The main points to pay attention to when choosing a liquid for the heating system:
Basis. The package always indicates which product is the main ingredient. Ethylene glycol has the highest freezing point. It has increased fluidity, so the sealing of the joints should be especially careful. On the other hand, there are never any problems with it in terms of circulation. But this coolant is the most toxic. Medium in price and a relatively new type – glycerin, it is less harmful, but requires replacement of gaskets with Teflon. The most expensive is propylene glycol, which is chemically neutral and resistant to overheating. A separate substance is oil, which has low antifreeze indicators, but allows it to be heated to higher temperatures.
Crystallization point. This is the number of degrees below zero, after which the fluidity of the product is lost. The indicator varies from -15 to -65 degrees, which is important to consider when choosing a coolant for use in heating systems in various regions with a cold and temperate climate.
Boiling point. Indicates when the antifreeze starts to foam. Some have it after 70 degrees. The maximum indicator is 115 º C. The later the liquid boils when it is overheated, the longer it will retain fluidity, the effectiveness of additives and continue to perform its main functions – to transfer heat.
Can be diluted with water. Some substances for heating systems can only be used in their pure form, while others are allowed to be diluted with ordinary water according to the table of the ratio of parts, depending on the winter temperature in the region. The second option is economically more profitable, as it allows you to fill the volume of the system with a smaller amount of antifreeze, and add the rest free of charge with water.
Term of service. A safe service life guaranteed by the manufacturer is indicated on each coolant. During this period, the agent will have a gentle effect on the seals and metal, as well as meet the specified crystallization and boiling characteristics. Some liquids last for 4-5 years, others up to 10, which affects heating maintenance costs.
Heat capacity. The more thermal energy a liter of liquid can transfer, the better. And here the undisputed leader is water, which has the maximum heat capacity. Table of the specific heat capacity of coolants:
Water – 4.218 kJ/kg*K;
Ethylene glycol – 2.2 kJ/kg*K;
Propylene glycol – 2.483 kJ/kg*K;
Glycerin – 2.43 kJ/kg*K.
Accordingly, Antifreeze for heating systems of a private country house can be made on the basis of one of two types of liquids:
– ethylene glycol;
– propylene glycol.
Ethylene glycol-based antifreeze can be described as toxic, but at the same time cheap, while propylene glycol antifreeze does not harm human health, but is more expensive.