Filling the heating system with coolant: how to fill with water or antifreeze

Every year, at the end of the heating season, the autonomous water circuits, which diligently supplied the owners with heat, are freed from water or antifreeze replacing it. With the onset of the first cool days, the heating system is again filled with the coolant necessary for its operation.

With the order of performance of this difficult work and the necessary equipment it is worth getting acquainted in order to avoid mistakes.

How to fill the heating circuit with water

Due to fluidity and high heat capacity, heat transfer fluids from the boiler to consumers are used, among which water takes the first place.

It is used to fill even the most capacious heating systems. It is generally available and inexpensive, which determines the widest range of applications.

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The reasons for filling the heating circuit
The reasons for filling the heating circuit
Specificity of the choice of the heat carrier
Specificity of the choice of the heat carrier
Equipment to speed up the filling
Equipment to speed up the filling
Expansion Crane
Expansion Crane
Crane in front of the circulation pump
Crane in front of the circulation pump
Providing free access to the boiler
Providing free access to the boiler
Mayevsky's crane and ball valves
Mayevsky's crane and ball valves
Automatic air vent on the riser
Automatic air vent on the riser

As pumped from natural reservoirs or wells, and tap water has many impurities and mineral inclusions. When boiling, the impurities are scaled on the walls of the boiler and form growths similar in composition to the pipes. These deposits are extremely harmful to systems with the latest modifications of heating units. Therefore, the water must be pre-cleaned, boiled or, if funds allow, to purchase distillate.

The second lack of water is the ability to contain oxygen, which is corrosive to metal. Due to the high salinity, coupled with oxygen released during heating, water is not recommended to be changed in heating circuits more than once a year.

The weighty advantages of water as a heat carrier are optimum viscosity and heat capacity. It accumulates and gives off heat better than antifreeze by 15-20%.Inferior to them in fluidity, so that it does not leak through the seals of detachable joints of the system, in viscosity, thanks to which it moves faster through the pipes.

Water as the heat carrier for autonomous systems of heating
The most popular and widely used type of coolant for heating systems is water that attracts low cost and accessibility.

Calculate the amount of coolant to fill

To correctly fill your own heating system with water, you need to determine it will be required in liters. The volume of coolant without any problems, you can calculate yourself. To do this, add up

Vsyst heating= Vboiler+ Vexpansion tank+ Vradiat+ Vpipes 

The useful volume of the boiler is usually indicated by the manufacturer in the technical documentation for the equipment produced by it. Spacious sectional radiators too. If such information cannot be found, then there are averaged indicators:

V of one section of the radiator depending on the material of the body:

Table with average volume of radiator sections
The table shows the averaged data on the volume of water in the radiators. The actual volume will differ depending on the dimensions of the heating device.

The total volume of the radiator is found by multiplying this number by the number of sections.

Vexpansion tanka closed type is selected before purchase so that its useful volume is equal to or slightly exceeds the volume of water, taking into account thermal expansion. This parameter must also be known.

Calculation of the volume of the expansion tank
According to a simplified scheme, the volume of the expansion tank of the membrane structure is calculated by multiplying the volume of water in the system by a factor of 0.03 (+)

For open-type heating systems with an expansion tank communicating freely with the atmosphere, the volume is taken according to the actual dimensions.

Volume in pipes:

V pipes = 0.786 × D2× L

where D is the internal diameter of the pipes, L is the length of the pipes.

The volume of the system will then be equal to:

V systems = V pipes + V boiler + V expansion tank + V consumers.

Where V consumers are the sum of volumes, boiler and other devices. Their volumes can be found in the technical documentation or calculated. The calculated volume is tedious to increase by 15 -20 percent, i.e. multiplying by 1.15 or 1.20.

Table with calculated volumes of water in the pipes
The easiest way to determine the volume of water in the heating pipeline will provide a table with the already available data (+)

A more laborious way is to fill the system with tap water and then drain it, measuring the volume with a meter or measuring containers.

Tap water is sometimes used, but this greatly reduces the heating time. Saving the ruble, we lose thousands. In this case, it is better to pass water through special membrane or chemical cationic filters.

To fill the heating, we also need transition hoses and a pump for pumping fluid.

Dependence of the pouring technique on the cause

The reasons for filling affect the sequence of work. If this is a new system, then we check it visually and conduct tests, pressure testing with overpressure, pumping air or liquid at about 2-2.5 atmospheres (the norm is 1.25 part of the working pressure, but not less than 2 atmospheres). On the manometer we control the absence of pressure drop.

For filling small heating circuits, you can take an automobile pump instead of a compressor. Sometimes they perform pressure testing directly with a liquid, using a centrifugal pump, having previously connected the expansion tank to the system. For small volumes, a hand pump with a liquid compartment can be used.

How to fill the coolant in the heating system
For filling a small heating circuit with a heat carrier, it is better to rent a hand pump with control devices for the state of the system being filled.

If we carry out periodic cleaning of the system with the replacement of water, then it is necessary to first drain the liquid, preparing a place or container for it. Waiting for the coolant to cool, we release excess pressure by unscrewing the nipple. At the top point, open the valve or Mayevsky valve to communicate with the atmosphere. At the lowest point, gradually open the drain valve. With a sharp opening, water hammering occurs, leading to damage. Here you need to be careful.

Drain the coolant, fill the system with flushing fluid and circulate it with a pump.

Why do I need to flush the heating system
Washing with chemical additives dissolves scale, precipitation and rust, the pieces of which are sifted through the filter and are deposited in the storage tank

Then it is washed with pure water with additives and a neutralizer designed to neutralize the additives of the first washing.
After these operations, as in the first case, the heating is crimped. Identified leaks and weak spots are usually in the field of welding and threaded connections.

Cast iron batteries are equipped with connecting gaskets, which eventually dry out, grow coarse, and leak during cooling.They should be replaced and carry out additional tightening of the batteries. After the repair work, again the pressure test and, with a positive result, proceed to the next stage.

Pressure testing before filling the heating system with coolant
Repeated crimping of the autonomous heating network ensures that after the flushing and other operations, the circuit has remained in working condition.

Heating is filled with water through the bottom point with the top open. Having connected the electric pump, we pump water through the tap into the system. Moreover, the valve is open half or less to prevent water hammer. Gradually, the system is filled, which confirms the noise from the movement of water and a slight gurgling. We finish when water begins to flow from the top point.

Then we begin to bleed the air from the connected consumer appliances, boiler, boilers, expansion tank with a membrane and batteries using existing valves and valves. Next, we connect a transparent hose to the top of the system, which we lower into a container with heat carrier. After switching on the pump, we additionally fill the heating until water flows out of the transparent hose in the tank without air bubbles.

If possible, after, you can loop the injection system with a hose, and drive the coolant several times. This will provide additional degassing. Finally, air is pumped up behind the expander membrane, providing the necessary pressure for the heating circulating pump to operate, which we turn on to run without heating.

For a complete check of the quality of filling the system, it is necessary to turn on the heating and by heating in a trial order, determine the absence of air plugs and the uniformity of heating using a thermal imager or an infrared temperature meter.

Stages of refueling with a heating system
At the end of the work it is necessary to check the temperature supplied by the heating system. The initial temperature of the coolant must be such that the building can warm up.

At the same time, with the help of cranes or modern thermostats, installation and adjustment of temperatures in the rooms is carried out. Evaluated and the effectiveness of thermal insulation. It is necessary to provide a reserve of purified water and means of its topping up into the system, in order to exclude evaporation losses. All these actions are designed to ensure trouble-free operation of the heating for the winter period.

Rules for the implementation of heating water

Recently, not only in private houses, but also in apartments began to arrange individual heating. Usually install double-circuit boilers with a feed module. And it will be easier to learn how to make a recharge yourself than to call the master for this:

  • Open the tap at the bottom of the boiler, then at the top of the system, the air release valve and with the appearance of water close it and the make-up tap.
  • We turn on the boiler and if the murmur and gurgling is heard in the pump, then we remove the outer casing from the boiler and find it.
  • We weaken, but do not unscrew the screws with a screwdriver, to bleed air from it until moisture appears. The pump has a cover screwed for this. Although the instructions say that these boilers have automatic air venting devices, they cannot remove it all.

Especially during the first start-up of heating, it is necessary to gradually and gradually heat the coolant to prevent damage from water hammer. You can not immediately turn on the boiler at full capacity. When stopping heating, it is also important to slowly lower the temperature.

This is especially important for long heating networks, which have a significant deformation, thermal expansion.From this expansion, or compression, by retaining fasteners or shapes, stresses are generated that are discharged spasmodically, imparting a shock to the fluid.

Fluid, depending on the flow areas, can increase the force of an impact and cause destruction elsewhere, usually at bends. And if a resonance occurs, the loads increase by several times and the pipes even fall off the fasteners. Begin to "play" and "dance."

With fast filling with liquids, in pipes, due to air blockages, also increases in pressure are generated, which are discharged by hydraulic shocks. This is where the recommendation comes from to drain and fill the heating slowly, by opening a tap a quarter or half. Resonance phenomena, depending on size, weight, fixings, sediment thickness and other factors, change. This imposes additional restrictions. We must not hurry and be attentive.

That is why the design of heat networks of enterprises and apartment buildings is made by specialists taking into account many factors. Heating of individual houses is done according to standard designs.

What kind of coolant is better to fill the heating system
Water has many virtues. But that it freezes and thaws the pipes, at low temperatures, limits its use

Technical progress and cheaper equipment of a smart home allows you to control and change heating parameters remotely using a smartphone. The main thing is to be in the area of ​​cellular communication and the Internet. This further expands the possibilities of using water, because it is possible to take timely measures and prevent its defrosting.

Control of the heating system at a distance
Equipping the heating system with devices for remote control, you can control its operation by GSM at a distance

The rest of the amenities, such as raising the temperature in the room before arrival and economy mode during departure, are included.

The choice of water for heating, it is advisable if a backup heating system is provided. If heating in winter is used periodically or there is a possibility of equipment shutting down and defrosting, then it is better to use non-freezing liquids. For example, in a country house with short visits characteristic of summer cottage life.

Refill non-freezing coolant

Before figuring out how to fill different heating systems with non-freezing liquids or antifreeze, one should understand their varieties.

For normal operation of heating systems, antifreezes (anti - against, freeze - freeze) must be:

  1. non-toxic, eliminating the possibility of the slightest threat to humans;
  2. non-flammable, and their vapors are explosion proof;
  3. inert to the materials from which the heating system is made;
  4. have a heat capacity of at least its calculated value;
  5. differ fluidity.

In its “pure” form, antifreezes are aggressive, capable of destroying pipelines, boilers and heating devices. To reduce or even eliminate the negative properties of non-freezing liquids, they are diluted with water in the proportions indicated by the manufacturer of the formulations.

How antifreeze fill autonomous heating system
Antifreezes are available in two versions, distinguished by freezing temperatures. This concentrated product is -65 ° C and diluted - 30 ° C

Use and additives: anti-corrosion, stabilizing, cleaning, anti-foam and others. The less water, the lower the freezing point and the higher the cost. When diluting antifreeze, it is usually necessary to add the additives that are included. Additives work at a certain concentration.

Without a complex of additives, the compositions can not be used, since they provide the specified parameters.For the same reason, it is not recommended to mix different heat carriers, especially with different bases. Their service life is sharply reduced.
Antifreezes have increased viscosity, they can not be used in heating with natural circulation.

The average shelf life of organic coolants is 3–5 years, through which the additives lose their properties and the liquid becomes aggressive. When replacing the old antifreeze must be pumped out and taken away for recycling, which further increases the cost.

Once cars used water for cooling, but now it is rare. Now in the world, more than 70 percent of heating systems operate on water, but the percentage is constantly decreasing. The reason for inhibiting the widespread use of antifreeze is both their high cost and the increased requirements for equipment, toxicity and the need for their disposal. The antifreezes which have fulfilled the term, for fuller removal merges in the state which is warmed up to 45 degrees.

Now the main equipment is designed for water and manufacturers who value the reputation, often indicate that they do not guarantee work on antifreezes.Or indicate the type of antifreeze allowed under certain conditions. Experimenting yourself is dangerous.

Non-freezing compounds are critical to overheating. They begin the collapse and the formation of gases, solid deposits. Air plugs, burns in boilers and equipment failure are formed. At temperatures of 80 degrees and above, vaporization begins, so modern boilers have heating up to 75 degrees, supported by automation. If exceeded, an emergency shutdown of the boiler occurs. With organic heat carriers, the temperature is reduced to 70 degrees.

As a coolant pour into the heating circuit with natural movement
In gravitational heating systems it is undesirable to use antifreeze. They have too high viscosity for spontaneous movement through pipes. From the open expansion tank, the liquid will evaporate freely, forcing you to regularly fill up the volume and emit caustic volatile substances

For the safe operation of the heating circuit with antifreeze, automatic equipment is required, turning off the heating unit when the temperature is exceeded. If the scheme of the heating system does not have such a device, antifreeze as a coolant should not be used.

Typically, the technical documentation for boilers and equipment indicates the type of coolant. The use of another coolant removes the responsibility from the manufacturer and terminates its warranty service.

For filling systems, heating systems produce heat carriers based on ethylene glycol, propylene glycol and glycerin.

The cheapest ethylene glycol

The disadvantage is toxicity, the dose of 100 - 250 grams is fatal to humans. It has a third hazard class according to GOST. The fumes are also toxic. Permissible limit of maximum permissible concentration - 5 milligrams / cu. meter. Therefore, in open heating systems can not be used. It is also forbidden for double-circuit boilers, because leakage of funds into the main hot water supply is possible.

To eliminate this, the craftsmen make the water supply pressure higher than the heating. But this does not give a full guarantee and can cause, in the event of damage, the failure of the boiler. Use of ethylene glycol is permitted only for closed heating systems.

How does antifreeze fill the heating system
Fill the heating circuit with ethylene glycol-based non-freeze liquids with gloves and a respirator. The liquid is toxic and may cause burns if it comes into contact with the skin.

Heating leaks and breakthroughs are highly likely. If the system is filled with an inexpensive but toxic ethylene glycol based remedy, leakage can create a health hazard for home owners. Relatively low cost is the cause of the application. Health does not buy as antifreeze. Therefore, the choice is yours.

Ethylene glycol has 1.5–3 times greater penetration and aggressiveness to compaction.

In which heating systems can antifreeze be used?
The increased fluidity of antifreeze requires the use of paronitic or teflon seals and special sealing pastes and seals in detachable joints. Standard options for water circuits are not suitable.

Automobile antifreezes, antifreezes, cannot be used categorically, as containing more toxic additives.

In glycol coolants:

  1. the maximum temperature should be no more than 70 degrees, which further increases the size of the batteries;
  2. viscosity is 40–60% higher and pumping requires 1.5–2 times greater motor power and minimization of bends, taps and increased pipe size;
  3. volumetric expansion during heating is 140–150% more, it is required by the same amount, an increased volume of the expansion tank;
  4. density is 15 - 20% higher, strength characteristics increase.

The construction of a new system designed for the use of synthetic heat transfer fluids, respectively, costs 1.3–1.5 times more expensive than the construction of a water analog. We also should not forget about the considerable cost of the most non-freezing liquid.

Alteration of water is also not used, as the service life is reduced and as a result, it costs more. Also, glycol mixtures are aggressive to zinc, appealing flaking and sludge, completely clogging the pipe. In old constructions galvanized pipes are common.

However, taking into account the above deficiencies, ethylene glycol is still used. It is necessary to fill the systems only after all the equipment of the heating system has been adapted to fill the antifreeze.

A special feature is the need to arrange equipment for refueling, on impermeable coatings, to prevent the ingress of glycol into the living quarters and to carefully control the connections of the transition hoses. Although this, neat masters, make when refueling any antifreeze.

The specificity of the use of propylene glycol

Recently, it actively displaces other types of coolants, although in terms of its physical and technical parameters it does not differ much from ethylene glycol and requires almost the same change in the equipment of heating systems.
Belongs according to GOST to the second class of danger and also requires disposal. Couples of maximum concentration limit - 7 milligrams / cubic meter.

Non-freezing antifreeze coolant for filling heating systems
Antifreezes of this group are produced on the basis of pharmacological propylene glycol, which does not have such a harmful effect on organisms as the previous version

The advantages of this non-freezing coolant:

  1. relatively environmentally friendly and harmless to people. This is the main reason why now many manufacturers recommend it for single-circuit and double-circuit boilers;
  2. possesses the greasing properties that facilitates work of pumps;
  3. at full evaporation of water does not freeze, keeping fluidity;
  4. corrosivity is very low, and with additives it is still improving;
  5. in case of spillage, rinse with water and wipe.

There is a flaw on polypropylene glycol. it
its value, which is 1.5 - 2 times higher than ethylene glycol, is produced mainly abroad. Fluid is aggressive
to metal pipes, incompatible with pipelines constructed from galvanized pipes, since upon contact with zinc, the additive composition loses its properties. At temperatures above the permissible decomposition begins with the formation of gases, foam and solid insoluble precipitate.
Despite all these shortcomings, it is considered one of the best heat carriers.

Feature of glycerol coolants

The same harmless as propylene glycol, at permissible temperatures. They historically before all began to use for these purposes, getting glycerin from fat. Strait is not dangerous. The advantage is the price, which is lower than that of propylene, while remaining above ethylene glycol. Therefore, it is used by falsifiers to dilute polypropylene glycol.

How antifreeze correctly fill the heating system
Non-freezing liquid based on glycerin belongs to the elite category. It is safe for the environment and the environment. Filling such antifreeze can be carried out as well as filling the system with water.

Even some European manufacturers add it to about 10%, so you need to be careful and read the composition. On the other hand, in the European Union, as the main component of the coolant, glycerin is not used.

Glycerin has wider up to 105 degrees, extreme temperatures.Danger class two.


  1. if the maximum temperatures are exceeded during decomposition, a poisonous gas with an unpleasant odor is released;
  2. when evaporating, becomes gel-like, burns and decomposition begin, you need to regularly compensate for evaporation by adding distillate;
  3. have increased viscosity and require larger diameter pipes;
  4. it is easily foamed, which is partially removed by additives;
  5. has a high penetrating power and requires the use of paronit and teflon proklatok.

It has significant corrosivity, and has long been rejected by automakers. Due to modern additives, it is reduced and reduced to nothing. Yes, even with proper operation.

Glycerin coolants, however, are recommended to a greater degree than ethylene glycol for their harmlessness and with a complex of additives work satisfactorily in heat networks. The trouble is that in pursuit of money, produce products without a full range of additives or without them. Need to be careful when buying.

In a special form can be attributed to the heating system with electrode boilers, in which the coolant is also a heating element. Heating occurs when current flows through the solution during its ionization.

The solution, in addition to the above, should have a calculated electrical resistivity of the order of 3.5 - 4 KOhm · cm. To do this, use an aqueous solution or solution of propylene glycol with additives, which create the necessary electrical characteristics.

What antifreeze is better to fill the heating system
This option is more expensive, more difficult to find on sale, canisters are not always labeled. Manufacturers with an impeccable reputation for marking indicate "elite"

Conclusions and useful video on the topic

The video will vividly present the process of filling the heating circuit and setting the expansion tank:

Common to all coolants is the gradual start-up of the system. The temperature must be increased slowly, in steps, not only because of the coolant, but also of additives, which also change their properties with temperature. The process of filling systems with water and antifreeze is similar, but the requirements for quality of work and safety when refilling antifreeze are increasing. The antifreezes which have fulfilled the term, demand a disposable container and export for utilization.

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