Boilers and pipes: we install a heating system in a private house

Heating is one of the most complex engineering systems of a private house. However, with some skill and experience, you can mount it yourself. The main thing is not to rush and carefully delve into the intricacies of each stage. We will understand the details of the selection and installation of equipment.

Choosing a heating scheme
With forced or natural circulation
In a natural circulation scheme, water moves through the system under the influence of convection, by gravity. The boiler in such a system is located at the lowest point of the house. Heated water, being lighter than cold water, rises. It passes through the radiators and, cooling down, goes down into the boiler. When using a non-volatile boiler, such a scheme will work even without electricity.

However, such a system has a number of disadvantages.

The thinner the pipe, the stronger its resistance to water flow. Natural circulation will not go through thin pipes. Calculating the optimal diameter of each heating section is not an easy task.
The diameter of the pipes will be much larger than for a system with artificial circulation. Consequently, the cost of material will increase several times.
When installing a system with natural circulation, the slope of the pipes must be precisely maintained.
The house will warm up slowly. The reason is the large volume of the coolant and the low speed of its movement.
Non-freezing coolants have a high viscosity. They cannot be used in systems with natural circulation.
In houses with warm floors, the system cannot be used.
It is much easier and cheaper to provide energy independence with a UPS or a generator . Therefore, systems with natural circulation are rarely used today.

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In a forced circulation system, water is moved by a circulation pump .

Single pipe or double pipe
In a single pipe system, all radiators are on the same pipe. The coolant passes through them sequentially. An obvious disadvantage of the system: the last radiator in the chain will always be colder than the first. This can be corrected by installing a more powerful circulation pump. But this leads to increased energy consumption and still does not allow to completely equalize the temperature in the system.

In a two-pipe system, each radiator is connected to two pipes – inlet and outlet. Heat losses in the pipes are minimal, so the temperature in the radiators is approximately the same. However, such a scheme doubles the cost of the pipes themselves.

Beam scheme
Both single-pipe and two-pipe systems can have multiple circuits. This reduces the inertia of the system and equalizes the temperature on the radiators.

In larger systems, radiators further away from the boiler will be colder (even when using a two-pipe scheme). The beam scheme eliminates this problem.

The ray scheme has another advantage. It allows you to adjust the flow of each circuit: you can maintain different temperatures in different rooms. For example, lowered in the basement and hallway, increased in the nursery and normal in the rest of the house.

For the device of the beam scheme, an additional element will be required – a collector. You can buy ready-made, you can assemble on cranes.

Selection and installation of the boiler
The boiler is the heart of the heating system. His choice should be given special attention. To choose a suitable model, you need to accurately calculate the power of the boiler (how to do this is written here ).

A gas boiler
Before installing the boiler, make sure that all distances to building structures are maintained.

For wall mounting : minimum 0.5 m from the ceiling, 0.3 m from the floor, 0.2 m from the side walls and 1 m in front of the front panel.
For floor : at least 70 cm to the walls from the side and rear walls of the boiler and at least 1 m from the front.
Any gas boiler should be installed only in full accordance with the project of the licensed organization, which was approved by the gas service. Connecting the boiler to the gas pipeline and starting it can only be done by specialized organizations. Violation of these requirements will lead to fines and disconnection of the home from gas.

Install the boiler in accordance with the instructions and with the gas project. A wall-mounted boiler often comes with a mounting template. For convenience, it can be fixed on the wall with tape.

For a boiler with a coaxial chimney, you need to prepare a hole for the chimney. Mark it in accordance with the documentation for the boiler. When making a hole, provide a slope of 2-3º outside the building – for the outflow of condensate from the pipe.

A boiler with an open combustion chamber is connected to a house chimney, the pipe is led out above the ridge of the building. The cleaning hole should not be above the boiler or other elements that will make it difficult to clean the chimney.

Do not install the boiler on a wall or floor made of combustible materials.

When installing a floor-standing boiler on a wooden floor, a refractory base must be provided under it. It is made of concrete or special slabs with a thickness of at least 100 mm. When fixing the wall-mounted boiler to a wooden wall, it is necessary to protect it with a sheet of steel. The sheet must protrude at least 100 mm on each side of the boiler.

electric boiler
The requirements for installing electric boilers are less stringent. A project for the installation of an electric boiler is optional. As a rule, it is not required to obtain approvals from state bodies. However, some recommendations are desirable to follow.

It is better not to put the electric boiler in a bathroom, bathroom or other room with high humidity.
Connect the power supply to the boiler through an RCD (residual current device). Without it, when the heating element burns out, all the batteries in the house will be energized.
When fixing the boiler to a wooden wall, install a non-combustible material under it.
Comply with the boiler installation requirements specified in the user manual.
Make sure the wiring is rated for the current drawn by the boiler. The maximum power for each wire section is given in the table.

So, for a boiler with a power of 10 kW, the cross section of the conductors with a single-phase connection must be at least 6 mm 2 , with a three-phase connection – at least 1.5 mm 2 .

Also check that the cross section is maintained along the entire length of the wiring up to the introductory machine itself. Of course, all intermediate devices (automatic devices, RCDs, circuit breakers, etc.) must be rated for the boiler current.

If you can connect to both a single-phase network and a three-phase network, you should choose the latter. This will reduce the load on a single-phase household network and reduce the risk of interference and drawdowns in it.

Boiler piping
Some elements of the system are mandatory for installation. This is a security group and a filter.

The safety group includes three elements: a pressure gauge, an air vent (plunger) and a relief valve. It is placed immediately at the outlet of the boiler. The pressure gauge shows the pressure of the coolant – usually it is set at 1.5-2 bar. The air vent removes gases trapped in the coolant. A relief valve (usually set to 3 bar) protects the boiler from bursting when boiling.

There is an opinion that for modern boilers with temperature sensors, a safety group is not needed. This is not true. The temperature sensor in the boiler may not be in the zone of maximum heating. In thin heat exchangers of wall-mounted boilers, the temperature rises very quickly. If for some reason the circulation of the coolant stops, the temperature sensor may not have time to turn off the boiler. The absence of a security team in such a situation will lead to an explosion.

A mud filter is installed at the boiler inlet. It protects the heat exchanger from debris, scale and rust from the heating system. During installation, dust and chips may remain in the pipes. Dirt is often found inside new batteries. In the absence of a filter, all this can clog the boiler heat exchanger.

Keep in mind that the dirt filter needs to be washed regularly. It is more convenient to do this on self-cleaning filters – you just need to open the tap under the filter.

Pressurized water will wash the accumulated dirt out. The usual “oblique” filter is much cheaper than a self-cleaning one, but less convenient. To flush it, you need to unscrew the plug, take out the mesh, clean it, insert it back and screw the plug back.

It is strongly recommended to install ball valves at the inlet and outlet of the boiler. They will allow you to repair or replace the boiler without draining the entire coolant. And at the same time, it will facilitate the washing of a conventional mud sump.

Elements of the heating system and features of their installation
Domestic heating systems use pipes made of different materials: steel, copper, polypropylene, etc. But not everyone is suitable for self-assembly. Pipes made of steel and stainless steel are difficult to mount (welding, turning with a pipe bender, threading). Copper pipes are a little easier to install, but this is an expensive “elite” solution. It is unlikely that anyone will mount them on their own. Metal-plastic, which was often used for heating in the past, is not the best option. So that leaves three types.

Corrugated stainless steel. It is resistant to rust, withstands high temperatures and pressures. Installation is simple, the price of pipes is low, but the fittings are expensive. In addition, the uneven inner surface creates additional resistance to flow. This must be taken into account: either increase the diameter or increase the pump power. With an open gasket, they look unaesthetic.

Installation of such pipes is the easiest among all “home” types. It does not require any special tools. The fitting is simply screwed onto the end of the pipe and clamped with two keys.

Reinforced polypropylene. The most common option for heating a country house is due to its low price and ease of installation. The pipes are straight, their neat installation looks aesthetically pleasing. But in systems with high pressure and temperature, polypropylene cannot be used (95º C and 3 bar maximum). In addition, the reliability of connections for PP pipes is lower due to the risk of hidden defects during installation. It is not recommended to embed in non-separable building structures.

For installation, you will need special pipe cutters and an iron for welding PP pipes with nozzles of different diameters . Installing the fitting on the pipe is quite simple. You need to heat both parts in the iron, then quickly connect them.

The time of heating and holding the welded parts in a stationary state must be strictly observed for different pipe diameters.

Overheating will cause the plastic to collapse into the pipe, thereby narrowing the diameter of the connection. The resistance to flow increases, noise appears.
If the connection is underheated, there is a risk of leakage – maybe immediately, or maybe after a couple of years.

Cross-linked polyethylene. The pipe itself is cheap, but the fittings are more expensive than those of polypropylene. It is easy to install, but the pipes are bent, it is difficult to straighten them completely, so the open installation will look sloppy.

For installation, special tools are required – an expander and pressing pliers with nozzles for different pipe diameters. To install the fitting, put a sleeve on the pipe, expand the end of the pipe, insert the fitting into the pipe and push the sleeve onto it with pliers.

The connection is more reliable than in the case of polypropylene pipes.

Heating radiators are not enough to choose correctly, they still need to be installed correctly. Otherwise, their effectiveness will be low.

Each radiator will require an installation kit – a Mayevsky crane, a plug and a set of couplings. Couplings are needed because the threads on the radiator sections are usually 1″ or more, and the coolant is supplied through pipes DN 20-25 mm, for which it is more appropriate to use fittings with a ½” or ¾” thread.

There are several ways to connect radiators based on the use of convection and the combination of convective currents with the direction of circulation.

The most efficient way to connect is the first one. The second and third are less effective. The third method is not recommended for use on long radiators (the length of which exceeds the height by one and a half or more times).

Other connection options will create high flow resistance.

Radiators are traditionally attached to the wall or floor under the windows. This is done so that the flow of warm air from the batteries cuts off the cold zone by the window from the rest of the room. For free flow of air along the radiator, install it at some distance from the walls and floor.

Circulation pump
The circulation pump provides circulation of the heat carrier. Its performance must be properly selected in accordance with the parameters of the system.

The circulation pump is placed at the inlet or outlet of the boiler immediately after the shut-off valves. You can choose any option: the difference in flow and return temperatures for “hot” circulation pumps is unimportant. But when installed on the return line (inlet), the mud filter should be installed in front of the pump – otherwise all the dirt will go through the circulation pump.

Expansion tank
The expansion tank compensates for the thermal expansion of the coolant in a closed heating system and maintains a stable overpressure in it. Increased pressure in the system is necessary for the efficient operation of air vents and the removal of gas bubbles from the coolant.
How to properly position the expansion tank in the heating system? The main rule: the vacuum section between the tank and the circulation pump must be reduced to a minimum. This will reduce the likelihood of air leaking into the system if the pressure suddenly drops.

Other elements
These, of course, are just the highlights. In complex systems, additional elements are used – their installation requires a separate description.

reducer for automatic feeding of the heating system with water;
collectors for organizing a radiant heating scheme;
hydraulic arrow for distributing the coolant between several circuits with separate circulation pumps;
collectors and three-way valves for underfloor heating;
floor heating pipes ;
indirect heating boiler.