One can hardly imagine living without hot water today and we will definitely feel uncomfortable without it. That’s why there must be a water heater installed in every home.
There is a huge variety of water heaters of different types and brands presented on the market. In this review, we will cover the purpose, advantages, and disadvantages of the main types of water heaters.
Types of water heaters
Electric water heaters
The simplest and most affordable water heaters are electrical ones. We shall describe them in more detail.
The most popular type is a storage electric water heater. It is a cylindrical tank or a tank of a rectangular parallelepiped shape with a volume from 5 liters and more. The water is heated by a tubular heating element located inside a tank. The power consumption depends directly on the tank volume and usually less than 2-2.5 kW (for a 100-liter tank). Most models have a power control, heaters with electronic control also allow adjusting the heating temperature.
The current problem of energy saving can be solved with modern “smart” water heaters, which remember their users’ habits throughout the week and heat up only the required volume of water to their arrival. As such water heaters do not work when the hot water is not used, the energy saving is 25%.
The volume of the electric water heater is calculated according to the number of water supply points or the approximate flow rate. It is considered that taking a shower for one person needs about 30 liters of water, two people – 50-80, three 80-100 liters.
The inner surface of a water heater tank is made of stainless steel or covered with a special enamel to prevent corrosion. Tubular heating elements can contact with water (so-called “wet” tanks) or be located in a special protective flask (“dry” tanks).
The lack of direct contact with water significantly extends the heating element’s service life and makes it easier to replace. The advantages of storage water heaters include their simplicity, low-cost installation, and economy. The main disadvantages are their size and the limited volume of the heated water.
Tankless water heaters
This type of water heaters is less common, mainly because of its more complex installation. A tankless water heater heats water only when it is turned on – a heating element instantly heats up the water coming through a heater. Tankless water heaters are more compact, not limited in the volume of heated water, but consume more electricity – for example, to take a shower, the tankless water heater capacity must be 12-16 kW. At that, the heating temperature depends on the temperature of water at the inlet. Tankless water heaters usually heat up water by 20-30 degrees. They can not be used in apartments without a separate electricity line for connecting appliances with a capacity higher than 5 kW, so their owners must choose a more economical storage water heater instead.
Gas water heaters
In houses connected to the gas pipeline, a tankless gas water heater can be installed. It is more compact than the storage electric water heaters and more cost-efficient. But its installation is more complicated compared to electric water heaters. One of the requirements for its installation is free airflow and the gas exhaust system (to the ventilation or outside).
The operation mechanism of a tankless gas water heater is very similar to an electric one. Water passes through a heat exchanger, where it is heated. A heat exchanger, in its turn, gets heat from natural gas combustion. Combustion products are exhausted by force or natural draft to the ventilation shaft (in “chimney” or “atmospheric” models, with an open combustion chamber), or through a special pipe outside (in “turbocharged” models or models with closed chamber combustion).
Turbaned models intake air from the outside and the combustion products are exhausted outside as well. Such water heaters can be installed in the high-rise buildings. Heaters with an open combustion chamber require a constant inflow of air into the room, the combustion products are exhausted into the ventilation shaft or chimney.
Gas water heaters can be of 4 types according to their ignition method. Manual ignition is almost never used today. Piezo ignition is used in inexpensive models, the flame in the burner is ignited by pressing a button.
Electronic ignition or ignition from the battery is more convenient – the flame lights up when the water is turned on and the spark is generated by the battery.
Heaters ignited from a generator or turbine do not require the installation of batteries, as the spark comes from a generator that drives the flow of water. Heaters with electronic ignition and ignition from the turbine are most convenient, as a water heater is switched on when the tap is opened and switched off automatically when the tap is closed. This allows reducing gas consumption and increases device safety.
The type of burner is also important. It can be with a constant (stepwise) power or variable (automatic adjustment) power. Burners with constant power, installed manually, are less convenient – the temperature of hot water at their output depends on the flow rate and can be different. Heaters with automatic adjustments do not have such a drawback – the selected temperature will be kept up automatically, regardless of external factors. The power of the inline gas water heater is also very important. The higher the power, the more water points can be connected to a heater.
Modern gas water heaters are high-tech devices, subject to high safety requirements. Most of them have a sensor system that automatically stops the gas supply when the flame fades out, there is no water flow, as well as temperatu