units have better heating power. If you have a big family with enormous energy demand then it’s better to get a gas-operated water heater. The installation cost for a gas-fueled heater would be higher than an electric one but if your home is not already wired for the electric one then getting a gas water heater is apt for you.

Water Heater Repair

Water is important for cooking, cleaning, washing, and bathing. If the water supply is disturbed it can create many issues. To avoid all these make sure you give the water unit proper maintenance. Even if any issue occurs call an expert technician to help you solve the issue.

New Tankless Water Heater Modifications

New advancements are being made in every field. Similarly, the tank-less water heater is being improved to become more useful for the owner. These latest modifications in the tankless water heating units are

Enhanced Efficiency

New gas heaters have a Condensing technology that uses about 96 percent of the heat of the fuel. This is due to a second heat exchanger system that redirects the exhaust heat for reuse before it leaves the unit through the vent. They have a high purchasing cost as they are 25 percent more expensive than the non Condensing ones. The condensing gas water heater forms an acidic condensate that needs to be neutralized. Some heaters have a built-in neutralizing cartridge, if your unit does not have one then you will have to add it yourself.

Quick Hot Water Supply

Water heating with a tank-less water heater might just take about 15 seconds but you still have to wait for that hot water to arrive at your faucet. If the distance between the heater and the fixture is long then look for a unit with a recirculation pump so it saves water and reduces waiting time. This pump can be pushed on by a button or a smartphone. It recirculates the cold water in pipes to the heat exchanger. Within a minute of doing so the pump shuts off and you get instant hot water as the tap is turned on. With the fast lifestyle of today, this feature is very helpful.

WiFi Connectivity

Now a tank-less water heater can be connected to your phone. Yes, you can adjust water temperature, hot water usage, and gas supply from your smartphone. Moreover, the smartphone can display an error code whenever there is a problem with the water heating unit.

This error code explains the cause and possible solution to the issue. The owner can even show the error code to the plumber and they will tell what to do. This feature also comes in handy in the sense that it tells about the time your unit needs descaling. Thus you can have proper unit maintenance on time.

The right size of the tankless water heater

The BTU output of a tankless water heater should be according to the demand so it will not supply lukewarm water instead. Three factors are important while determining which unit will match the water needs of your home.

  • Water temperature
  • Water demand in gallons per minute
  • The water heater energy efficiency

With years of experience under his belt, Adam decided to put his water heater knowledge to work. By providing high-quality content and expert guides, Adam hopes to help anyone looking for expert water heater advice.