Schemes for connecting a water heater to a water supply system: how not to make mistakes when installing a boiler

Alexey Dedyulin
Checked by a specialist: Alexey Dedyulin
Author: Victor Kitaev
Last update: April 2024

The installation of a water heater will provide owners of country houses with hot water, increase the comfort of apartments from the old housing stock such as the Khrushchev and small-family dormitories. An indefatigable unit will be hardworking to prepare and supply water to the taps, so that the owners enjoy the benefits of civilization.

So it will be, if the connection diagrams of the water heater to the water supply system are strictly followed, agree? Full answers to a wide range of questions arising before installing water heaters and in the process of including them in a communication network can be found on our website.

Reliable information will be useful to independent masters who want to carry out installation with their own hands. It is also necessary for customers of plumbing services to check the quality of work.

The article describes in detail the types of water heaters, their design differences are indicated, the specifics of the connection are indicated. Valuable tips are provided to ensure that the equipment works perfectly after installation. The information content of the proposed material is perfectly complemented by photo images and video recommendations.

Types of domestic water heaters

Features of connecting household heaters are directly related to the types of devices, their technical parameters, and overall dimensions.

Traditionally, two type of heaters:

  1. Cumulative.
  2. Flowing.

Both types of boiler systems differ from each other in heating technology.

Accumulative domestic water heater
The device of the accumulative type equipped with an electric heater (TEN). Such equipment is most often used in the domestic sphere. It can be mounted directly in the bathroom, if the overall dimensions allow

Storage heaters cold water is collected in a tank, heated and then discharged to the drawdown.

Flow units heating is carried out directly during the flow of cold water in contact with the heater, without collecting liquid in the storage tank.

Consumers in the domestic sphere mainly use storage boiler systems. A comparative review of both types of water heaters is given in this article.

Technical device for storage boiler

A storage-type water heating system, boilers, in a simplified diagrammatic form, is a tank equipped with electric heaters or liquid heat exchangers. The storage vessel has pipe lines for the supply of cold water and the output of hot water.

Indirect heating boiler
More powerful and volumetric design - indirect heating installation. It is clear that in this case the source of heating energy is water coming from the heating system. However, if desired, it is possible to connect electric heating

Constructions indirect heating boilers additionally equipped with a coolant working area and heating connection lines.

Any modern system, regardless of design features, is equipped with automation, due to which the temperature of water heating is adjusted and the system as a whole works.

Structural design of heaters

Exist storage boiler designs designed for installation vertically (wall) and horizontally (floor). Of course, in each individual case of the use of certain boilers, there are their own mounting features.

So, if wall mounting of a water heating device is supposed, a preliminary calculation of the load and comparison of the results with the design parameters of the wall of the room on which the device is to be mounted is required.

Flowing boiler household
Recently, instantaneous water heaters are rapidly gaining popularity. Users are attracted by their small size, the possibility of a simplified easy installation. Really convenient devices for small water consumption needs

Installation of equipment without load calculations threatens to result in a fatal installation error, when a filled boiler can simply collapse along with the flimsy partition on which it was mounted.

According to the instructions for the equipment, the load must be calculated taking into account the fourfold weight of the boiler system.

Therefore, if the structure of the supporting wall is frankly weak, the water heater circuit needs to be supplemented not only with lines for connecting to the water supply and coolant, but also with reinforced posts - through fasteners.

Horizontal water heater
Horizontal boiler plant used for local hot water supply. It also provides for electric heating and in this installation option an expansion tank is installed, which is the right solution

On the classic wiring diagrams for wall-mounted boilers, the inlet / outlet pipes of the heating apparatus are marked with the corresponding color - blue / red.

Wiring diagrams and solutions

You can connect a heating device to a centralized supply in one of two ways: through a security group or directly.

A security group consists of a set of the following elements:

  • shut-off crane;
  • Check Valve;
  • safety valve;
  • expansion vessel.

Option number 1. The presence of a safety group is traditionally used in indirect heating boiler plants, as well as when centralized system pressure above the boundary parameter of the operating pressure of the boiler.

Installation diagram for boiler with safety groups
The classic scheme of indirect heating equipment. Two safety groups are used: 1 - boiler safety group; 2 - an expansion vessel; 3 - safety group of the boiler; 6 - heating circulation pump; 7 - boiler circulation pump (+)

Option number 2. Direct connection is usually applicable to equipment of small capacity, with a flowing principle of operation.Direct connection is also allowed under conditions of lower and more stable centralized water supply pressures. The wiring diagram in any case involves the installation of shut-off valves.

Location of fittings at the inlet and outlet
In order to be able to carry out conservation and repair of water heating equipment, it is equipped with shut-off valves at the inlet and outlet of the system (+)

Criteria for error-free installation of equipment

Among the main moments of installation, on which attention should be paid so as not to make mistakes - this is the correspondence of the diameters of the pipelines with respect to the inlet fittings, as well as the cross-section of the cable supplying the boiler electric heater.

The diameter of the supply pipes should provide a free flow of water along the inlet / outlet lines. Therefore, a larger diameter of the sleeves with a transition to the size of the fittings is still acceptable, but the cross-section of the pipelines is smaller than the inlet pipes of the boiler, it is already seen as a gross error.

Proper boiler connection
A good example of equipping a boiler installation of electric heating with all the necessary fittings. It is also worth noting here the qualitatively (accurately) made insulation of all suitable and outgoing lines

The cross section of the supply cable is similar. A cable of a larger section is not prohibited, and a cable of a smaller section is strictly prohibited.

True, the cable increased against the norm of the cross-section creates difficulties when laying in the channels, takes up more free space. It seems logical here that the exact wire section selection depending on the load current.

The power outlet is usually mounted directly on the unit. The height of installation of the outlet from the floor level is not less than 1.5 m. Household boilers are designed for power supply by single-phase alternating current 220-250 W. The current load is usually not less than 10 A.

Electric boiler connection
Connection of the boiler system according to the electric circuit. Such a variant of the compounds can be considered made faultlessly. The wire cross section is as specified in the documentation, the ground circuit is present

The exact value is determined by the performance of the heater and is indicated in the technical documentation. It is to the specified current value that it is necessary to select a circuit breaker.

For example, for flow heaters, the following current cutoff standards for automatic machines are relevant (table):

Boiler power (flow diagram), kWCutoff current, A
3,520
5,525
6,530

As a rule, all required connection parameters are specified by the boiler manual. The user manual accurately explains all the points of installation. Therefore, it is recommended that you carefully study the documents that are included with the machine before installation.

Some features of the water supply circuit

Connecting the storage boiler. Cold water is supplied to the boiler system through a piping line that connects directly to the centralized riser.

At the same time, a number of components necessary for the normal functioning of the equipment are mounted on the cold water line:

  1. Stopcock.
  2. Filter (not always).
  3. Safety valve.
  4. Drain cock.

These circuit elements are installed in the area between the cold water supply pipe and the boiler in the marked sequence.

The heated liquid outlet line is also equipped with a shut-off valve by default. However, this requirement is not mandatory, and if the faucet is not supplied at the outlet of the hot water supply, there is no serious error in this.

Features of connecting a water heater to the cold water
All water heater connection schemes have common features. The cold water supply point is located below, filters and a gearbox must be installed in front of it to reduce the flow pressure (+)

Connection of instantaneous water heater. Compared to the storage boiler, the work is carried out according to a simplified scheme. It is enough to install only one stopcock in front of the inlet fitting of cold water.

But the installation of a shut-off valve at the outlet of the hot water supply of a flow heater is regarded by many manufacturers as a gross installation error.

It should also be taken into account: if a well, a well, a water tower, etc. acts as a source of cold water for a flowing water heater, it is recommended to turn on in series with the tap (after the tap) coarse filter.

Often, a mounting error with connecting a filter or failure to install it will void the manufacturer’s warranty.

Frequent installation errors for water heaters

The rules for the installation of such equipment provide for the use of insulation on the HVS / GVS pipelines. At the same time, the technical requirements for installation determine the minimum possible size of the insulation thickness - 20 mm.

The thermal conductivity of the insulating material must be at least - 0.035 W / m2.

Isolation of boiler water lines
An example of insulation of a heater system, where obvious errors are noted. It is necessary to isolate not only pipes, but also working components installed in the pipeline section. Modern insulating materials make this easy.

When installing water heaters, they often violate the connection scheme of the home unit to the water supply, using insulating material of small thickness, or do not use insulation at all.

As a result, when the full operation of the device begins, significant losses of thermal energy are noted. These losses are reflected in the heating time, which increases significantly.

Improperly made or missing insulation is the main cause of condensation on the cold water line. This state of the system reduces the level of user comfort, contributes to the formation of an unsanitary environment inside the premises where the equipment is located.

A common mistake should be the installation of a boiler without an expansion vessel. The scheme where the introduction of the expansion vessel is envisaged is relevant specifically for storage-type water heaters.

Thanks to the expansion vessel, it is possible to compensate for the increase in pressure caused by the increase in the volume of water in the boiler storage.

Expansion vessel on the boiler
Installed expansion tank in the indirect heating system. In fact, the installation of the expansion vessel failed. This element of the system should be located above the line of the upper cover of the boiler. In addition, there is no pipe insulation.

As a rule, the installation of storage heaters is limited to the inclusion of a safety valve in the area of ​​the cold water main. Such a peculiar replacement of the expansion tank with a safety valve is permissible, but, from the point of view of proper installation, this is a technical error.

In fact, an expansion vessel with a non-return valve must always be installed on storage boilers.

List of other installation errors:

  • the electric cable is laid on sharp metal edges or on surfaces with high temperature;
  • the order of connecting the trunk lines does not correspond to the order indicated in the diagram;
  • the installation level of the water heater relative to the horizontal and vertical is violated;
  • there is no ground loop of the water heater;
  • the parameters of the electric network where the equipment is connected do not meet the passport requirements;
  • installation is carried out in a room where there is no water supply and sanitation system.

Any, even insignificant error in the installation of water heating equipment can play a fatal role after the start of operation of the device.

We offer you to familiarize yourself with detailed installation instructions for a storage and instantaneous water heater:

  1. Do-it-yourself water heater installation: a step-by-step guide + technical standards
  2. DIY instantaneous water heater installation: step-by-step instruction

Conclusions and useful video on the topic

The operation of the hot water supply and the heating system depends on the correct installation of the water heating devices, so it is important to take into account all the installation nuances. A few practical tips are presented in the videos.

Professional advice:

Recommendations for self-installation:

It is always recommended to carefully monitor the progress of installation work, being guided by the parallel documentation attached to the installation of a specific boiler model.

Often, users mount the system without bothering to look at the attached circuit. Connect two water tubes and insert the plug into the outlet - such actions for them seem to be commonplace. But the technique of mistakes does not forgive.

Do you have personal experience installing and connecting a water heater? Want to share your knowledge or ask questions about the topic? Please leave comments and participate in discussions - the feedback form is located below.

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Visitors Comments
  1. Sergey

    A couple of years already has a storage tank of 20 liters. Hanging on the wall, connected it himself with the help of his brother. This is my second experience. I myself incorrectly connected the first heater without an expansion vessel, so due to pressure and improper operation in one day it just started to wildly flow, I had to urgently change it. If you yourself are not sure, it is better to call at least someone with installation experience.

  2. Vladimir

    Last month, as we always have in the summer, we had to turn off hot water. The announcement hung, we were mentally prepared for this. But on the planned day, water from the hot tap continued to flow at normal temperature. We did not become indignant ... After talking with the neighbors on the site, I found out that they did not have hot water! We discussed why it was flowing with us - and a neighbor said that most likely someone had a wrong installation of a water heater in our riser, and he supplied the entire riser with hot water. We plan to buy and install our heater this month. Tell me, how can I not follow the path of the neighbor who screwed up the installation? What to look for? I’m not greedy, but I don’t want to pay for heating all the neighbors in the riser ...

    • Expert
      Alexey Dedyulin
      Expert

      And why do you need to install a boiler for heating water, if now the neighbor supplies free? Just kidding, of course, sooner or later this "holiday" will end.

      Most often, the reason that people supply their neighbors with hot water for free is an inset into the current hot water supply. At the same time, people forget to close the valve, which blocks the flow of water. Accordingly, after connecting the heating boiler, the flow of hot water in the opposite direction begins.

      If there are several such valves, then all of them must be closed. Moreover, it happens that it is impossible to do (the design is outdated), then you just have to brew or change the valves to working ones. The latter option is relevant if you plan to use hot water from the boiler room in winter, and from your boiler in summer.

  3. Gregory

    My biggest mistake when installing the boiler is not to install a water drain valve on top of the return pipe.This is really sad, especially when it is time to change the anode or heater or all together, you have to unwind the connections and drain the water while standing with a bucket for 30-40 minutes, while the boiler is 50 liters. Now, don’t do that. And the rest of the installation does not cause certain difficulties.

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