How to fill a heating system with a gas boiler

How to repressurise refill a combi boiler central heating system.wmv

Varieties of Dilution

As mentioned, there are many different ways to style your hair. Each of them has certain properties and differences. Therefore, let’s consider them in more detail.


Here we mean the connection of the pipe with an open expansion tank. The cover that closes it is not airtight and can let air in from the room. It is placed in the highest point, in the attic or under the ceiling of the boiler room.

This scheme is the simplest, but requires constant attention. The liquid evaporates and you have to check the level and refill it regularly. Insufficient amount of liquid leads to air being drawn into the pipeline, which causes an air lock and heating malfunction.

Important! Open two-circuit heating system, the scheme of which is shown below, is the easiest and least expensive in terms of the number of components.


Here the system is built on a similar principle: with an expansion tank. However, this is not an ordinary tank with a lid, but a special tank, inside which there is an elastic partition, a membrane. In one half there is water, in the other half there is compressed air with a certain pressure.

The principle of operation of the membrane expansion tank is. If the water pressure rises (which occurs when the water heats up and expands, which affects the pressure) the water volume expands and fills the water tank with more water. At the same time there is a proportional compression of the “air” chamber.

As a result of the reduced volume, air pressure begins to increase until the water pressure is balanced. When system rarefaction decreases, the diaphragm begins to shrink and the compartment filled with water begins to “push” the coolant back into the pipeline, thereby compensating for the pressure drop.

This construction of the expansion tank ensures that the water keeps pumping until the pressure of the water and the air reaches the same value. In addition, a membrane expansion vessel reduces the likelihood of a sudden pressure drop (water hammer).

Useful at! Water hammer in the heating system is called a sudden change in the speed of the coolant circulation, which occurs when the pipeline is suddenly closed. Increased vacuum affects the integrity of pipes or fittings.

Lower and upper

The difference between these schemes is the location of pipes in relation to each other. For two-circuit heating system with upper distribution implies installation of the pipe that supplies water at the maximum height (above the windows, under the ceiling). “Return”, the pipes that return water to the boiler, are placed as low as possible (along the floor).

Expansion tank for such systems is mandatory. Can be installed as a closed or open (not airtight) tank. The advantage of this scheme of two-circuit heating system is the high speed of the coolant circulation, the disadvantage is that almost half the heat goes upwards (as the “supply” is very high).

When designing a two-circuit heating system with bottom distribution the “supply” is mounted directly above the “return” (in extreme cases. at the level of “under the window sill”). Here high pressures inside the pipeline are not observed, therefore the variant of formation of “air s” is allowed. The problem is solved by installation of the Mayevsky cocks on each floor.

Installation of the expansion tank is possible in any place: in the attic or in the boiler room. The advantage of this method is that the lower wiring is not so “conspicuous”, which is important if the appropriate interior of the room is observed. The minus of the scheme is that it will not be able to work properly without an additional circulation pump (built into the boiler or installed separately).

Horizontal and vertical

Horizontal two-circuit heating schemes. the most popular layout option for single-story country cottages. The advantage of this method is reflected in a whole range of positive qualities:

  • The possibility of disconnecting a separate room from the common branch, which is convenient when performing technical work.
  • Adjust the power of heating in different rooms.
  • To develop the project of a single room individually.
  • Build a room heating on the principle of “underfloor heating”.

Useful at! Two-circuit horizontal heating system can be closed or open. Its scheme can include a conventional or membrane expansion tank.

The vertical distribution is used in cottages with two, three or more floors. The principle of its work is that with the help of a powerful circulating pump, heating fluid flows to the upper floor, where it independently flows down. Thereby it enters all risers and radiators, ensuring an optimal room temperature. The expansion tank is placed as high as possible. For example, it can be an attic or attic room.

Important! Compared to the horizontal layout, the vertical layout is more efficient, since it creates more vacuum, which has a positive effect on the water circulation rate and the rapid heating of the premises.


Two-pipe dead-end (shoulder) schemes. the most popular variants of heating pipes layout for country houses. It represents the following:

  • Assembled from one or more double-circuit branches. The coolant is supplied through one, the return. through the other.
  • Circulation is ensured by an overpressure of 1-2.5 bars supplied by the built-in electric pump installed near the heating element.
  • In the boiler room is mounted expansion membrane tank, which compensates for the thermal expansion of water.
  • The formed air s are removed by the Mayevsky cock on the radiators and automatic valve in the boiler safety unit. Pressure gauge and safety valve are also installed here.

The most popular such a technique is in conjunction with the lower horizontal distribution, where both pipes pass through the batteries in the open.

If it is necessary to divide the coolant into 2 or more parts of a large structure, it is divided into several separate branches, which connect to one riser. A distinctive feature of this scheme is that the length of each pipeline and their heat loads can be different. Specific parameters of these conditions are determined individually and depend on the design features of the house.

Balancing of thermal load of the branches, which differ in length and number of radiators, is balanced. the coolant flow is limited. Regulation stop valves (cocks, valves) play this role. They are mounted on the outlet pipe of the battery or (in some cases), on the entire shoulder.

Tichelmann ring

Arrangement of such two-circuit heating system is similar to the dead-end scheme. The difference between them appears only in a few features:

  • Each of the circuits is enclosed in a separate ring.
  • Radiators are connected as follows: the first radiator from the boiler is the last in the “return. Conversely, the far side in the distribution branch acts first for the return.
  • The heat carrier, in each of the connected pipes, runs in the same direction. From this, the scheme is called the “associated”.

In such systems implies a horizontal bottom layout, which is “hidden” under the floor covering, in rare cases. left open and mounted on the wall. The third option for the location of the ring is pulling on the ceiling slab, which is then hidden by a stretch or suspended ceiling. Pipe branches go down to the radiators.

The main feature of annular “populations” is the perfect hydraulic equilibrium. Important is the fact that the distance “to” and “from” the radiator is the same. This circuit design is able to maintain an almost perfect hydraulic equilibrium. In addition, in the direction to the radiators and back, the water passes the same distance.

Radial scheme

No less popular way of wiring two-circuit heating system in the cottage. This involves the connection of the pipeline through special distribution manifolds. They are connected to the radiators by the shortest possible route (built into the floor or ceiling).

The manifold is installed in the boiler room. Its function is to receive and return the coolant to the boiler by two lines: “supply” and “return”. The temperature is regulated via the adjustment fittings. In addition, the installation of RTL thermostatic headers or servo drives on the valve enables the automatic regulation of room heating parameters.

The water circulates in the opposite direction and the water circulates in the return direction

The principle of operation here is explained by the name of the system itself. In the auxiliary system, the fluid circulates in one direction. A feature of the counter-circulation is the circulation of cold water in the opposite direction to that which it receives from the heating apparatus.

Instead of water

alt=”antifreeze for heating” width=”366″ height=”105″ /Asking the question: what to pour into the heating system of a private house instead of water to improve the performance of the coolant? Antifreeze is often used for this purpose. It does not freeze even at temperatures below zero degrees. Thanks to this property of it, the pipes and radiators will not burst if the room is very cold. If you want to use antifreeze, you should install pipes of small diameter and panel radiators to reduce the required amount of this coolant (it is much more expensive than water).

In addition, filling the heating system with this liquid is troublesome. It can not be pumped from the water supply. And if you use a hose some antifreeze will spill. In addition, if the system is closed, you can not pour the coolant through the tank.

  • Filling from the bottom of the system is done using a manual (pressure) pump, which will contribute to the appearance of the nominal pressure of antifreeze in the pipes. Not every electric pump is suitable. You need a special mechanism that can pump not only water.
  • A long hose is attached to the check valve at the bottom of the system. Near it is placed a large container. The second end of the hose must be raised as high as possible (on the second floor, in the attic) to create increased pressure. After the filling is complete, the liquid is drained from the hose into a prepared container.

How to fill the heating system. types of coolants and rules for filling

After completing the installation of the heating circuit, the question of what and how to fill the heating system becomes relevant. About this, as well as some other details of the equipment of an individual heating system will be discussed later in this article.

Types of coolants

There are several types, mostly liquids, but also occur gaseous. Most often the following two substances are used.

It is a standard filling of the pipeline. It tolerates heat well and does not cause chemical reactions other than metal oxidation. As the circuit is operated, it partially fills with scale that forms as the fluid cools down.

Important! When using this substance, it is sufficient to conduct annual cleaning of the system from solid formations.


Non-freeze liquid is used in systems that periodically turn off, especially in the cold season. It is also useful in the northern regions. When cooling the pipes will not burst, which happens with water. For the infusion of antifreeze it is recommended to create a system with a small diameter circuit, and install panel radiators. It helps to save on fluid consumption.

Antifreeze model ECO-30 on propylene glycol with carboxylate additives, weight. 10 kg, manufacturer. Thermagent.

In addition, it is much more difficult to fill: the antifreeze can not be filled directly with a hose or through the tank (in a closed system).

Pouring is performed in one of two ways:

Filling boiler with water Low pressure How to refill the heating system

  • From the bottom with a pump. It creates pressure, due to which the antifreeze starts to circulate. You will need a special mechanism that can affect liquids other than water.
  • Through the check valve. It is connected to the tank as high as possible. It helps to reduce the pressure. Fill and drain the system after filling is finished.

Preparation phase

As a rule, during the warm period the heat supply structure is not used. Therefore, before you run in a private home heating, you need to make sure the integrity and reliability of its elements and perform a number of preparatory works. Before you use a closed heating system, you need to determine the magnitude of the deviation of its actual performance from the calculated parameters.

According to the rules, the preparation for the heating season is performed in a certain sequence. In the first place carry out a visual inspection of the communications and heating equipment. For the owner of the property should not be the first question about how to start the radiator. First of all, he should make sure that there is no mechanical damage to the body of the device and check the reliability of its connection to the pipeline.

Also, before you start the heating system, carry out a series of preventive measures:

  • Checking the condition of the chimney system. To start the boiler, there must be sufficient draught in the chimney to maintain combustion. For this reason, the internal cavities are cleaned of soot and the integrity of the pipe is inspected. In a brick structure, if necessary, replace damaged elements. Remove any rust from galvanized pipes if any.
  • Visual inspection of pipes. Without this, it is dangerous to start the heating system. You need to find out how tight the pipes, there are no cracks or visible defects.
  • Checking the condition of the batteries. The management company before starting the heating in an apartment building, should warn the residents, and they check the integrity of the radiators. Individual appliances should not be disconnected from the heating system. When filling the pipes make sure the coolant does not leak.

This is a list of rules without which the first start-up of the system should not be done. In order to start the heating season proceeded correctly, it is necessary to carry out a number of activities. The test run of the heating system in an apartment building is done 1 to 2 months before the heating starts. At this time, property owners are better off staying home to make sure there are no leaks.

Liquids of all kinds: Which one is better to use?

Different types of heat transfer fluid are used.

  • High heat capacity. Water will ensure a comfortable indoor temperature, even if it is freezing outside.
  • Low viscosity. Because of this, the pump experiences a minimum load during operation, which guarantees long-term operation of the device.
  • Does not cause health problems for users due to the lack of toxicity.
  • Small coefficient of expansion when heated: only 0.03%/deg. That is why a small size expansion tank is installed in the construction.
  • affordable price.

However, water, along with oxygen, causes metal corrosion, but this is a problem only for metal pipes.


Tosol is a fluid that is used for water cooling structures of car engines. But tosol is also used as a coolant for heating a private home.

  • Low coefficient of expansion when heated: 0,05%/degree;
  • Does not cause rust on the metal due to the presence of anti-corrosion substances in the composition.
  • High per liter in retail stores and from 40 at wholesale.
  • Average heat capacity. In the house with this coolant is not always a comfortable temperature.
  • High viscosity. This puts a heavy load on the pump when it is running and causes the unit to fail.
  • Toxicity. Toxic substances in the coolant have an adverse effect on the health of users.

Propylene glycol

This fluid serves as a base for the production of antifreeze coolant. Its advantages:

  • no toxicity, so the use of propylene glycol is safe for the health of the inhabitants of the house;
  • Low expansion coefficient: 0.05%/ deg;
  • Prevents formation of rust thanks to anticorrosive components.
  • High per liter.
  • Low heat capacity, so the room with this coolant is always cool.
  • High viscosity. This places a strain on the pump during operation and shortens its service life.

Expert-30 Eco Profi coolant, made on the basis of propylene glycol, manufacturer. HimProm43.


Brine of table salt and similar salts are used in heating systems. This coolant is used only in open-type structures.

  • affordable for 1 kg.
  • Low viscosity, so the pump is under minimal strain during operation.
  • Lack of toxicity, which makes the solution safe for health.
  • Small coefficient of expansion: 0.03%/grid.
  • Promotes the formation of rust on the metal in a short time, even without contact with oxygen.
  • Low heat capacity, so brine does not provide uniform heating of the room.

Important! Plain water is recommended for heating systems that are operated during the entire heating season. If the structure is periodically turned off, then experts advise choosing a non-freezing coolant to fill.

Types of heat transfer fluids and requirements for them

In self-contained heating systems for private homes are used liquid coolants of the following type:

This is the most common type of coolant, which has the following number of advantages:

  • Lowest price.
  • Availability.
  • Maximum heat capacity (ability to transfer heat).
  • Low viscosity, and therefore the lowest load on the circulation pump.
  • Low corrosivity. only in the presence of dissolved oxygen.
  • Environmental purity.
  • Small expansion coefficient. not more than 0.03%.

The disadvantages of using water as a coolant are corrosive activity on unprotected steel parts of the system, as well as high crystallization temperature. Therefore, if the house is left at a cold time enough to cool the premises to 0 0 C, the water will need to be drained. Otherwise, under the force of expansion, the freezing water will rupture pipes, batteries and heat exchanger.

Represents an antifreeze for radiators of cars operated in freezing weather. Recently, it is preferred to fill the autonomous heating systems of closed type only. due to the high toxicity of vapor is not used for open circuits. Marked by numbers. 65, 40 or 30. which means the freezing mark of the liquid at temperatures below freezing.

It is characterized by the following features:

How to Repressurise a Heating System with an Internal Filling Key

  • Average Market Price.
  • The index of heat capacity is average, but lower than that of water.
  • High viscosity. which imposes a high load on the pump.
  • Virtually no corrosive activity.
  • Toxic. due to the ethylene glycol in the product.
  • Expansion coefficient. up to 0.05%. nearly twice as high as in water.

Unlike water, brine does not cause corrosion, but this is not always a good thing. So if the heating circuit gets depressurized the fluid will start to leak, while water and other corrosive liquids quickly “heal” the leaks by forming rust.

Non-freezing liquids based on propylene glycol are industrially produced specifically for stand-alone heating systems.

  • Low heat capacity. Almost twice as low as water in its pure form. However, when diluted with water, the index increases to an acceptable level.
  • High viscosity, which puts additional load on the pumping equipment.
  • The coefficient of expansion. not more than 0.05%.
  • Harmlessness.
  • No corrosiveness thanks to additives.
fill, heating, system, boiler

Although propylene glycol is the most expensive in the list of antifreezes, its popularity is high due to its absolute harmlessness. In purified form it can be added to cosmetic and confectionary products.

The product is a solution of simple salts. common table salt, calcium chloride and some others. Used as a budget alternative. to fill the heating system in a private home instead of water. The higher the salt concentration, the lower the freezing point of the brine.

  • Lowest cost. based on the number of salts used.
  • Sufficient heat capacity. 2/3 of the indicator for water.
  • Minimal viscosity.
  • Expansion coefficient. 0,03%.
  • No toxicity.

The main disadvantages are low fluid mobility with a high concentration of salts and high corrosiveness to the walls of the metal elements of the system.

Selection requirements

The fluid to be poured into the heating system as the heat transfer medium must comply with the following set of requirements:

The parameter describes the amount of heat energy which must be supplied to 1 kg of the substance in order to raise its temperature by 1 0 C. For heating fluids in heating systems, this index must be as high as possible. Conventional water has the highest rating of all other fluids poured into the circuit.

Each individual heat transfer medium has its own characteristic operating temperature range. Failure to observe these conditions can result in damage to the equipment or irreversible loss of performance of the heat transfer medium.

For example, water expands when it freezes and tears the pipes or radiators that hold it. On the other hand, organic coolants decompose when heated above 100 0 C into separate components, losing their original characteristics forever.

The chemical activity of the coolant can cause rusting of the metal parts of the circuit. The problem can be solved by inhibiting additives. For this reason many coolants contain special additives.

However, the problem most often appears when the coolant is in constant contact with oxygen, and is virtually absent when dissolved gases are removed from it.

This is especially true for conventional water. once saturated with air bubbles at the point of contact. the expansion tank. it more actively corrodes steel pipes, radiators and other elements. Therefore, only for heating systems of closed type allowed to fill any type of coolant. In addition, they are most often equipped with plastic pipes that are inert to corrosion.

The viscosity index determines the degree of internal friction and, therefore, fluidity. It in turn affects the pumping speed. Therefore, the greater its value, the more energy is needed to move the coolant through the system.

The benchmark for minimum viscosity is water. All other heat transfer fluids used in stand-alone heating circuits have a large value of its value, and therefore have worse flow characteristics.

Modern heating systems include a range of equipment in which the thermal fluid also serves as a lubricant. It is not only a circulating pump, but also make-up and emergency shutoff valves, thermostat, sensors of protocol, pressure, etc. Therefore, it is necessary to select the liquid also on the basis of its lubricating ability indicators according to a specific type of system.

The substance used as a coolant in domestic heating systems must be completely safe for the environment. It must not be used in a vaporous state, as a breakthrough due to the high temperature can cause burns.

Also the antifreeze must not be toxic as, for example, compositions with ethylene glycol. Therefore, for this number of reasons, domestic heating systems are most often filled with water.

The components of the thermal fluid must not come into contact with the components of the heating circuit. For example, if the heating system of a two-circuit boiler with steel radiators is filled with ethylene glycol, the internal zinc coating of batteries will quickly thin.

over, heating the coolant to the standard 80-90 0 C will lead to a loss of its basic properties. the fluidity becomes higher than that of water. Over time, this will inevitably lead to leaks in various joints with seals based on rubber, paronite and other polymers.

Filling heating radiators

Starting with a radiator heating system. Turn on the pump, bring the pressure to two atmospheres and go bleed air from the radiators. The air must be started at the lower level, because all the air from the lower floor ends up at the top, but it is not sucked back down again.

The air is expelled very simply, through the Mayevsky cocks. You can take a normal slotted screwdriver and open the Mayevsky tap by the slot. This is how to get the air out of the cocks. The air is blown out of all radiators, convectors usually do not need to be blown out. It flies away from there by itself, because there is no way it can stay there for a long time.

After the air is deflated, the pressure in the system drops, and you need to raise it again to two atmospheres. Then go back and bleed the air out again. Then you can turn on the boiler. It’s usually 60 degrees. And we go through all the radiators, checking if there are any idle ones.

If the radiator is warm at one end and cold at the other, it means that there is air in it. We remove it using the same method. If the radiator is completely cold, this problem is also easily solved. All radiators that work are closed, and the pump has nothing to do but pump the coolant through the pipes to the last radiator.

fill, heating, system, boiler

After that it is necessary to bring the pressure in the boiler to normal and by ear to determine the work of the pump. If you hear periodic air bubbling through the impeller, and when you open it you find foam coming out, you need to get rid of it.

Turn off the pumps and allow the foam to stand for about 15-20 minutes. It is especially important to do this on systems with antifreeze. Foam turns into an air bubble. After that we start the system again and catch this air on the radiators. This completes the filling of the heating system

Acquisition of a gas boiler

When buying, you should choose an organization that is not only engaged in the sale of boilers and related equipment, but also their installation. This approach allows:

  • Get expert advice not only when buying, but also when installing, debugging and operating the equipment.
  • Be confident in the quality of the boiler and its service (timely supply of spare parts).
  • Be sure that there are no problems with the warranty (which may occur if the installation was carried out by an outside contractor).
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