How Does a Tankless Water Heater Work

How Does a Tankless Water Heater Work

For some years now, people have been starting to use tankless water heaters. Besides the fact they don’t have a tank and don’t need electricity for keeping the water hot in a tank-like traditional water heating systems, tankless water heaters bring plenty of benefits to the table.

What’s the main principle behind tankless water heaters?

Tankless water heater heat water directly, without collecting the water in a tank. When you’re turning the tap on, cold water goes through the pipe into the unit. An electric element or a gas burner (details down below) will heat the water. Therefore, the tankless water heater will give hot water almost instantly. There’s no need to wait for the storage tank to fill with water.

Some may argue that tankless water heater’s main downside is the limits of flow rate, but there are far more benefits than shortcomings to consider.

How to explain the working mechanism of tankless water heaters?

A tankless water heater will simply heat water (using electricity or gas), before giving it back to your home’s fixtures. The tankless water heaters heat water without storing it in the tank, but drawing and heating water on demand only when you need it.

Several aspects give different categories of the tankless water heater. The shape, the specifications, type of application, and flow rate are some of the criteria making the differences between the tankless water heaters. However, the most significant factor is the fuel type firing the units.

What type of fuel do you want to go with?

The fuel type is the most significant aspect of the tankless water heaters world. Nine times out of ten, it’s the first thing to consider when selecting your unit. Most tankless water heaters are fired by gas or electricity, but there are units fired by propane, solar power, fuel oil, and even geothermal energy.

The price and the availability of the power source in your area are also aspects that count when selecting your water heater.

For instance, gas tankless water heaters are the most popular option in high-demand applications. It’s because they can produce more hot water at a faster speed than other kinds of tankless water heater. There are numerous areas where gas is more available and more affordable. It does need venting, though, and installation isn’t a breeze. You need to be mentally prepared for the costs and efforts when installing a gas-fired tankless water heater.

Electric tankless water heaters prove to be reliable in applications with low and medium hot water demand. The maximum output would be 8GPM, which is enough for a small household. Keep in mind that electric units are less powerful than the gas opponents.

Should you try to save some money, the electric tankless water heaters are a better option as they’re cheaper than the gas units. They’re also easier to install and don’t require venting, so the initial investment is lower than with a gas unit. Electric models don’t need much maintenance, becoming a reliable option in a secondary residence. People with limited mobility or skills to take care of the tankless water heaters should also go with electric units.

What’s the working mechanism for gas tankless water heaters?

Most of the time, tankless water heaters may produce hot water with a 2-5GPM rate, with gas models being able to perform a higher flow rate than the electric units.

However, even the largest gas-fired unit cannot give hot water for several fixtures at the same time. For example, it may be difficult for a gas model to support a shower and a dishwasher at the same time. In order to surpass the limitation, you may have to install two and even more tankless units. You have to connect the water heaters parallel so that you can use several fixtures at the same time.

Another solution would be to install different units for specific appliances, with dishwasher and washing machine requiring separate water heaters most of the time.

Here’s how a gas-fired unit works:

  • When you need hot water for a washing machine/dishwasher, faucet, or shower, cold water will flow into the unit from the inlet pipe. Typically, the tube is at the bottom of your heater
  • The water heater ignites the flame, heating the heat exchangers
  • Water will be preheated as it runs through the heat exchanger (stainless steel is an excellent material for the heat exchange), gathering any extra heat before escaping into the venting

The heat exchanger includes several tubes that pass by gas burners for heating the water. It’s a fundamental piece of the tankless water heater.

  • As the water goes through the heat exchanger, it’s going to be heated some more. It gets outside through the hot water outlet pipe, traveling through the pipes to the water fixture where you need the hot water
  • The unit adjusts the flame output so that the temperature setting is maintained
  • When you shut off the hot water fixture, the cold water will stop flowing into the heater, whereas the flame will extinguish. Until you use the hot water once again, the unit will remain off.

Recirculation Technology

Some manufacturers developed recirculation technology. It lets you establish recirculation patterns that match the hot water usage patterns. You will have hot water as often as you need, but there will be no circulating when you’re not using the hot water.

Is the working mechanism of electric tankless water heaters complicated?

Some people refer to electric tankless water heaters as on-demand, since they only run when you’re tapping the hot water.

Here’s the brief description of the heating process:

  • You turn on the faucet/appliance where you need hot water
  • The flow sensor in the unit identifies the water flow
  • The water will start flowing over the electric elements that heat it as it goes over
  • Hot water comes out of the fixture

The conclusion

Both gas and electric tankless water heaters have their ups and downs, and you should give it a good thought before selecting one of the two. At the end of the day, it’s all about cutting down your utility bill and using less energy and space for your water heater.

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