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What is a tankless water heater and how does it work

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When it comes to instant water heaters we have the best tankless water heater reviews so, if you’re looking to buy or get more information you are in the right place.

Tankless water heaters are just what their name implies: they heat the water you need to use on demand, rather than heating water stored in a tank and letting it wait to be used. They basically use high-powered burners or electricity to quickly heat water as it runs through a heat exchanger.

To understand how they really work, you would first need to understand how a standard tank water heater works. In a traditional heater system, you basically have a large tank that holds and heats water. To get the hot water when you need it, the standard tank continually heats the water and keeps it at the desired temperature. This means that there is energy being consumed to keep the water hot even when it is not being used. This is known as standby heat loss.

On the other hand, a tankless water heater is not subject to standby heat loss because it heats the incoming water only when you need it, hence the term “on demand water heaters”. This is the main feature that makes them so energy efficient.

There are mainly two types of tankless water heaters: point of use and whole house heaters.

Point-of-use systems are compact in size and can fit in a closet or under your kitchen sink and they can heat enough water for one or two outlets. They are usually installed close to the outlet whether it is a shower or a kitchen sink. Installing them next to the outlet means there is no lag time for the hot water to reach your outlet. Lag time is the length of time it takes for the hot water to reach your outlet and this can sometimes be as long as several minutes. While this may not seem like an important issue, you need to bear in mind that you may be saving on your heating bill, but you may also be running up you water consumption.

The second type is the whole-house system. These are larger, more expensive to buy and can operate more than one outlet at a time without lag time. They are powerful enough to supply hot water to more than two outlets at a time without having the water temperature suffer as a result. They will provide you with a constant flow of hot water even if several outlets are being used simultaneously.

Finally, you also have the choice between electric, propane or natural gas models. The small point-of-use models are usually electric while the whole-house ones are powered by either propane or natural gas.


Once you’ve figured out your flow rate and needed temperature rise, you will be able to make the correct choice. Gas and propane powered instant water heaters provide a lot more power and are mainly used for whole-house systems. If you have a family and need to run several water outlets at the same time then this is the choice for you.

If you are single or living in a household of two people, the electric model should suit you just fine. If you still want to ensure a hot water supply for several outlets in your home, you can install more than one electric tankless water heater at several outlets and you will have a more constant supply of hot water on demand.


Whether your old tank heater has broken down or you’re just thinking of switching to tankless, your main concern should be how much money will I be saving. A small comparison will show you that on demand water heaters cost more to buy and install but your return on investment is usually around 18 months.

However, you won’t be constantly heating up water in a tank since instant water heaters will give you the hot water you need instantaneously and only when you need it. This, in the long run, is where you will be saving a lot of money on your energy bills.

Another point to consider is the lifespan of a tankless water heater in comparison to a traditional one. While the traditional water heaters last up to 10 years, a tankless water heater can serve you for 20.

The advantages of a tankless water heater
Electric vs Gas – Tankless water heater

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