Filling and selection of antifreeze in the heating system

Antifreeze is called non-freezing, emphasizing the main property - maintaining fluidity at low subzero temperatures. Motorists use anti-freeze in the cooling system. Another area of ​​its application is heating systems for country houses. Antifreeze for the heating system allows you to prevent freezing, which occurs during a long-term power outage or a prolonged departure from a country house in winter.

Types and features of antifreeze

Antifreezes are classified according to the type of base:

• propylene glycol;
• ethylene glycol;
• solutions based on alcohol and glycerin.

The varieties differ in physical and technical characteristics. When choosing one of them, you should take into account the features of the heating system and the conditions in which it operates. To fill the systems, special formulations are produced. Automotive antifreezes, such as antifreeze, are not suitable for heating. They contain a lot of toxic substances and have a negative effect on rubber and metal elements of the line, they serve 1, maximum 2 years.

Propylene glycol

The main positive property of the propylene glycol composition is harmlessness. It is non-toxic, can be used in open heating systems and double-circuit boilers, where water is heated for water supply. Even if propylene glycol spills into the water, there will be no significant harm to health.

The technical properties of propylene glycol antifreezes are also good. They do not have an aggressive effect on the inner surface of the system elements.

There are also disadvantages:

• high viscosity, which is twice the value of the viscosity of ethylene glycol;
• interaction with zinc: a reaction occurs with the formation of white insoluble flakes, the metal is destroyed;
• high price.

It is easy to distinguish propylene glycol coolant from ethylene glycol coolant: the former is colored green and often has ECO markings. Instead of propylene glycol antifreeze, you can buy counterfeit glycerin.

Ethylene glycol

Ethylene glycol formulations are highly toxic. This is their main drawback. The danger of ethylene glycol is indicated by a red or yellow color of the liquid. Thanks to its bright color, it is easier to detect a coolant leak. It may harm the lungs or skin. The lethal concentration when ingested is 2 mg per 1 kg of body weight. In this regard, the disposal of this type of antifreeze is a certain problem. For safety reasons, ethylene glycol coolant is used only in single-circuit systems, where there is no risk of entering the water supply circuit. The technical properties of ethylene glycol allow the use of fluids based on it at temperatures down to –65 ° C.

In some countries, ethylene glycol heat transfer fluid is prohibited.

Alcohol and glycerin based solutions

There is an ambiguous opinion about glycerin coolants.Some say that glycerin is the best household antifreeze for a heating system, others point to many of its disadvantages:

• high viscosity of the substance, due to which the wear of equipment is accelerated - to compensate for the high viscosity of glycerin, the composition is diluted with alcohol;
• higher density compared to other antifreezes;
• transformation into poison at temperatures above 90 ° C;
• the risk of foaming;
• relatively low heat capacity;
• chemical interaction with rubber and plastic;
• after evaporation of the water, it becomes hard or jelly-like.

However, glycerin coolants have many positive properties:

• fire and explosion safety;
• environmental friendliness;
• chemical inertness to zinc;
• wide range of operating temperatures: from –30 ° C to 105 ° C;
• low cost;
• long service life - 10 years;
• do not expand when frozen.

Glycerin formulations are produced according to TU, and this is another drawback, because manufacturers themselves set the standards.

The production of glycerine antifreezes is not carried out in some countries.

You can also use solutions with a content of 40-55% ethyl alcohol as a heat carrier. They are environmentally friendly, crystallizing at –30 ° C. However, their use is limited to hermetically sealed closed systems because of their increased volatility. The boiling point is 90 ° C, which is the lowest among all types of heat transfer fluids.

Advantages and disadvantages

Distilled water is also poured in as a coolant, but if in winter it is possible for the owners to be absent from the house for a long time or the electricity is periodically cut off, the coolant in the radiators may freeze. In such cases, it is recommended to fill the system with heating antifreeze.

Benefits:

• pipes will not burst due to the expansion of frozen water;
• no need to drain water from the system during your absence;
• antifreeze has a low freezing point - down to -65 ° C, and even at a lower temperature it does not turn into ice, but becomes jelly-like, expanding to a much lesser extent than water;
• when the temperature rises, the frozen coolant retains its properties;
• the composition contains additives that prevent the formation of scale and reaction with metals.

Disadvantages:

• low-quality antifreezes destroy the elements of the heating system, as a solid precipitate falls out in them, which destroys fittings and devices;
• a reduced level of heat capacity in comparison with water (less by 15%), in order to compensate for this drawback, it is necessary to increase the circulation rate of the coolant by exactly the same amount;
• increased viscosity (30-50% higher than water) and higher density (5-10%), which is why it is necessary to install more powerful pumping equipment;
• toxicity;
• sedimentation over time;
• high price;
• the need for thorough sealing of joints, due to increased fluidity (50% higher than that of water).

Despite the disadvantages, antifreeze is used in heating systems, since it practically does not freeze and does not expand, leading to damage to pipes and equipment.

Features of the use of antifreeze in the heating system

Because glycol formulations are unsafe, precautions are taken when using them. In addition, there are certain features of the use of antifreeze in the heating system:

• The glycol coolant should not be poured into an open system where the liquid in the expansion tank is in contact with the atmosphere, because toxic substances can enter the air. This is allowed only when using propylene glycol coolant, if there is confidence in its quality.
• When purchasing a coolant from another manufacturer, in order to add it to the system, you need to check for compatibility with the old antifreeze, because the additives can neutralize each other, which leads to the disappearance of anti-corrosion properties. If it is not known which coolant was used before, it is necessary to completely drain the liquid.
• To work in a system with antifreeze, a pump is required 60% more powerful than for water.
• Radiators must be selected with a higher degree of heat transfer, for example, aluminum or bimetallic. In addition, it is advisable to choose a model with a large inner diameter and volume.
• The system does not work with automatic air vents, so Mayevsky's taps are installed.
• The system must be equipped with an accurate temperature controller, since exceeding certain limits leads to the decomposition of the coolant. The reaction is accompanied by precipitation, which subsequently becomes the cause of the formation of carbon deposits, corrosion, acid, foam and airing of the system.

Only with proper operation and compliance with all recommendations for the selection of equipment, the use of antifreeze in the heating system will be beneficial.

Pouring coolant into the heating system with your own hands

Antifreeze for heating ages over time, its heat capacity and anti-corrosion properties decrease, so it is periodically changed. The average frequency is 5 years. Before filling the coolant, it is necessary to drain the old antifreeze from the system.

Work order:

1. Be sure to heat up the heating boiler, regardless of the ambient temperature.
2. Open the batteries and put the system into gravity mode.
3. Disconnect the boiler and other devices of the system from the mains.
4. Buckets and basins are prepared for draining the old coolant.
5. With the help of a shut-off valve, the pump is disconnected, since without a coolant it instantly fails. The old antifreeze will remain inside, but its volume will be small, so this will not affect the operation of the system.
6. Open the valve and fill the containers. It is preferable to drain the system through a filling valve located close to the boiler, at the lowest point. If a drain hole is not provided, one end of the hose is connected to the battery drain hole or to the Mayevsky tap, the other end is inserted into the container.
7. After draining the coolant, the system is flushed with clean water or solutions specially designed for this purpose.
8. In accordance with the manufacturer's instructions, dilute the liquid according to the required freezing point. The freezing point has a non-linear dependence on the amount of water injected - when diluting 20 liters of antifreeze with a freezing point of –65 ° C with 50% water, the freezing point will be –20 ° C, and not –32.5 ° C, as one might expect.
9. Clean the dirt filter.
10. Using a pump connected to the injection port, the system is filled with fresh composition.
11. In the process of work, it is necessary to release air, controlling the pressure according to the readings of the manometer.

To dilute the coolant, use only distilled water that does not contain calcium and magnesium salts, otherwise a precipitate will form. In extreme cases, you should check the reaction by separately mixing tap water with a small amount of antifreeze in the right proportions. It is imperative to combine the composition with water in a separate container to ensure uniform mixing. Pour antifreeze first and then water into the system. This leads to uneven heating of radiators, failure of pumping equipment, foaming. If, unknowingly, the system was filled in this way, the pump is turned on at minimum power and air is gradually released. Mixing will occur over time, but there is no guarantee that it will be uniform.

If ethylene glycol coolant is added to the system, the containers used in the process must be disposed of and the pump must be rinsed with hot water and detergents.

Heat carrier manufacturers

Antifreezes consist of 30-65% glycol, 30-50% of distilled water, 3-4% of additives that prevent foaming, metal corrosion, and precipitation. There is a wide range of antifreezes on the market designed for the heating system of a country house. They are made primarily from imported raw materials and are sold at roughly the same price. If a product is too cheap, you should question its quality. You can check the composition with soda. Since counterfeit antifreezes are mostly acidic, you can mix a pinch of soda with a small amount of coolant. If at the same time there is a hissing and foam is formed - the product is of poor quality, if the reaction does not occur - the antifreeze is good.

The best antifreezes are as follows:

• Dixis-65. Heat carrier with the best crystallization properties. This antifreeze is suitable for gas and electric heating boilers, systems with elements of cast iron, copper, plastic, aluminum, brass. Ambient temperature from –65 ° C to + 95 ° C. It can be used for heating houses in the Far North. When used in milder climatic conditions, the heat carrier can be diluted 1: 1 with water. Advantages: service life - at least 5 years, fire safety.
• Eco warm house. Propylene glycol coolant with a crystallization temperature of –31 ° C. Service life - 5 years or more. The boiling point is 106 ° C, and destruction occurs only at + 170 ° C. It is compatible with sealants and does not expand.
• Thermagent-65. Domestic antifreeze made from German raw materials. Can be used in systems with rubber gaskets, sealant. Retains properties for up to 10 years and has a low freezing point. Suitable for ambient temperatures down to –65 ° C.

Antifreeze is a heat transfer medium that has a lower coefficient of expansion than water. This property is of primary importance. For the rest of the physical and technical parameters, water is superior to antifreeze. The use of non-freezers must be competent. Then the service life of the system will increase.