Expansion tank is one of the most practical equipment in central heating systems that prevents the bursting of water passage pipes by controlling the pressure. The structure of the expansion source is determined based on the type and location of their installation, and accordingly, this group of equipment is divided into two groups: open and closed expansion tank. Due to the great importance of this group of pressure control equipment in central heating systems, in the following we will introduce everything you need to know about the design and production of the expansion source. Join Seven Industrial Group, a manufacturer of expansion source and central heating and wastewater installations.
What is an expansion tank?
Increasing the volume of water and its pressure due to heat in heating and heating systems is one of the biggest problems that causes a lot of damage. In order to control this pressure and prevent the bursting of water pipes, tanks called “expansion tank” are used. In addition, in some cases and for various reasons, the water pressure in the heating system may be greatly reduced and as a result, its transmission will be disrupted. Another task for these tanks is to control the volume of water in the system, which is especially used in domestic hot water systems to transfer water to the upper floors of the building.
Types of expansion tank
Expansion tanks are divided into two groups of open and closed expansion tanks according to their operation and the general structure that is considered on each of them. These two types of tanks are completely different in terms of structure and shape, installation location and operation, which are:
open expansion tank
The pressure control in the expansion tanks is done in different ways. In the open tank type, the air pressure is used to balance the water pressure and the amount of steam in the boiler, as well as to compensate for the reduced water in the system. In order to achieve this goal, it is necessary to place the tank at a height of at least two meters above the heat exchanger in order to control the pressure in the best way and with the highest efficiency. It should be noted that the natural air pressure that enters the water in the tank is not high and cannot provide good results for high pressure environments. For this purpose, an open expansion tank is used in environments where there is little pressure.
Open expansion tank structure
The components of the open expansion tank include an open cylindrical tank with a stainless and anti-corrosion body and five inlet and outlet pipes that are installed on the roof and at a higher height than the heat exchanger.
How the open structure expansion tank works includes the following steps:
· Due to heating the water, its volume and pressure increase with increasing temperature and its volume in the tank increases.
· To balance the pressure and prevent water from overflowing, the tank tries to transfer water to other parts of the heating system with the air pressure applied to it.
· Due to the pressure applied to the water in the tank, its level decreases and water flows with proper pressure in the water pipes.
· As the pressure increases beyond normal and uncontrollable with the tank, some water and steam will escape from the emergency drain valves.
Advantages of open expansion tank
The open expansion tank has many advantages for supplying compressive force through the open air, the most important of which are the following options:
· Easy to set up, install and repair
· Low price compared to other types of expansion tanks
· High reliability due to drainage of excess water with emergency valves
· In other words, to buy a low-cost expansion tank in low-pressure environments, open tanks can be a good choice.
Disadvantages of open expansion tank
Despite the many advantages and reasonable prices that open tanks bring, the existence of some disadvantages makes them not always a good option for balancing water pressure and volume in heating systems. The most important disadvantages of this group of expansion tanks are the following options:
· Rust and corrosion due to exposure to rain and snow
· Waste of water due to emergency draining if the volume of water exceeds the allowable level
· More start-up costs due to the need for plumbing on the roof
· In addition, it should be noted that the use of this group of expansion tanks causes a large amount of energy loss due to direct contact with cold air in winter.
Closed expansion tank
Due to the limitations of open tanks, another type was designed and produced that has largely overcome the disadvantages of previous models. Closed expansion tank is another type of tank that, unlike the open type, is installed at a low height and at a short distance from the heating system boiler. In addition, the water inlet pipes must be located below the expansion tank. The volume inside the tank is divided into two parts in which inert gases such as nitrogen and water are separated and the water pressure is balanced by the gas pressure.
Closed expansion tank structure
Closed expansion tanks are generally divided into two groups, which are diaphragm and adjustable. The structure of the diaphragm closed expansion tank consists of a cushion which the circulating water of the heating system enters and is located above the tube of inert gases. As the water temperature increases and its volume and pressure increase, the tube changes and becomes slightly larger, and when the air pressure exceeds the allowable limit, the drain valves open and adjust the pressure to a fixed value.
Another type of closed expansion tanks are adjustable tanks, for which a constant pressure is considered in advance according to the volume of water and the conditions in the tank. As the water temperature increases, its pressure and volume increase, and after reaching the allowable limit, the drain valves open and the excess gas comes out. A very important issue in this type of expansion tank is the entry of gas into the water inside the tank and the creation of bubbles in it. The presence of bubbles in the water may cause problems due to the environment in which the wastewater is used.
Advantages of closed expansion tank
There are many advantages to the two types of closed tanks offered, which is why this type of tank is often used in industry. The most important of these are the following options:
· Use of closed expansion tanks in high pressure environments
· Long service life due to no rain or snow
· No need for plumbing due to being in the path of water pipes
Disadvantages of closed expansion tank
In general, compared to open tanks, in industry and even for domestic use, there is a tendency for closed tanks. But these types of tanks also have several disadvantages that must be considered when buying:
· Possibility of gas entering the water in the type of adjustable tanks and increasing costs due to the installation of ventilation systems
· High cost of production and design of closed expansion tank compared to open type
Expansion tank application
There is a need for heating systems not only in the home environment, but also in industry. Expansion tank can be used in all these environments in order to control the water and steam pressure in the tanks and also to provide the appropriate pressure in environments with low water pressure. The most common uses of expansion tanks are:
· Home hot water system
· Industrial engine rooms
· Expansion tank price
Expansion tank price
Due to the differences in the design and production of expansion tanks and the materials used in its various parts, different prices are offered for this equipment. The type of tank (open or closed), capacity, material of the tank body and other equipment used in them can all play a role in the price of the expansion tank. To inquire about the price of expansion tanks, you can use the communication channels mentioned at the bottom of the page and contact Seven Industrial Group.
Design and production of expansion tank
Each of the expansion tanks produced and offered in the market has different features according to the target environment that should be considered during the purchase. For example, in the production of expansion tank, it is possible to adjust its capacity for industrial environments, and as a result, using it in the home type can be a waste of energy and cost a lot. Seven Industrial Group, as a manufacturer of expansion tanks in various capacities, is ready to provide the necessary advice and guidance before purchasing this equipment.
Calculate the volume of the expansion tank
Expansion tank volume is one of the most important factors that need to be considered in the design process. In calculating the required and standard volume, it is necessary to pay attention to various factors such as the volume of circulating water in the heating system, maximum temperature, maximum expansion rate and temperature capacity of the boiler, diameter of inlet and outlet pipes. Of course, the above are only a limited number of these factors, and depending on whether the tank is open or closed, other factors may also play a role.