It is enough to find out how a hydraulic accumulator for water supply systems is designed and functions in order to understand the enormous importance it has in systems for supplying water to private homes. This, as well as much more, will be discussed in today’s article.
Why is a hydraulic accumulator required?
Almost all owners of country houses are well aware of how difficult it is to ensure the normal and uninterrupted functioning of autonomous water supply systems. Disruptions in water supply are far from uncommon; they not only significantly complicate the life of a country resident, but can also cause the failure of expensive household equipment.
In some cases, even one pressure drop is enough to break a new dishwasher or gas water heater. And to avoid all these troubles, it is recommended to take care of the hydraulic accumulator, which is also known as a storage/expansion tank.
What is the purpose of the hydraulic accumulator? Let's take a brief look at its main functions.
- Ensuring constant pressure in the water supply system, protecting against pressure fluctuations. So, if several taps are used at the same time (for example, in the bathroom and in the kitchen) and pressure surges are observed, this may be accompanied by significant temperature fluctuations. And if at the same time you are washing dishes or, alternatively, taking a shower, then there will be a risk of getting burns. The hydraulic accumulator is designed to avoid such unpleasant situations.
- Providing residents with a certain volume of water in case of a sudden power outage (in cases where the pump does not work due to the lack of the latter). In this case, water will still be present due to the installed expansion tank. Exactly how much it will be depends on the volume of the container (100-200 liters or more).
- Protection against premature pump wear. As we just found out, there will always be a certain volume of water in the tank. And if you open the tap, then it will be used first, and the pump, in turn, will not turn on until the accumulator is completely emptied.
- Finally, it protects pipes from water hammer. These are often observed during the startup of pumping equipment, causing significant harm to the entire system at once.
So, the hydraulic tank is really very important for the normal operation of the water supply system of a private house, especially if it is located outside the city limits.
Video - The role of a hydraulic accumulator in a water supply system
Key types of expansion tanks
The devices described in the article, from the point of view of energy storage, can be of two types - with a mechanical storage device and with a pneumatic one. In the first case, operation occurs due to the load or the kinetics of springs. As for mechanical hydraulic tanks, they have numerous operational disadvantages (increased inertia or, for example, large sizes), and therefore are practically not used in household networks.
Note! It is also worth noting that mechanical devices do not need to be recharged or powered from external energy sources.
Devices with pneumatic types of storage devices are much more popular. They, working due to the compression of liquids under the influence of gas, come in the following varieties:
- piston;
- membrane;
- with a balloon/bulb.
If we consider a membrane accumulator for water supply systems, then it is characterized, first of all, by its small dimensions. They are convenient to use, and, moreover, in most cases they are found in private households. Finally, balloon models are also used relatively frequently. They are easy to install (you can do the work yourself) and maintain (if necessary, you can easily replace a bulb that has become unusable or the tank itself). Although we note that balloon tanks rarely need repairs - they are rightfully considered reliable in use and durable.
In addition, according to their purpose, all hydraulic tanks are divided into several categories:
- for cold water supply;
- for DHW;
- for heating systems.
Finally, according to the installation method, the tanks described here can be horizontal or vertical. Representatives of both categories function according to the same principle. But the former have separate fasteners with which the external pump is fixed. The latter, if the volume is more than 100 liters, are equipped with a special valve that allows air to bleed from the line.
Separately, it is worth highlighting the classification of tanks by volume. So, on the market you can find very miniature models, the capacity of which is only 2-4 liters, and real “monsters” with a volume of over 500 liters.
Note! If we talk about private houses, then it is recommended to use flexible tanks with a capacity of approximately 80-100 liters.
Video - How to choose the right hydraulic tank
Design features and principle of operation of the hydraulic accumulator
If we consider a membrane hydraulic tank, it is essentially a container with a special rubber gasket installed inside, which divides the tank into a pair of functional zones. The first zone contains water, while air or inert gas is pumped into the second.
In addition, the described device is equipped with a monometer - it shows what the air pressure is inside - and a special hole through which water flows. The latter is pumped into the tank using an electric pump. If the accumulator is equipped with automatic devices, then they themselves will turn off the pump when the pressure reaches the required value. As a result, the water supply to the hydraulic tank will stop.
Each consumption of water inevitably leads to a decrease in pressure in the tank. When it drops to the minimum permissible limit, the pump starts again and begins pumping water. It turns out that the hydraulic accumulator for water supply systems operates on a fairly simple principle. Anyone, even those far from all the intricacies of plumbing, can understand all this. Balloon tanks (and they are usually produced with a capacity of 100 liters) differ from membrane tanks in that the water does not come into contact with the walls of the tank. In such devices, the liquid enters the bulb, and after that it is used for its intended purpose.
Note! If the membrane hydraulic tank has a volume of more than 100 liters, then it is in any case equipped with a valve for bleeding air. If the displacement is smaller, then such an additional device is absent.
It is for this reason that during installation it is imperative to install a special tee or tap on the water supply (the latter will allow you to shut off the main line and then bleed off the air without any difficulty).
Video - Hydraulic accumulator device
Review of popular models, average market prices
There are many manufacturers of hydraulic tanks, and the cost of their products depends on a number of factors. Therefore, we will take a look at only the most popular models. For the convenience of site visitors, the information below is presented in the form of a small table.
Table. Characteristics and prices of popular models of hydraulic accumulators.
| Name, photo | Short description | Average market value, in rubles |
 1. Wester Line WAV 100 |
Membrane type device for use in cold water/hot water supply systems. It is characterized by a vertical installation method, an operating pressure of 5 bar and a capacity of 100 liters. The minimum permissible operating temperature is -10 degrees, the maximum permissible is +100 degrees. | From 6880 |
 2. Reflex Refix DE 100 |
Another membrane model in which it is quite possible to change the membrane. The installation is still vertical, and the operating temperature varies from -10 to +70 degrees. The hydraulic tank holds 100 liters and weighs 19 kilograms. | Around 11600 |
 3. Wester Line WAO 24 |
The device is of the same membrane type, designed for hot water supply/hot water supply. Maintains constant pressure and effectively compensates for hydraulic shocks. Horizontal installation, device volume is 24 liters, designed for operating pressure within 5 bar. | Around 1870 |
 4. "Dzhileks 50G" |
Horizontal installation device recommended for surface pumps. The operating pressure reaches 8 bar, and the capacity is 50 liters. At the same time, the device weighs only 8 kilograms. | 3700 |
 5. "Dzhileks 24G" |
The design characteristics are almost the same as the previous model. But the maximum volume in this case is 24 liters, and the weight of the structure is 5 kilograms. And the cost is lower. | 1500 |
6. Reflex Refix DE 80 |
The latest model for today is also a membrane model, designed for water supply networks. Installation type - vertical, the minimum permissible operating temperature is -10 degrees, the maximum permissible is +70 degrees. The volume of the hydraulic tank is 80 liters, and the total weight of the structure is 16 kilograms. | About 9370 |
Note! As you can see, the cost of tanks varies and depends not only on the characteristics or purpose, but also on the specific manufacturer. In any case, there is plenty to choose from, so let’s move on to the next stage – connection.
Overview of basic connection diagrams
There are several schemes for connecting a hydraulic tank to a water supply system, and the choice of one or another depends on the functions assigned to it. Today we will consider only the most common connection diagrams for the described device.
Scheme No1. With booster pumping equipment
Such pumping stations are used in situations where large water consumption is involved. In most cases, one pump in such devices operates constantly. As for the hydraulic tank itself, it is necessary here to reduce pressure drops in order to compensate for small water withdrawals or when activating auxiliary pumps.
In addition, this scheme is extremely common in systems with regular power outages to booster pumps, while the availability of water is essential. In this case, the situation is corrected by the supply of water in the hydraulic tank, which serves as a kind of reserve for a certain period.
Note! The greater the power and dimensions of the pumping station, and the higher the pressure it must provide, the larger the expansion tank, which plays the role of a damper, should be.
Now we move on to the next connection option for the described device.
Scheme No2. If you have a submersible pump
In order for the submersible pump to function long enough and uninterruptedly, it must be turned on about 5-20 times per hour, which must be indicated in the accompanying documentation for the device. If the pressure in the network drops to the minimum permissible value, the relay will turn on automatically, and if it drops to the maximum permissible value, it will turn off. Typically, the pressure indicator can drop to a minimum even if the water flow is insignificant (especially for small water supply networks), due to which the pump will turn on instantly, and then (after a few seconds) turn off when the water supply is replenished . This kind of operating mode does not affect the functionality of the pump in the best way, and therefore it may soon simply fail. To avoid this, you can use a hydraulic tank, in which there is always a certain supply of water and which always compensates for its small use; In addition, the tank prevents pumping equipment from being turned off/on too frequently.
Note! Also, the hydraulic accumulator, which is connected to the circuit, smoothes out a sudden increase in pressure in the line when the submersible pump is turned on.
As for the volume of the container, in this case it depends on the power of the pumping equipment and how often it is turned on; Other factors include the height of the pump, as well as exactly how much liquid is consumed per hour.
Scheme No3. With water heater
Let’s immediately make a reservation that a hydraulic accumulator for water supply systems is extremely important for a storage water heater. The fact is that water expands and increases in volume under the influence of high temperature; and due to the fact that the water supply system simply “doesn’t know how” to shrink, even the slightest increase in volume can cause failure of individual elements of the boiler. And the hydraulic tank will become a lifesaver in this situation too. Its capacity will directly depend on the volume of liquid in the heater, its temperature, and the pressure parameter in the network.
Scheme No4. Before the pumps
In this case, the hydraulic tank must be connected to the booster pump along the direction of fluid movement in the system. The device here prevents the consequences of a sharp drop in pressure if the pump is activated.
As for the volume of the expansion tank, in this scheme it depends not only on the total volume of water in the system, but also on the difference between the lower/upper pressure scale in the pipeline.
Features of installing a hydraulic tank
From all the information above, the obvious conclusion can be drawn that the hydraulic tank is not designed at all like traditional water tanks. It functions constantly, and its membrane is permanently dynamic. For this reason, installing a hydraulic accumulator yourself is quite difficult. The fastening of the tank must be as reliable as possible; vibration and strength reserves are required. You must also remember that the cross-section of the pipe at the inlet should under no circumstances be narrowed. And lastly, the first filling of the hydraulic tank should be done as slowly and carefully as possible, and the pressure should not be strong (this is in case the membrane has stuck together due to prolonged disuse - if the pressure is sharp, it will easily be damaged). Ideally, all air from the bulb should be removed before use.
How to set up a hydraulic accumulator?
So, you have purchased a hydraulic tank and successfully delivered it to your home. What to do with it next? First, find out what the pressure is inside the tank. As a rule, manufacturers pump about 1.5 atmospheres there, but sometimes (usually due to a leak) the pressure drops noticeably before the time of purchase. To check the correctness of your readings, unscrew the masking cap from a regular spool from the car, and then check the pressure.
How can this be done? As a rule, a pressure gauge is used for this purpose. Such a device, by the way, can be either mechanical (intended for cars, has an iron body) or electronic plastic (it is equipped with certain models of pumps).
Note! The pressure gauge you use must be very accurate, since even 1–2 atmospheres can affect the quality of operation of the accumulator. In a word, it is better to abandon the use of plastic devices altogether, because they are characterized by a fairly large error in the values.
Often we are talking about cheap Chinese devices, enclosed in a fragile plastic case. As for electronic pressure gauges, their performance can largely depend on temperature or battery charge level; moreover, they are quite expensive. In short, the best option is a simple car device that has already passed the test. It is also important that there are not too many divisions on the scale - this way you will be able to determine the pressure in the container more accurately. For example, if the scale is designed for 20 atmospheres, and you only need 1 or 2, then you can forget about extreme accuracy.
If there is less air in the tank, then, on the contrary, there is more liquid, but the difference between filled/empty hydraulic tanks is significant. But here it all depends on your personal preferences. If you require permanently high pressure in the system, then the container must have at least 1.5 atmospheres. But for ordinary household needs, 1 atmosphere is enough. In the first case, the pump will turn on more often, and in the absence of electricity, the reserve in the hydraulic tank may simply not be enough. In the second, you will sacrifice pressure, because using a shower stall with hydromassage is possible only with a full tank, and when it is empty, you will only have access to a bath.
In a word, decide what is more important to you, and then set the required mode (in other words, bleed off excess air or pump it up).
Note! You should not lower the pressure below 1 atmosphere, nor should you increase it excessively. A membrane filled with water at low pressure will come into contact with the walls of the tank, which means it will quickly fail. Excessive pressure will prevent the injection of the required volume of water, since almost the entire hydraulic accumulator for water supply systems will be occupied by air.
How to pump water into the hydraulic tank?
When everything is configured (including the pressure switch), the expansion tank can be safely connected to the network. When making connections, carefully monitor the pressure gauge readings. The maximum/minimum permissible value must be indicated on each hydraulic tank. The pump is disconnected from the network manually when the normal pressure of the tank and the maximum pressure of the pumping equipment are reached. This is observed when the pressure stops increasing.
As a rule, the pump power is not enough to pump the container to the maximum, but this is not particularly required, since pumping reduces the service life of both the membrane itself and the pump. Typically, the shutdown limit is set one or two atmospheres higher than the switching limit.
How to correctly calculate a hydraulic accumulator?
To determine the amount of water that can be used from the tank in the event of a power outage, you can use the capacity table below. This indicator will depend on how exactly the pressure switch is configured. So, the greater the pressure difference, the more water will fit in the reserve tank. Here is the table.
And finally, a few words about the operation of the device described in the article. Even the most primitive hydraulic tank, like any other device, needs care and attention. For example, you may be faced with the need to replace the membrane. You can learn how to do this correctly by watching the thematic video below.
Video - Correct replacement of the membrane in the hydraulic tank
That's all, good luck with your work!
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