Modern man can no longer imagine life without hot water. Moreover, not only at home, but even in the country. In the absence of a central supply, many decide to install a boiler to heat water. The indirect temperature increase model is considered to be the most popular recently. It is one of the most unpretentious and at the same time economical.

What’s this?

There are two types of similar tools that are similar to each other: a direct and indirect heating boiler. The second option is a liquid heater that uses the heat of the heating system.

The main difference from another type is that the unit raises the temperature of the water not through electricity, but through central heating or a boiler.

Most often, a barrel is used as an outer casing. At the same time, cubic installations have become more popular recently. They are made in the style of the main boiler and are often installed directly below it, thereby saving space in the room.

How does the system work?

Many have heard, but do not know how an indirect heating boiler works. The principle is simple. There is an inner tank which is made of stainless steel or even plastic. From above it is covered with a special heat-insulating material. Inside, a metal heat exchanger (usually made of brass) is most often installed. It is through it that the liquid from the boiler is launched. To ensure fast heating, it is made in the form of a spiral coil.
The case is created in the style of other models of the manufacturer.

A magnesium anode is built in to protect against corrosion. To protect the system from high pressure, a thermostat and a special valve are used.

There are also options on the market that have a different indirect heating boiler device. So, for example, it can be a “tank in a tank”, and the coolant is let in between the walls. In addition, several components are used at once for heat exchange. Similar designs are found on the market much less often than the main version.

To fill the tank, cold water is connected. Also in the tank there is an outlet for hot. Cold water enters the heater, and at the outlet the consumer receives already hot. Each such boiler is connected to a pipeline through which the coolant passes through the tank and the boiler. Such a system necessarily has a pump to create forced pressure in order to circulate the liquid.


This system has many advantages:

  1. The operation of the water heater cannot overload the electrical circuits in the room, as it is completely dependent on heating and does not consume energy.
  2. Successful models have a high efficiency and an optimal ratio of the consumables.
  3. The coolant does not interact directly with running water. This allows you to significantly increase the service life of the unit.
  4. The device of the boiler for heating water allows you to immediately supply hot water — there is no need to pre-drain.
  5. The unit can always be connected to an alternative heat source.
  6. It is possible to use several heating elements.


Despite all the advantages, this design also has a number of disadvantages:

  1. The initial cost of such a boiler is higher than electric or gas.
  2. The first heating of a tank of 100 liters is carried out in 1-2 hours, which immediately affects the heating.
  3. In most cases, such systems need to be installed in separate rooms.

What to look for before buying?

The first thing to consider is volume. It is important to understand how much water will be consumed and at what frequency for the comfortable existence of the whole family. There are averages. So, about 5-15 liters are spent per day per person on personal hygiene, 15-25 liters on dishes, 50-100 liters for a shower, and 150-200 for a bath.

On average, one individual accounts for about 100 liters of water per day. Of course, it all depends on the preferences and habits of the person himself. Someone takes a shower twice a day, and someone is enough and one.

It must be remembered that the larger the volume, the higher the price of the device.

Another important detail in such a water heater is the material from which the inner part is made.

For example, it is better to choose installations whose coil is made of brass. The fact is that this metal has a higher heat conductivity than the same steel. In addition, it is much easier to clean such elements.

The container itself must be protected against corrosion. Cheap options are enameled or glass-ceramic. Expensive models are made of stainless steel.

You also need to remember about the thermal insulation of the entire container. For quality models, this is polyurethane foam or mineral wool. But it is better to immediately reject options with foam rubber.

Connecting to the system

There are two options according to which this hot water boiler can be connected — hydraulic and electric method. The first scheme is considered more effective.

So, two pumps are used at once. The action of one is aimed at heating the room, and the second — to interact with the boiler. In turn, the electrical connection implies automatic switching using a relay.

The two-pump method consists in the movement of flows in different directions. Each individual hot water line is connected in parallel. In this case, the operating mode of the pumps themselves is regulated by a temperature sensor. After each device for creating artificial pressure, a check valve is installed — this allows them to work individually.

Errors during connection

There are several major mistakes that people most often make when buying such units. So, firstly, many people choose a place that is not quite suitable for installation, since the principle of operation of the boiler directly depends on the distance to the boiler or the central heating outlet.

In addition, it is often possible to find incorrect connections to the cold water pipe. It must be connected to the bottom of the unit.

It is also important to maintain a series connection of the inlet and outlet of the coolant, which is the key to efficient operation. Optimal performance can be achieved only when the heating liquid enters the heater from above.

One of the most important points is the connection of the pump, because its incorrect installation entails several serious unpleasant consequences at once. So, the axis should be in a horizontal plane, which will prevent rapid wear of the bearings. It is also important to constantly monitor the strainers that protect the pump from debris.

A water heater with an indirect system is today considered one of the most economical of these units that are used in rooms of any type. They come in different designs and volumes, which allows you to choose the best option.


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