In any private house, a stable, trouble-free water supply system is needed, with a normal pressure of water in the taps. It would seem: laid pipes, connected a pump for water supply - and use it. But it’s not so simple.
Firstly, when the water is turned on / off, it will constantly operate and quickly fail. Secondly, when closing the tap, the risk of water hammer increases - a sharp jump in pressure in the system - and possible rupture of pipes and their connections, damage to connected plumbing equipment (washing machines, water heaters ...).
In order to avoid such troubles, it is necessary to use equipment such as an expansion tank in the water supply system. What it is?
The expansion tank (hydroaccumulator) is capacity, which is used in the system of autonomous heating and water supply in an apartment building or private house. Its main task is to prevent the occurrence of increased pressure in a closed system filled with liquid, and thereby protect it from water hammer.
Types of expansion tanks for the intended purpose
- For heating. Designed for high temperatures (up to 120 degrees) and a pressure range (up to 4-6 atmospheres), typical for heating systems; made from materials not suitable for drinking water. Usually red.
- For water supply. It is made of materials that take into account the hygienic requirements for the quality of drinking water (rubber or rubber based on ethylene propylene, steel). Working pressure should reach 12 atmospheres, operating temperature - up to 80 degrees. Usually blue for hot water (white for hot water).
Tank types
- Tanks of open type. Installed in attics, roofs of buildings. The water pressure in the system is determined only by the installation height.
- Closed tanks - with an elastic partition (membrane), which divides the capacity of the device into two parts: for filling with water and for air.
Types of closed expansion tanks of membrane type
With stationary membrane:
- as a rule, these are containers of small capacity;
- when the diaphragm fails, it will be impossible to replace it;
- mainly used in heating systems.
With a replaceable diaphragm - balloon type (the balloon is also called a "pear"). Optimum for water supply for the following reasons:
- water enters directly into the pear membrane and does not contact the metal walls of the tank; accordingly, corrosion does not occur and the quality of the water does not change;
- the pressure necessary for the functioning of the system is easily pumped;
- the membrane is easily replaceable;
- devices of this type can have high capacity, which is very important for private home ownership.
Expansion tanks used in the water supply system are also called accumulators - this is due to their role in ensuring the functioning of the autonomous water supply in houses.
The principle of operation of the accumulator during water supply
Water is pumped from the source into the tank cavity to the maximum value set by the relay and stretches the membrane. The volume of air in the second cavity of the tank is thus reduced. Due to this compression, the total pressure in the system increases to the specified parameters and the pump turns off. At the time water begins to be used, air begins to press on the membrane and thus expel water from the accumulator.The excess pressure created in the air chamber of the apparatus will be enough for a certain period of time so that the flow of water (household appliances, washing dishes, etc.) occurs without starting the pump. As soon as the pressure in the tank reaches the minimum threshold preset for a particular water supply system, the relay will signal to turn on the pump and it will begin to refill the tank with water from the well (well). Then the cycle will repeat.
With a large flow of water from an autonomous water supply, the pump will work continuously, providing a point of water consumption directly.
The functioning parameters and the volume of the expansion tank, as well as the settings of the control sensors connected to it, are calculated according to certain formulas based on:
- pump characteristics
- pipeline installation project,
- operational requirements of equipment connected to the water supply system,
- estimated water consumption (how many people will use water, how often, how much),
- number of storeys of the building.
The role of the expansion tank
- Expansion tank helps create in the water supply system enough stable working pressureat which the optimum water pressure will be maintained both for the operation of all plumbing fixtures (water heater, washing machine, flush tank), and for comfortable use of tap water. Indicators of the necessary pressure in the air chamber of the accumulator are calculated for each of the autonomous water supply systems according to certain algorithms.
- Creates a supply of water and maintains a stable pressure in the water supply for a certain period of time. A power outage situation is not uncommon: the pump in this case stops working and then the accumulator acts as an emergency reservoir, water from which will flow under pressure for a while. In order to increase the supply of water in the house, you can additionally connect another expansion tank without dismantling and replacing the already installed one.
- Optimizes pump function: reduces the number of inclusions. The larger the accumulator volume and the higher the maximum pre-set pressure threshold in the tank, the less pumping equipment will operate. Thus, its wear and tear will be significantly reduced.
- It plays the role of a damper in water hammer. At any start-up of the pump, there is always a sharp jump in pressure in the water supply system - sometimes it reaches ten atmospheres. The result of such a sharp difference can be the rupture of pipes and fittings, valves; connected plumbing equipment and instrumentation may fail. The expansion tank in this case takes the shock load on itself: it dampens the wave power and the system is safe.
In cases where there are risks of exceeding the design pressure during a water hammer of 20 bar (the maximum permissible value), it is necessary to install the pipeline so that in its separate sections a separate damper tank can be installed for reliable protection against water hammer.
So, an expansion tank (hydraulic accumulator) in the water supply system protects it from water shocks, ensures the correct operation of all equipment and household appliances connected to the water supply, and creates a reserve supply of water.
