Contents
In order for the pump not to turn on every time the tap is opened, a hydraulic accumulator is installed in the system. It contains a certain amount of water, sufficient for a small flow. This allows you to practically get rid of short-term switching on of the pump. Installing a hydraulic accumulator is a simple procedure, but you will need a certain number of devices – at least – a pressure switch, and it is also desirable to have a pressure gauge and an air vent.
Functions, purpose, types
In the water supply system of a private house without a hydraulic accumulator, the pump turns on whenever water flows somewhere. These frequent inclusions lead to wear of the equipment. And not only the pump, but the entire system as a whole. After all, every time there is an abrupt increase in pressure, and this is a water hammer. To reduce the number of pump turns on and smooth out the water hammer, a hydraulic accumulator is used. The same device is called an expansion or membrane tank, hydraulic tank.
appointment
One of the functions of hydraulic accumulators is to smooth out water hammer, we found out. But there are others:
- Reducing the number of pump starts. There is some water in the tank. With a small flow – wash your hands, wash yourself – water flows from the tank, the pump does not turn on. It will turn on only when there is very little of it left.
- Maintain stable pressure. This function requires another element – a water pressure switch, but they maintain pressure within the required limits.
- Create a small supply of water in case of a power outage.
Installing a hydraulic accumulator in a pit
It is not surprising that this device is present in most private water supply systems – there are many advantages from its use.
Types
A hydraulic accumulator is a sheet metal tank divided into two parts by an elastic membrane. There are two types of membrane – diaphragm and balloon (pear). The diaphragm is attached across the tank, the balloon in the form of a pear is fixed at the inlet around the inlet pipe.
By appointment, they are of three types:
- for cold water;
- for hot water;
- for heating systems.
Hydraulic tanks for heating are painted red, tanks for plumbing are painted blue. Expansion tanks for heating are usually smaller and cheaper. This is due to the material of the membrane – for water supply it must be neutral, because the water in the pipeline is drinking.
According to the type of location, accumulators are horizontal and vertical. Vertical ones are equipped with legs, some models have plates for hanging on the wall. It is the models that are elongated upwards that are more often used when creating the plumbing systems of a private house on their own – they take up less space. The connection of this type of accumulator is standard – through a 1-inch outlet.
Horizontal models are usually completed with pumping stations with surface-type pumps. Then the pump is placed on top of the tank. It turns out compact.
Principle of operation
Radial membranes (in the form of a plate) are used mainly in gyroaccumulators for heating systems. For water supply, a rubber bulb is mainly installed inside. How does such a system work? As long as there is only air inside, the pressure inside is standard – the one set at the factory (1,5 atm) or which you set yourself. The pump turns on, starts pumping water into the tank, the pear begins to grow in size. Water gradually fills an increasing volume, more and more compressing the air that is between the tank wall and the membrane. When a certain pressure is reached (usually for one-story houses it is 2,8 – 3 atm), the pump turns off, the pressure in the system stabilizes. When you open a tap or other flow of water, it comes from the accumulator. It flows until the pressure in the tank drops below a certain level (usually about 1,6-1,8 atm). Then the pump turns on, the cycle repeats again.
If the flow is large and constant – you are taking a bath, for example, – the pump pumps water in transit, without pumping it into the tank. The tank begins to fill after all the taps are closed.
The water pressure switch is responsible for turning the pump on and off at a certain pressure. In most accumulator piping schemes, this device is present – such a system works in the optimal mode. We will consider connecting the accumulator a little lower, but for now let’s talk about the tank itself and its parameters.
Large volume tanks
The internal structure of accumulators with a volume of 100 liters and above is slightly different. The pear is different – it is attached to the body both above and below. With this structure, it becomes possible to deal with the air that is present in the water. To do this, there is an outlet in the upper part, into which a valve for automatic air release can be connected.
How to choose the volume of the tank
You can choose the volume of the tank arbitrarily. There are no requirements or restrictions. The larger the tank, the more water you will have in case of a shutdown and the less often the pump will turn on.
When choosing a volume, it is worth remembering that the volume that is in the passport is the size of the entire container. There will be almost half as much water in it. The second thing to keep in mind is the overall dimensions of the container. A 100 liter tank is a decent barrel – about 850 mm high and 450 mm in diameter. For her and the strapping, it will be necessary to find a place somewhere. Somewhere – this is in the room where the pipe comes from the pump. This is where most of the equipment is installed.
If you need at least some guidelines to choose the volume of the accumulator, calculate the average flow rate from each draw-off point (there are special tables or you can see it in the passport for household appliances). Sum all these data. Get the possible flow rate if all consumers work at the same time. Then estimate how many and which devices can work at the same time, calculate how much water will go in this case per minute. Most likely by this time you will already come to some kind of decision.
To make it a little easier, let’s say that the volume of the hydraulic tank of 25 liters is enough to meet the needs of two people. It will ensure the normal functioning of a very small system: a faucet, a toilet bowl, a sink and a small water heater. In the presence of other household appliances, the capacity must be increased. The good news is that if you decide that the existing tank is not enough for you, you can always install an additional one.
What should be the pressure in the accumulator
Compressed air is in one part of the accumulator, water is pumped into the second. The air in the tank is under pressure – factory settings – 1,5 atm. This pressure does not depend on volume – and on a tank with a capacity of 24 liters and 150 liters it is the same. More or less may be the maximum allowable maximum pressure, but it does not depend on the volume, but on the membrane and is indicated in the technical specifications.
Pre-check and pressure correction
Before connecting the accumulator to the system, it is advisable to check the pressure in it. The settings of the pressure switch depend on this indicator, and during transportation and storage the pressure could drop, so control is very desirable. You can control the pressure in the hydraulic tank using a pressure gauge connected to a special inlet in the upper part of the tank (capacity of 100 liters or more) or installed in its lower part as one of the piping parts. Temporarily, for control, you can connect a car pressure gauge. His error is usually small and it is convenient for him to work. If this is not the case, you can use the regular one for water pipes, but they usually do not differ in accuracy.
If necessary, the pressure in the accumulator can be increased or decreased. To do this, there is a nipple at the top of the tank. A car or bicycle pump is connected through the nipple and, if necessary, the pressure is increased. If it needs to be bled off, the nipple valve is bent with some thin object, releasing air.
What air pressure should be
So the pressure in the accumulator should be the same? For the normal operation of household appliances, a pressure of 1,4-2,8 atm is required. To prevent the tank membrane from tearing, the pressure in the system should be slightly higher than the tank pressure – by 0,1-0,2 atm. If the pressure in the tank is 1,5 atm, then the pressure in the system should not be lower than 1,6 atm. This value is set on the water pressure switch, which is paired with a hydraulic accumulator. These are the optimal settings for a small one-story house.
If the house is two-story, you will have to increase the pressure. There is a formula for calculating the pressure in a hydraulic tank:
Vатм.=(Hmax+6)/10
Where Hmax is the height of the highest draw point. Most often it is a shower. You measure (calculate) at what height relative to the accumulator its watering can is, substitute it into the formula, you get the pressure that should be in the tank.
If the house has a jacuzzi, everything is more complicated. You will have to select empirically – by changing the relay settings and observing the operation of the water points and household appliances. But at the same time, the working pressure should not be more than the maximum allowable for other household appliances and plumbing fixtures (indicated in the technical specifications).
How to choose
The main working body of the hydraulic tank is the membrane. Its service life depends on the quality of the material. The best for today are membranes made of food rubber (vulcanized rubber plates). The body material matters only in membrane type tanks. In those in which a “pear” is installed, water contacts only with rubber and the material of the case does not matter.
What is really important in tanks with “pears” is the flange. Usually it is made of galvanized metal. In this case, the thickness of the metal is important. If it is only 1 mm, after about a year and a half of operation, a hole will appear in the metal of the flange, the tank will lose its tightness and the system will stop working. Moreover, the guarantee is only a year, although the declared service life is 10-15 years. The flange usually rots after the end of the warranty period. There is no way to weld it – a very thin metal. You have to look for a new flange in service centers or buy a new tank.
So, if you want the accumulator to serve for a long time, look for a flange made of thick galvanized steel or thin, but made of stainless steel.
Connecting the accumulator to the system
Typically, the water supply system of a private house consists of:
- pump;
- hydraulic accumulator;
- pressure switch;
- check valve.
Hydraulic accumulator connection diagram
In this scheme, a pressure gauge may also be present – for operational pressure control, but this device is not necessary. It can be periodically connected – for test measurements.
With or without XNUMX-pin fitting
If the pump is of a surface type, the accumulator is usually placed near it. In this case, a check valve is installed on the suction pipeline, and all other devices are installed in one bundle. They are usually connected using a five-pin fitting.
It has leads with different diameters, just for the devices used for tying the accumulator. Therefore, the system is most often assembled on its basis. But this element is completely optional and everything can be connected using ordinary fittings and pipe pieces, but this is a more time-consuming task, and there will be more connections.
With one of its inch outlets, the fitting is screwed onto the tank – the branch pipe is located at the bottom. A pressure switch and pressure gauge are connected to the 1/4 inch outlets. A pipe from the pump and wiring to consumers are connected to the remaining free inch outlets. That’s all the connection of the accumulator to the pump. If you are assembling a water supply scheme with a surface pump, you can use a flexible hose in a metal winding (with inch fittings) – it is easier to work with it.
As usual, there are several options, you choose.
Connect the accumulator to the submersible pump in the same way. The whole difference is where the pump is installed and where to supply power, but this has nothing to do with installing a hydraulic accumulator. He puts it in the place where the pipes from the pump go. Connection – one to one (see diagram).
How to install two hydraulic tanks on one pump
When operating the system, sometimes owners come to the conclusion that the available volume of the accumulator is not enough for them. In this case, a second (third, fourth, etc.) hydraulic tank of any volume can be installed in parallel.
There is no need to reconfigure the system, the relay will monitor the pressure in the tank on which it is installed, and the viability of such a system is much higher. After all, if the first accumulator is damaged, the second one will work. There is another positive point – two tanks of 50 liters each cost less than one of 100. The point is a more complex technology for the production of large containers. So it’s also more cost effective.
How to connect a second accumulator to the system? Screw a tee onto the input of the first one, connect the input from the pump (five-pin fitting) to one free output, and the second container to the remaining free output. All. You can test the circuit.