Heat carrier replacement in engineering systems of buildings
For our country, it is typical to use water as a heating medium for heating systems. This is due to the following factors:
- Water is the best carrier of heat.
- Water is not toxic, its vapors are always contained in the air, it can be discharged indefinitely both on the ground and in sewage systems.
- It does not require special training before disposal.
- Low cost, always available.
But despite all its advantages, there are a number of disadvantages that do not allow it to be used as a heat carrier everywhere. This is a high freezing point – 0°C.
When freezing, water expands that leads to the heating system failure. If water from the system is drained, the corrosion process inside it goes even faster, which in turn does not extend the life of the heating system.
Specialists of ASGARD-Service Company replace water in heating systems as follows:
Before water inlet, ASGARD-Service specialists will check the heating system for malfunctions. It is also necessary to calculate the amount of heat carrier in the system. There are special tables that allow to do this without difficulty. Calculation is made on 1 running meter of a pipe. Using these tables and knowing the diameter of the pipes, it is possible to calculate how much heat carrier will be required per 10 meters of the system.
Then the process of heat carrier inlet begins.
The first stage is a drain from the previous heat carrier system.
The heating system is cut off and turned off, the temperature of water in the system should reach ambient temperature. Further, our specialists drain the cooled water from the system through the lowest point. After all water has drained, the pressure in the system is stabilized by opening the valve at the top.
Then the system is flushed – with the help of a pump, flushing reagent is pumped into the pipes to completely remove deposits from the system, then it is washed out along with the deposits. The cycle is repeated several times.
Pumping into the heat carrier system
With the help of the pump, the heat carrier is pumped into the system until it flows from the top point – this is a sign that the system is full. Further ASGARD-Service specialists check the pressure in the system, check the serviceability of all measuring devices and carry out pressure testing of the system tightness.
The system is filled with ethylene glycol and propylene glycol in the same way.
Now heat engineers and owners of autonomous systems are increasingly using aqueous solutions based on ethylene and propylene glycol as heat carriers – they are also affordable, and its freezing temperature is lower than that of water. Due to the addition of additives and inhibitors, they do not give foaming and protect the system from corrosion. The percentage of the main component in the solution determines the thermal and physical characteristics of the heat carrier, namely, thermal conductivity, heat capacity, viscosity, range of permissible operating temperatures of the liquid ensuring safe operation of the heating or cooling equipment.
Advantages of ethylene glycol:
- does not allow the system to defrost;
- possesses good thermophysical properties;
- average cost.
The heat carrier and antifreeze on the basis of an aqueous solution of ethylene glycol with anticorrosive additives have the best characteristics; therefore, these low-freezing liquids are used in industrial air conditioning / cooling (chillers) and heating systems.
The main disadvantage is its high toxicity. At low temperatures it has a high viscosity, and when water is completely evaporated from it, the freezing temperature is on average equal to –13°C.
Propylene glycol features:
- does not require draining the system in winter;
- expansion volume is very small, which eliminates damage to the system. When the temperature drops to the temperature at which the heat carrier begins to crystallize, the crystallization process begins, and it thickens only when the temperature is lowered by another 5-7°C. The destruction of the system is excluded, since with a further decrease in temperature, the heat carrier (antifreeze) turns into a gel-like mass;
- has a very low freezing point – about –60°С – at full evaporation of water from its composition and cooling;
- non-toxic, environmentally friendly;
- has good thermophysical properties;
- not flammable and explosion proof;
- due to its low density, it requires less power consumption for pumping through the heating system.
Nevertheless, these heat carriers eventually lose their properties and require replacement. After replacement, all heat carriers are sent for recycling, and the system is flushed with plain water.
The optimal time for water replacement in the system is before each heating season. Distilled water is used for these purposes.
Ethylene glycol and propylene glycol manufacturers recommend changing every 2-3 years.
A significant disadvantage of ethylene glycol is its sensitivity to overheating. Even with a short rise in its temperature above normal, ethylene glycol thermally decomposes and gives an insoluble precipitate and acids. The precipitate forms carbon deposits on the heating elements, which in turn impairs heat transfer. Acids, in turn, have a negative effect on the metal parts of the heating system, which leads to corrosion. These factors lead to negative effects on the material of seals detachable joints. In addition, ethylene glycol has a high fluidity and, if corrosion occurs, the system will quickly leak. It is advisable not to forget about the foaming associated with the decomposition of additives – this can lead to the formation of air in the system.
Propylene glycol is similar in quality to ethylene glycol, but it has additional advantages – it is not poisonous and has a lubricating effect inside the system, which lowers the hydrodynamic resistance, moreover, its heat transfer is higher than that of ethylene glycol.
You choose which of the heat transfer fluid to prefer, but you need to take into account the features of the heating system.
Specialists of ASGARD-Service Company will advise you on the selection of the heat carriers depending on your needs and objectives.
Our experts carry out the replacement of the heat carrier based on ethylene glycol or propylene glycol in the cold supply system, as well as the replacement of the heat carriers in case of loss of its properties with antifreeze. Works are carried out by experts with years of experience, who understand all the technical nuances and are well aware of the chemical properties of substances.