Antifreeze for the heating system of a country house

The principle of operation of antifreeze

Water at 0°C abruptly and abruptly turns into ice, expanding by 11%. The pipes cannot withstand such a load. The heating system has to be dismantled, including the boiler and all radiators. Water is a good solvent, so even a small amount of antifreeze greatly shifts the crystallization point of water, and abrupt transformation into ice does not occur.

At subzero temperatures, water with the addition of antifreeze slowly thickens, and the liquid expands slightly, so the heating system remains safe and sound.

For example, the crystallization of water with 30% antifreeze liquid (propylene glycol) is so slow that there is no need to dilute the coolant to -30°C; it is enough to add antifreeze to the design temperature of -12-15°C. As the temperature drops below the calculated value, such a mixture will slowly but surely harden, and only at -30°C can it freeze completely.

Should I dilute with water or not?

The origin of this issue is due to the fact that equipment manufacturers set the same requirements, worrying about the safest and most efficient operation possible. Buyers stick to their line, driven by the need to save money. And coolant manufacturers maneuver between the requirements of manufacturers, buyers and sales practices. As always, the truth is somewhere in the middle.

Manufacturers of antifreeze liquids mainly offer “-65C” or “-30C” coolants to the market. Firstly, this is due to established demand, and secondly, such a coolant is guaranteed not to be frozen at the time of sale.

Equipment manufacturers have their own truth. Thus, the density of non-freezing liquid marked “-25C”, mainly recommended by equipment manufacturers for reasons of optimal fluidity, is 1.03 g/cm3, and that of liquid “-30C” is 1.04 g/cm3.

The fact that the content of the main substance in the coolant will be several percent higher is not an “exorbitant” deviation, but taking into account the fact that water can be “added” to the coolant either when recharging the circuit, or if water is not completely drained from the system after flushing , a “reserve” of concentration is simply necessary.

On the other hand, diluting the coolant from “-30C” to “-25C” - and this value is 3-4% - will not bring tangible savings to the buyer, but will increase the risk of losing other necessary properties. But in the case when the buyer plans to use concentrated coolant “-65C” and dilute it, the savings can already be up to 20%.

What is the difference between green and red antifreeze?

Pure 100% antifreeze is not used as a coolant - it is always diluted: from 20 to 35% antifreeze and 80-65% water, respectively. Only 2 types of antifreeze based on dihydric alcohols are used in heating: ethylene glycol and propylene glycol. Manufacturers produce both a concentrated composition and an already diluted one for pouring into the heating system. Ethylene glycol is a concentrated red solution, and ethylene glycol is a green solution. I will describe their differences below.

Features of using water as a coolant

From the point of view of heat transfer efficiency, water is an ideal coolant. It has a very high heat capacity and fluidity, which allows it to deliver heat to the radiators in the required volume. What kind of water should I fill? If the system is closed, you can fill it with water directly from the tap.

Yes, tap water is not ideal in composition; it contains salts and a certain amount of mechanical impurities. And yes, they will settle on the elements of the heating system. But this will happen once: in a closed system, the coolant circulates for years, and replenishment with a small amount is very rarely required. Therefore, some amount of sediment will not cause any tangible harm.

Water as a coolant for heating systems is almost ideal

If the heating is of an open type, the requirements for the quality of water as a coolant are much higher. Here, gradual evaporation of water occurs, which is periodically replenished by adding water. Thus, it turns out that the concentration of salts in the liquid increases all the time. This means that sediment also accumulates on the elements. That is why purified or distilled water is poured into open-type heating systems (with an open expansion tank in the attic).

In this case, it is better to use distillate, but getting it in the required volume can be problematic and expensive. Then you can fill in purified water that has been passed through filters. The most critical is the presence of large amounts of iron and hardness salts. Mechanical impurities are also useless, but they are the easiest thing to deal with - several mesh filters with cells of different sizes will help catch most of them.

The main features of any type of non-freezing liquids are:

crystallization of salts and their precipitation on the walls of pipes and batteries (radiators) when the coolant reaches the critical boiling point;
a noticeable decrease in the efficiency of the system in this case.

Such situations can be avoided by uninterrupted operation of the boiler heating system and temperature control. It is advisable to reduce the corrosive properties of antifreeze by adding special inhibitors to them yourself.

Ethylene glycol in the heating system

Raspberry colored solution. A toxic substance used in the automotive industry, the production of motor oils, plastic and cellophane. It has an extremely low pour point of -70°C. It is used primarily in heating and anti-icing systems of industrial facilities and football fields. It is not recommended to use ethylene glycol in heating systems of country houses due to its toxicity.

Antifreeze selection factors

Low cost - filling the heating system will require several hundred liters, and during operation it may be necessary to top up or completely replace it.
No toxic effect on the environment - pipes can leak, even slightly, and the coolant will poison the residents.
No aggressive effect on heating system materials.
The maximum possible heat capacity, which will allow you to reduce the amount of fuel to maintain a stable temperature.

The best choice would be to buy a propylene glycol-based antifreeze. Ethylene glycol is a toxic substance. The remaining bases are characterized by aggression on the components of heating systems. Your needs come first. The heating must work properly and without breakdowns. Maintenance should not be expensive or inconvenient.

Propylene glycol in the heating system

Green solution, food additive E1520, used in the cosmetics industry. Pour point -50°C. 3 times more viscous and 2 times more expensive than ethylene glycol. It is used in buildings where there is a risk of the system defrosting, but compliance with environmental characteristics is required. We use propylene glycol in recuperators of restaurant ventilation systems. In our country, propylene glycol for the heating system is produced from imported raw materials, and therefore is much more expensive than ethylene glycol.

Rating of the best coolants on the domestic market

WARM ECO HOUSE

Propylene glycol substance. The manufacturer recommends using it in dual-circuit heating systems. During operation, it significantly loses its anti-corrosion properties. Not suitable for electrolytic boilers.

ADVANTAGES:

Fire and explosion proof
Provides reliable protection of heating and air conditioning systems from defrosting, scale and corrosion
Additives based on mineral salts do not contain harmful nitrites, amines and phosphates
Do not have an aggressive effect on metals, plastic, metal-plastic, rubber, paranit and flax

FLAWS

Not detected

WARM ECO HOUSE

DIXIS-65

They are used both in industrial systems and for heating small private houses. Feature - freezing temperature - 65 degrees. When used in a region with mild winters, the substance can be diluted with water, which will reduce its cost. It has gentle properties on heating system materials and extremely low flammability.

ADVANTAGES:

High frost resistance
Heat exchange devices are not destroyed when frozen
Maintains the heating system in ideal condition in the temperature range -65°C ... +95°C
Can be used by diluting with regular tap water
Prevents scale formation

FLAWS

Not detected

DIXIS-65

Warme ECO 30

Harmless glycerin antifreeze, which has a neutral effect on humans and the environment. Diluted with a complex of additives to reduce the aggressive effect on the components of the heating system. Thanks to this, the metal and sealing elements do not damage. Contains a phosphor dye.

ADVANTAGES:

Environmentally friendly product
Incombustible
Non-toxic
Explosion-proof
Contains a special complex of anti-corrosion additives

FLAWS

Not detected

Warme ECO 30

TermoTactic EcoGreen – 30°

It has a glycerin base with added additives. Produced on the basis of European production. It is environmentally friendly and therefore recommended for residential buildings.

ADVANTAGES:

Highly hygroscopic
Easily mixes with distilled water in any proportions
Non-toxic, ensures the safety of the environment and human life during operation and disposal
The presence of a functional additive “corrosion inhibitor” - prevents the occurrence of physiological and physico-chemical processes when interacting with metals, plastics, rubber and paranitic seals
Retains unchanged its original state when heated and cooled

FLAWS

Not detected

TermoTactic EcoGreen – 30°

PRIMOCLIMA ANTIFROST – 30

Does not swell when frozen. There are no toxic components in the composition. Can be used for up to 8 years without replacement. The additives in its composition allow you to extend the life of heating system components.

ADVANTAGES:

Effective package of anti-corrosion additives
Inertness to sealing and gasket materials
Long service life - up to 8 heating seasons
Cost-effective - with a system volume of 100 liters, 115 kg of coolant will be required, and the product is completely ready for use
Compatible with most antifreezes on a similar basis

FLAWS

Not detected

PRIMOCLIMA ANTIFROST – 30

Aquatrust – 30

Propylene glycol antifreeze with extended service life. It is characterized by high cost. Used in enterprises, including public catering. Has antibacterial components.

ADVANTAGES:

Latest anti-corrosion formula
Extended life of corrosion inhibitors and antibacterial additives
Improved heat transfer properties
Service life is 3 times longer than traditional coolants

FLAWS

Not detected

Aquatrust – 30

Which coolant should I choose for heating?

For a heating system, the differences between ethylene glycol and propylene glycol are insignificant, but different freezing temperatures (-70 and -50 ° C) affect the percentage of the substance. To ensure the same crystallization temperature (-25°C), almost 2 times less ethylene glycol is required than propylene glycol, but the relationship is not linear.

For example, when the concentration of ethylene glycol in water becomes more than 50%, its characteristics begin to decline. This is due to the ineffective operation of anti-corrosion additives, which do not come into contact with water well.

Characteristics of non-freezing liquids for heating

How low-freezing liquid for heating systems behaves in the circuit is primarily influenced by the quality of the additive package and, of course, operating conditions. Regardless of what main active element is added to the glycol base, all compositions have anti-corrosion and anti-foaming properties.

Without these additives, heating fluid is very aggressive. All antifreezes foam, but glycerin antifreeze liquids for home heating systems especially. Foam is an air-containing substance, and air leads to disruption of circulation, the formation of air pockets, as well as water hammer in the heating system.

The additive package has its own temporary resource. After a certain time, additives break down at the molecular level.

In this case, a precipitate forms and acid is released. It turns out that nothing can smooth out the aggressiveness of the coolant for heating the house, and moreover, everything is aggravated by the release of acid. Service life of antifreeze liquid:

based on ethylene glycol – five years;
based on propylene glycol – five years;
glycerin-based - up to ten years.

This is the service life of the composition under favorable operating conditions. The main requirement is, of course, temperature. When the coolant temperature rises to 90 degrees, the non-freezing liquid begins to disintegrate and loses its properties. This only happens if the boiler is not started correctly after a long period of inactivity, or if there are errors during installation.

Direct contact of the heat exchanger with the flame is undesirable if antifreeze is poured into the circuit

For example, when a heat exchanger is built into a conventional oven. Some install it so that it comes into contact with an open flame. If you plan to use antifreeze for stove heating, then you cannot do this. It is necessary that there is a layer of brick between the heat exchanger and the flame. It will protect the coolant from too hot flames and distribute the heat evenly. In this case, the non-freezing liquid for stove heating will not overheat.

Characteristics that are affected by the quality of the additive package:

thermal conductivity;
density;
viscosity;
fluidity;
thermal expansion.

The better the additives, the higher the performance will be. That is, as close as possible to the characteristics of water. In the case of the coefficient of thermal expansion, it should be as small as possible.

Considering the fact that the volumetric expansion of the antifreeze is greater than that of water, it is necessary to provide an expansion chamber with a 40% larger volume.

The thermal conductivity of antifreeze is lower than that of water. Glycerin antifreeze liquids have the lowest thermal conductivity. In relation to water, it is only 85%; for other anti-freeze products the figure can reach 90%. As you can see, the difference is not that big.

Antifreeze liquids are half as dense and viscous as water. These qualities make circulation difficult. To pump the coolant through the circuit, you will need a pump of greater power, and it would also be a good idea to assemble a heating circuit from pipes with a cross-section that is one step larger. For example, if we are talking about polypropylene pipes. then instead of 25 diameter, it is better to take 32.

Despite the fact that antifreeze liquid is denser and more viscous, it has a lower surface tension coefficient, that is, it is more fluid. Do you know that you can fill a glass with heaps of water? The slide, of course, will be small, but even visually it can be seen that the liquid rises above the edge of the vessel. This won't work with anti-freeze. Due to such high fluidity, it flows out where water does not penetrate due to surface tension. In other words, if there are microcracks and even very small holes, then the non-freezing liquid will find its way out there.

Therefore, often, after there was water in the circuit and they decided to pour anti-freeze into it, leaks appear. Main leak points:

pipe joints;
connections between radiator sections;
connection points for additional elements;
in the boiler itself.

Water has another useful property, thanks to which a minor leak can disappear by itself. Metal particles settle on the edges of cracks and seal them. Of course, this is just scale, which, if the system is flushed and further pressure tested, will be removed and the flow will resume.

Which antifreeze is best for heating a home?

The main criterion for choosing antifreeze is safety!

Propylene glycol is used in the food industry. The substance is not toxic. It is used as antifreeze in heating systems of cottages, country houses and premises with constant occupancy.

If the building does not require environmental safety, for example, warehouses, garages and production workshops, you can safely use ethylene glycol. In all other cases - propylene glycol.

When there was water in the system, everything was fine, they filled in the coolant and all the connections started leaking.

Arnau

It's time to decide what to fill the heating system in a country house with: distilled water or antifreeze.

The main argument against antifreeze is that it corrodes connections, leaks are possible and components need to be changed frequently.

Indeed, non-freezing liquids are more fluid than water. And fluidity increases with increasing temperature. They do not contain chemical compounds that, by forming calcium deposits, can clog microgaps. Even if the microgaps become clogged with something, coolant additives will “clean” the clogged formations and restore the leak. Therefore, more attention must be paid to the assembly of joints in a system where it is planned to use antifreeze. And, as mentioned earlier, before starting it is necessary to carry out commissioning work, including pressure testing of the system.

Glycerin in the heating system

I received a lot of questions about “glycerin”. Glycerin-based coolant in the heating system is unacceptable even in a diluted state.

Firstly, monstrous kinematic viscosity at negative temperatures (at 0°C -9000 m2/s x 106 - glycerin, 67 m2/s x 106 - ethylene glycol) - and therefore monstrous pressure losses. It will be difficult to push glycerin-based coolant through the pipes.

Secondly, the adhesion of organic glycerin particles to the surface of the boiler heat exchanger, its overheating and complete failure. Diluting glycerin with alcohols only leads to the formation of explosive compounds.

Any other non-freezing liquids, for example, antifreeze in the heating system, are unacceptable, because do not contain the required amount of anti-corrosion additives. The cost of antifreeze for heating is determined by the quality of these same additives, thanks to which some antifreezes last 5 years and others 10. Over the years, the antifreeze in the heating system oxidizes to form acetic acid, which leads to the destruction of brass connections on radiators, so it is important to change the coolant on time.

What is the service life, how do you know: when to replace?

The question is quite common.

Andreic

Experts, clarify the situation: today contractors said that antifreeze has a validity period of 5-7 years. Then it loses its properties, begins to precipitate, and generally does not flow through the heating system as it should. True or not?

For coolants that contain organic (carboxylate) additives, the service life is 10 seasons (10 years), for coolants with “ordinary” silicate additives, this period is about 5 years (heating seasons). In order to control quality, every year, after the end of the heating season, you can carry out a simple procedure - pour a small amount of coolant into a transparent glass container. The resulting sample is visually inspected for the presence of mechanical and other impurities, color, and transparency. If the coolant contains mechanical impurities (crumbs, grains of scale), it can be drained, filtered, flushed the system and refilled. If there are traces of chemical changes (flakes, clots), you need to contact a specialist.

Heating with antifreeze or water

After reading this section, you will most likely refuse antifreeze in your heating system. The main advantage of antifreeze - the safety of the system at subzero temperatures - is completely negated by its disadvantages.

Low heat capacity of antifreeze. Increasing the size of radiators by 20-23%
The heat capacity of antifreeze is significantly lower than the heat capacity of water. By diluting water with 35% antifreeze, we lose approximately 200 W per 1 kW of thermal energy. This means that the size of pipes, radiators and boiler must be increased by 20%. In terms of a country house of 300 m2, we lose approximately 60 thousand rubles by increasing the size of the system. Antifreeze is not applicable at all for underfloor heating systems, again due to low heat capacity.

The service life of antifreeze is from 5 to 10 years. Over the years, antifreeze oxidizes and successfully destroys brass connections. After 5 - 10 years, ethylene glycol and propylene glycol must be drained, disposed of and replaced with a new one. You will not only have to buy new antifreeze, but also pay to dispose of the old one. Unfortunately, in our country there is no service for recycling ethylene glycol in small volumes, so finding someone to hand over this chemical to will be difficult. I won’t consider the idea of dumping antifreeze on my neighbor’s property.
The use of sectional radiators in systems with antifreeze is unacceptable. Rubber sectional gaskets quickly oxidize, and the radiators leak. We use only steel panels. The use of galvanized pipes is also unacceptable. Antifreeze safely washes away the zinc, and the pipe remains bare.
Why is antifreeze useless for a country house? Antifreeze will successfully cope with the task - the heating system will not freeze in winter in your absence, but what to do with the water supply system? At subzero temperatures, water supply pipes will freeze faster and with worse consequences, because... laid not only in the floor, but also in the walls. You will have to remove the tiles, beat the screed and change the pipes in the bathrooms, showers, kitchen, and also replace the entire water supply system of the boiler room. Of course, pumping antifreeze into the water supply system will not work, nor will laying all the pipes with a heating cable.

Conclusion: Antifreezes are suitable either for heating small country houses for temporary residence, or large warehouses, workshops and enterprises. In the heating system of a full-fledged country house, antifreeze is useless.

Which radiator to choose

For a private home, metal radiators are chosen. The most popular types of metal for radiators are cast iron (in many old apartments), steel, bimetal, and aluminum.

Cast iron batteries consist of sections, they are very strong and durable. But the appearance and design are outdated, and they are very heavy to move and mount.

Steel radiators are more beautiful and lighter. They can be either panel or tubular. The downside is its fragility and greater susceptibility to corrosion. Aluminum batteries are light, beautiful, and convenient for the garden. But they are very selective in the composition of the liquid that is heated in them

It is necessary to approach the choice of antifreeze with special attention. Bimetallic radiators are made of an alloy of aluminum and steel and are the most successful solution in your home. Only the price is high compared to aluminum radiators.

Which liquid to choose for heating installations

Water is the standard and most common liquid used in heating. It is an environmentally friendly and non-toxic substance, inexpensive. At the same time, with prolonged use it provokes scale and corrosion processes.

If frost suddenly sets in and the heating is not started, pipe ruptures are possible (since during the transition from liquid to solid state, the volume of water increases by approximately 9%).

Thus, despite all the disadvantages of using ordinary water, if you still live in the house permanently, then it is better to use it in the heating system.

Antifreeze is mainly used in cases where the room is rarely visited in winter and the heating does not work constantly, but is started as needed.

Determining the required amount of antifreeze

The volume of non-freezing liquid that is supposed to be poured into the heating system is calculated based on:

What heating design is used;
What material is it made of?
Its internal volume;
The area of the heated room.

Some equipment parameters can be determined visually; more detailed nuances can be found in the operating instructions. If exact numbers are not found in the technical documentation (for example, the use of antifreeze is not recommended by the manufacturer), then more complex calculations and, possibly, a professional approach will be required.

In this case, for calculation you can:

Use specialized literature;
Calculate the volume depending on the number of batteries and sections in them. When taking into account the volume of liquid filling one section;
To take the most rational route is to contact specialists. who will carry out all the necessary calculations in the shortest possible time and with a professional approach.

Pouring liquid into the heating system

What is the optimal coolant liquid?

The ideal coolant fluid for autonomous heating systems must meet the following requirements:

Have sufficient heat capacity to effectively accumulate and transfer thermal energy.
Be chemically neutral in composition so as not to provoke the occurrence of corrosion in the elements of heating equipment and not to corrode sealing gaskets at circuit connections.
Maintain operating condition over a wide temperature range.
Do not contain compounds and substances that settle in pipes and batteries, causing them to become overgrown with solid deposits.
Be stable in composition - do not decompose or split into various chemical components under the influence of high temperature or over time. Its density, viscosity, heat capacity and chemical inertness must remain constant.
To be safe for the inhabitants of the house heated with its help, that is, to be non-toxic and non-flammable.
Have an affordable price.

The set of requirements is defined: it is logical and understandable. Unfortunately, a coolant liquid that meets all these criteria does not exist in nature.

Coolant AQUA TRUST -30C propylene glycol 20kg

Different liquids used for heating have an incomplete set of the above properties and characteristics, and the enhancement of some can often be achieved at the expense of the deterioration of others. Because of this, the problem of acquiring coolant fluid is considered a difficult task. A competent choice of the optimal coolant for specific objects necessarily takes into account both the nuances of the system design and the features of the upcoming operation mode. At the same time, they start from the priority parameter for the object, which becomes the decisive factor.

Let's look at the problem of choice using specific examples. If a heating system with a solid fuel boiler in a private house where the owners live permanently, without leaving it for a day, requires coolant, it is advisable to choose water. The same introductory notes, but the boiler is electric, and power outages are common? It is worth thinking about changing the coolant or thermal energy generator, since in severe frost even a few hours of inactivity of the electric boiler can cause system failure due to water freezing. If the home is used occasionally on weekends or holidays, then it is better to fill the heating system with a non-freezing liquid substance, but this requires additional equipment and changes to the design of the system, as well as reliable sealing of all its elements.

You also need to understand that coolants have not yet been invented that can be used forever. Over time, any filler in the heating system needs to be replaced. Therefore, the cost of the coolant is one of the decisive arguments for choice. Sometimes boiler manufacturers solve the problem of choice by indicating in the instructions the type, and sometimes even the brand, of the recommended composition. Deviation from such recommendations leads to termination of the warranty period, which must also be taken into account.