The main parameter that they are guided by when choosing an instantaneous hot water heater is an indicator of the volume of water that it is able to heat.
In order to comfortably use this water heater in a private house, you should adhere to the following indicators at the points of the fence:
- from the sink tap – 4.2 liters per minute (0.07 liters / second);
- from a bath or shower tap – 9 liters per minute (0.15 l / sec).
For example, one instantaneous hot water heater is equipped with three parsing points, represented by a sink in the kitchen, a washbasin, and a bath (shower). If your goal is to find a heater for your bathtub, then you need a device capable of delivering at least 9 liters of water per minute at + 55 ° C. This hot water heater allows you to use hot water from two sources at once – a sink and a washbasin.
It will be possible to use hot water in parallel both in the shower and in the washbasin if the heater produces at least 9 l / min + 4.2 l / min = 13.2 l / min.
Manufacturers, as a rule, in the technical characteristics of the device indicate the maximum performance indicator, taking into account the heating of water for a certain temperature difference, dT, for example, +25 ° C, +35 ° C or +45 ° C. Thus, if the temperature of the water in the water supply system is +10 ° C, then the temperature of the tap water after heating will reach +35 ° C, +45 ° C or +55 ° C.
It should be noted that a number of sellers can indicate the level of the maximum performance of the device, but they do not write for what temperature difference it is intended. For example, you can purchase a gas water heater with a capacity of 10 liters per minute and it will heat up to a maximum of +35 ° C. Using hot water in a private house with such a device may not be so comfortable.
In this case, in a private house, it is better to use a gas water heater or a double-circuit boiler, the highest performance indicator of which will be at least 13.2 l / min at dT equal to +45 ° C. The power of the gas appliance will be approximately 32 kW.
When you choose a device for hot water supply in a private house, you should also pay attention to the minimum performance indicator at which heating is activated.
If the speed of water movement in the pipe does not reach this value, the water heater will not start working. Therefore, it is often necessary to consume much more water than necessary. It will be advisable to select a device with the lowest minimum performance, for example, no more than 1.1 liters per minute.
The maximum power of electric instantaneous water heaters, often used in a private house, ranges from 5.5 to 6.5 kW. Provided that the maximum productivity of the device is from 3.1 to 3.7 liters/minute, the water is heated by dT equal to +25 ° C. One device is designed to serve one point of water sampling in a private house, which can be a shower, washbasin, or sink.
Is it profitable to supply hot water to a private house with a storage heater (boiler) and water circulation
As a rule, the lower part of the tank of a water heater contains two heating elements – an electrical heat exchanger and a tubular heater powered by a heating boiler. A boiler is used to heat the water in the tank.
Such a heater is also called an indirect heating boiler.
Hot water in the indirect boiler is drawn from the top of the tank. In this case, the lower part is instantly filled with cold water from the water supply system, heated by means of a heat exchanger and goes up.
In other countries, all systems in modern private houses are necessarily equipped with an element such as a collector (solar heater). In order to connect the solar collector to the bottom of the indirect boiler, an additional heat exchanger must be installed.
The water in the boiler is heated by a solar collector. In the event that this is not enough, a boiler or electric heater should be connected.
How does the hot water supply of private housework with a layer-by-layer heating boiler
The heated water comes from the top of the tank. Instead, cold tap water immediately begins to flow into the lower part. With the help of a pump, water from the tank passes through the flow heater, then enters the top of the tank. Thanks to this, the consumer instantly receives hot water, and there is no need to wait until the entire volume of water is heated, as in the case if you use an indirect heating boiler.
Due to the fact that the upper layer of water heats up quickly enough, you can install a more compact boiler in a private house and reduce the power of the instantaneous water heater.
There are two-circuit boilers equipped with a built-in heater or remote layer-by-layer heating. Thus, this equipment of the domestic hot water supply system is distinguished by lower cost and compact dimensions, in contrast to indirect heating boilers.
The water in the device heats up in advance, even if you do not use it. The amount of heated water is enough for several hours of consumption.
Due to these properties, the water in the tank heats up for a long time, while the thermal energy in the hot water will constantly accumulate. Therefore, such a heater is also called a storage water heater.
Due to the long duration of water heating, you can give preference to a relatively low power heater.