Despite the advancement of alternative methods of space heating, in the vast majority of cases, the liquid heating circuit acts as the main source of heat. Due to its economy and efficiency, it is optimal in the conditions typical of our long latitudes for long winters.
The downside is that water can freeze. Therefore, in addition to it, an anti-freeze coolant is also used for heating systems, replacing water. In this article, we will take a closer look at its main varieties, consider their significant advantages and main disadvantages.
We also present an algorithm for calculating the required volume of coolant for a particular system and recommendations for choosing the type of fluid for heating circuits.
List of heat carrier requirements
The main task of the fluid in the pipes is the transfer of thermal energy from the boiler to the radiators.
For the heating system to be safe and energy efficient, the coolant must meet a number of important requirements, including:
- preservation of pipes from corrosion;
- chemical inertness to seals installed in the pipeline;
- a range of operating temperatures suitable for the operating parameters of the pipes (from freezing to boiling);
- high heat capacity to accumulate as much heat as possible;
- minimum ability to form scale;
- complete safety: no toxic fumes and maximum explosion and fire resistance;
- stable chemical composition - the liquid should not decompose and change its physical properties under the influence of high temperatures.
And now the main question: what antifreeze for modern heating systems meets all the requirements?
The answer may disappoint, but today in nature there is no such fluid. Such an ideal chemical composition has not yet been created. Therefore, the question of selecting the best option is a very urgent task for today.
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A heat carrier is a medium that can move within a heating system in order to transfer the heat received during heating in a boiler to a consumer
The most common type of coolant used in the CIS countries is water. Its temperature in heating networks is 60 - 70º. In single-tube gravity systems it can reach 95 - 105º at the outlet of the boiler
The second most popular type of coolant is steam, the heating temperature of which reaches + 130º. Complex and bulky contours are constructed mainly in utility rooms
In air heating circuits, which are not very common in our countries, the heat carrier is air heated to + 60º. In fact, this is a secondary coolant heated by steam, electricity, water
In water heating circuits that have direct communication with the environment, only water can be used as a heat transfer medium.
Due to the existing probability of liquid freezing in the northern regions, non-freezing liquid is used instead of water in the water circuits - antifreeze solution
The antifreeze solution is not applicable if a double-circuit boiler is installed in the house, which supplies heat and water to the hot water supply. Its use is not permissible if the heating and domestic hot water systems are interconnected
Water is the cheapest and most affordable heat transfer option, and therefore the most popular. It is characterized by good fluidity, due to which it spreads heat with a high speed.
What is coolant for?
Water heating system
Steam heating in the utility rooms
Air heating medium
Open water heating circuit
Closed circuit heating system
Prohibition of pouring antifreeze
The benefits of water as a coolant
When is antifreeze necessary?
Before you begin to consider alternative fluids, do not discount water. If heating is installed in a house where residents live constantly, then water will be one of the safest and most reliable options.
It as a coolant has optimal parameters for circulation along the contours of heating systems.
However, at the peak of winter frosts, the slightest crystallization of water can cause a serious accident with the destruction of the pipeline and components of heating equipment.
If we are talking about a country house, which is periodically hit, or when the family often leaves their monastery on weekends, leaving the heating unattended, then the heat carrier used must be resistant to the typical low temperature range for the region.
Only for the use of chemical compounds as a carrier of thermal energy, it is necessary to prepare heating circuits. The system must be completely sealed, as the liquid is toxic and flammable to varying degrees.
Do not use “pure” antifreezes in heating circuits. Since undiluted anti-freeze compounds are aggressive and tend to stimulate corrosion, they are diluted with water
The owner should take into account that non-freezing fluid must be changed periodically, which is fraught with additional costs.
Some models of boiler equipment have specific recommendations on the use of a coolant of a certain brand. If you use a liquid of a different composition, then you can lose the warranty on the boiler.
Overview of popular coolants
To protect ourselves, we deal with each type of coolant in more detail.
Option # 1 - water with additives
70% of modern systems use water, including its modified formulations using additives.
What explains this popularity:
- complete harmlessness - leakage can only cause domestic difficulties;
- highest heat capacity - about 1cal / g * C (each liter of water is able to transfer more heat than any other liquid);
- low cost and availability - water has a minimum cost compared with non-freezing compounds. At any time, the water system can be replenished without significant investment of time, labor and money.
True, it is undesirable to replace the water in the heating circuit without a good reason. When heated, it is freed from salts and oxygen.
The water that has boiled over several times in the boiler does not already have the composition and amount of salts that it was when it was poured into the system. Unlike the new portion, it is practically devoid of free oxygen.
Do not often change water in heating circuits so that scale does not settle on the pipe walls and the inner surface of the valve
The flip side of the coin is as follows:
- It has a relatively high freezing point, therefore it is impossible to leave the water heating system unattended (otherwise, when freezing and expanding, water can break pipes and radiators);
- The salts contained in the composition can provoke deposits on pipes and heating elements, which reduces heat generation and overall system efficiency;
- Water is an oxidizing agent, and oxygen dissolved in it can cause corrosion of metal heating elements, including radiators.
There is nothing to be done with the freezing temperature, but other negative properties can be significantly reduced. For starters, you can reduce the concentration of salts using softening. Reduce the amount of bicarbonate salts by boiling.
Sodium orthophosphate, which can be bought at the store, softens the water. In this case, you need to remember about the right dosage, because excess reagents can adversely affect the thermal properties of water.
In order not to be confused with the dosages, you can use distilled water, but it will cost an order of magnitude more expensive. Now you don’t have to worry about the radiators clogging with scale. To cheat and save, you can use melt or rain water.
It is already distilled naturally. But its purity can only be partial. It could well be saturated with atmospheric pollution, but in any case it will be much softer than water from wells, wells or a tap.
In order to maintain the technical condition of pipes, fittings, equipment, it is better to pour distillate into the heating circuit. Distilled water is also best served after emergency draining and system repairs.
Manufacturers offer distilled water enriched with inhibitory additives. They significantly reduce the likelihood of corrosion.
Also, surfactants are introduced into such a distillate. Their content in water minimizes the formation of deposits on the inner surfaces of radiators.
Surfactants cause existing deposits to exfoliate (followed by their removal from the system using a filter), and also reduces the chemical activity of water. As a result, all gaskets and seals will last longer.
Option # 2 - non-freezing antifreeze
Even distilled water with an optimal set of additives is not without its main drawback - freezing at 0 degrees Celsius. Special fluid for metal radiators does not have this flaw, in addition to having a lower crystallization temperature.
Low temperatures act differently on antifreeze than on water. Even if the minimum operating values are exceeded, the liquid does not crystallize and does not expand, but turns into a gel-like substance. Therefore, pipes and radiators are protected from deformation and damage.
As the temperature rises, the consistency of the thickened antifreeze becomes more liquid, the flow rates increase, although in the normal state they are 15% lower than that of the traditional rival - water.
The coolant is delivered in two modification varieties: 1 - with a freezing temperature in undiluted state -65 ° and the second option -30 °
Concentrated non-freezing composition can be diluted according to the manufacturer's instructions, taking into account local climatic conditions. To obtain a liquid with a freezing limit of -30 ° diluted with water by half, for -20 ° part of antifreeze is mixed with two parts of water.
Most formulations can withstand up to -65 degrees. In most areas of the north and middle zone, the temperature rarely drops below -35, so antifreeze is often diluted with distilled water, lowering the threshold to -40.
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Advantages and disadvantages of antifreeze
Features of heating with antifreeze
Filling the heating system with antifreeze
The use of antifreeze in warm floors
Faster seal wear
Failure of galvanized pipes
Antifreeze options for heating systems
Manufacturers of high-quality solutions make the composition as stable as possible, so it can last up to 5 years. After that, its full replacement will be required.
To achieve these properties, I had to sacrifice some of the benefits that water has:
- heat transfer of antifreeze is 15% lower, sometimes this may entail the need to install additional radiators or sections;
- may contain toxic substances, therefore it is impossible to use antifreeze in 2 circuit systems, where the composition can get into the hot water supply circuit;
- high fluidity compared to water, due to which it is necessary to use specific seals that can prevent leaks;
- increased viscosity, which will require the use of a more powerful pump - recommendations for choosing a pump and an overview of the top ten models we reviewed here;
- a higher expansion coefficient will require the installation of a larger expansion tank.
When using all types of antifreeze, it is impossible to carry out the wiring of heating with galvanized pipes, as in contact with them, the nezamerzayka loses some of its original beneficial properties.
It should be remembered that to fill the heating circuit should use a composition that is produced specifically for heating systems. Liquid for car engines cannot be used for this purpose
The use of non-freezing liquids as coolants forces us to make changes to the design of the heating system. Due to the viscosity of antifreeze, it transfers heat more slowly to heating appliances, so it is better to increase the number of sections of radiators or purchase appliances with a higher heat capacity.
It is still necessary to reduce friction in pipelines by replacing fittings with analogs one size larger than those used in water circuits.
Modern non-freezing liquids, depending on the composition, can be divided into three main types:
- glycerin;
- based on propylene glycol;
- based on ethylene glycol.
We will consider each separately to choose the most suitable option for existing equipment and conditions.
Option # 3 - ethylene glycol non-freezing bun
One of the most popular antifreezes takes its place of honor on store shelves due to the most affordable price in view of the simple production process.
The liquid contains about 4% additives that prevent ethylene glycol from foaming at high temperatures. This also includes inhibitors that prevent corrosion from attacking metal surfaces.
Due to the aggressiveness of ethylene glycol, the product is used only in diluted form to protect the inside of pipes and radiators.
Ethylene glycol is aggressive to pipes, devices and connections, toxic, but has good thermal performance
The main disadvantage of ethylene glycol is its toxicity. The minimum amount of this substance in the human body can cause serious health problems. Therefore, the entire heating system must have the highest degree of sealing.
Another gap in the use of ethylene glycol is constant temperature control. If the boiler heats the liquid to a temperature close to the boiling point, the composition will begin to decompose with the precipitation of a solid precipitate and the release of acids, which has a destructive effect on all heating equipment.
The specified antifreeze is suitable only for those systems where it is possible to precisely maintain the temperature regime, but not all boiler equipment is equipped with such an opportunity.
Option # 4 - propylene glycol based fluid
This is a more modern antifreeze, which got rid of some of the shortcomings of ethylene glycol.
Benefits:
- non-toxic - in the composition there are additives that are used in the food industry;
- can be used in dual-circuit systems, as even a random mix in the drinking circuit will not harm human health;
- higher heat engineering properties;
- operated 10 years;
- act in the heating circuit on the principle of lubrication, which reduces the hydraulic resistance in the pipeline and increases the efficiency of the system.
But, one drawback could not be eliminated - this is incompatibility with zinc. Special additives lose their quality when flowing through galvanized pipes. Another relative disadvantage is the twice as high price.
Option # 5 - glycerin antifreeze
Glycerin antifreeze is equated to water, as it is close to an ideal set of properties, but at the same time it is criticized. Opinions differ, so it makes sense to voice all the points.
Proponents of the glycerin composition reveal the following advantages:
- environmentally friendly and safe solution;
- wide operating temperature range - -30 + 100;
- when freezing expands to minimum values;
- not aggressive to galvanized pipes and radiators;
- cheaper than propylene glycol;
- service life of 7-10 years.
The glycerin-based variant is non-explosive and non-flammable. A significant plus is that it practically does not destroy seals.
Synthetic additives are introduced into the composition of glycerin-based antifreeze, due to which the corrosivity of the liquid is significantly reduced
Among those who are against this coolant, there are such arguments:
- a large mass, which causes an additional load on the pipes;
- lack of quality standards for glycerin mixtures;
- when overheating and evaporating water, it loses its properties, turning into a gel-like mass with hardenings;
- increased foaming;
- at temperatures above 90 degrees, it can begin to decompose;
- lower heat capacity compared to propylene glycol;
- due to its increased viscosity, it contributes to faster wear of equipment.
It is worth noting that in some countries where ethylene glycol is prohibited, there is no production of glycerin coolants at all. In view of the contradictions in the use of glycerin liquid, the responsibility for its use lies entirely with the owner.
Glycerol-based antifreeze - an option with a lot of advantages, but the cost and high viscosity make you think before you buy
Option # 6 - coolant for the electrode boiler
This type of equipment must be noted separately, because electrode boilers require a special type of coolant. In this case, the liquid is heated due to ionization from exposure to alternating current.
Antifreeze must have a certain chemical composition, which could provide three conditions: the correct values of electrical resistance, electrical conductivity and ionization.
Manufacturers of electrode boilers give their own strict recommendations on the use of specific brands of coolant. Therefore, it is necessary to select antifreeze with special care so as not to lose the guarantee.
Each model of the electrode boiler is limited to certain brands of coolant. When using a different composition, the manufacturer reserves the right not to fulfill the warranty
Recommendations for choosing a tool
It is necessary to take into account not only the characteristics of the coolants for the heating system, but also the configuration of the equipment in order to make the heating safe and efficient.
If you decide to focus on the use of antifreeze, let's consider the conditions in which its use is excluded:
- lack of a heating temperature controller in the boiler;
- when using seals from linen winding with oil treatment;
- in the heating circuit used pipes, radiators, valves with galvanized surface;
open heating system
Evaporation of water from a non-freezing liquid can change properties, and ethylene glycol vapors are toxic.
Compliance with the following rules will allow owners to get rid of a number of troubles with incorrect use of non-freezing fluids:
- in places of compaction, the linen tow should be lubricated with sealing paste;
- sectional radiators need to be sorted out to replace the seal with gaskets made of Teflon or paronite;
- Do not use automatic air vents (for bleeding excess air it is better to install Mayevsky taps for manual adjustment);
- radiators and pipes should have an increased volume and diameter;
- the presence of a circulation pump of increased power;
- install a diaphragm expansion tank with an increased volume.
Antifreeze is poured into the heating system only after a high-quality washing of the heating circuit, for which it is better to use special compounds. For the safety of all residents, experts recommend the use of propylene glycol.
The boiler must not be brought to peak power immediately after filling the system with coolant. It is necessary to raise the temperature in steps. This is necessary for the antifreeze to gain optimal performance and expand within normal limits.
To choose a suitable heat carrier, it is necessary to take into account the properties of pipes, boiler equipment and other factors.
When diluting the liquid with water, concentrations higher than -20 degrees must not be allowed. Excess water will lead to scale deposition and a change in the working properties of glycol. Only diluted with distilled water.
How to determine the volume of coolant?
The easiest way is to use a water meter or water meter. This is in almost every house or apartment with a centralized water supply.
Before starting measurements, the heating circuit must be completely emptied. Then the readings on the meter are taken, and the filling of the system with a small pressure of water begins. This is necessary so that there are no air jams that distort the readings.
As soon as the heating pipe is filled with water, you need to take the meter again. It must be remembered that 1 cubic meter is 1000 liters, and acquire the appropriate amount of liquid.
The second method is less convenient, but effective when there is no counter. The filled system is emptied through a measuring tank (tank or bucket of a certain volume). The main thing is not to get lost with the number of buckets.
Another method is mathematical. As initial data, the values of the volumes of radiators and expansion tank, pipe diameters, and the volume of the boiler heat exchanger are taken. Using simple geometric and arithmetic formulas, you can calculate the total volume.
Detailed examples of the calculation of each of the elements of the heating system we have considered in our following articles:
- Pipe volume calculation: calculation principles and calculation rules in liters and cubic meters
- Expansion tank for open heating: device, purpose, main types + tips for calculating the tank
The video will familiarize you with the opinion of a specialist on whether it is worth changing water to an anti-freezing liquid:
The above facts reveal a complete informational picture for each host, which is determined by the choice of coolant. He will know what kind of liquid he needs, what conditions are necessary for its use and how to create them.
What kind of fluid circulates in your heating system? Why did you choose this coolant and are you satisfied with its operation? Share your opinion in the comments section.
Or are you just determining the type of coolant, but you did not find the answers to your questions in this article? Ask your questions in the comments - we will try to help you.