Expansion tank for water supply: hydro tank design, installation, calculation

Ensuring adequate heating and insulation is essential for keeping a home efficient and comfortable. However, the expansion tank for the water supply is a feature that is frequently overlooked but is just as significant. This tiny but essential part is essential to the overall operation of your water system. We’ll examine hydro tank design, installation, and calculation in this post, which will also highlight the significance of these components and how they help your home’s water supply run smoothly.

Let’s start by defining an expansion tank and discussing its importance. To put it simply, an expansion tank is a reservoir used in closed-loop systems like plumbing networks and heating systems to absorb excess pressure brought on by water expanding. In the absence of an expansion tank, the system’s internal pressure could rise to dangerous levels and possibly harm appliances, valves, and pipes. Therefore, adding an expansion tank to your water supply system is a proactive way to save expensive repairs and prolong its lifespan.

Let’s now investigate hydro tank design. These tanks usually consist of a sealed container with two chambers, one for water and one for air. The division is essential because it releases pressure from the system by allowing heated water to expand into the air chamber. A diaphragm or bladder is another feature of the design that keeps the water and air apart and from combining. This design reduces the need for maintenance while guaranteeing effective operation.

An expansion tank’s installation is comparatively simple, but there are a few things to carefully consider. First and foremost, the tank ought to be positioned such that it can readily adapt to variations in water pressure without creating any problems or risks to safety. To further stop the tank from moving or vibrating while in use, adequate support and anchoring are necessary. To guarantee compliance and best results, it’s also essential to adhere to local building codes and manufacturer guidelines.

An essential part of the installation procedure is figuring out the expansion tank’s size. The capacity of the tank should allow for the expansion of water without allowing the pressure to rise above acceptable levels. When choosing the right size tank, considerations like the amount of water in the system, the temperature range, and the maximum permitted pressure must be made. You can guarantee the efficiency of your water supply system and avert future problems by precisely estimating the tank size.

In conclusion, even though the water supply expansion tank might appear to be a minor part in the overall scheme of house maintenance, its importance cannot be emphasized. To guarantee the effectiveness, security, and durability of their water supply systems, homeowners should be aware of the design, installation procedure, and significance of appropriate sizing. The expansion tank can silently support the efficient operation of your home for many years to come, giving you comfort and peace of mind, with the right maintenance.

Hydro tank design	Installation
Choosing the right size and material based on water usage and system pressure.	Placement considerations, connection to the water supply system, and securing the tank.

Membrane tank as a hydroaccumulator

The expansion tank functions as a water accumulator in water supply systems, enabling the heating of a specific volume of water under pressure before using it for water delivery. In this instance, water is supplied without turning on the pump by using the pressure that is stored in the accumulator. In this manner, the accumulator prolongs the life of the pump by enabling you to turn it on less frequently.

The diaphragm tank accounts for water expansion when supplying hot water, just like it does in the heating system.

Expansion tank for water supply: device and functions | My well

Western membrane storage tanks

We have to learn today why the water supply system needs an expansion tank, how the membrane tank is set up, and how to connect it properly. But first, we explain the terminology and names of plumbing fixtures.

Down with confusion

Plumbing stores carry two different varieties of these devices that are colored differently from one another:

Image	Description
Expansion tank for hot water	1. Installed for heating – water supply expansion tanks are usually red and in full accordance with the name are designed to compensate for the thermal expansion of water or liquid coolant during heating. Liquids are virtually incompressible, and when they expand, the pressure in the closed circuit begins to grow at a catastrophic rate; the air cushion inhibits its growth.
Hydroaccumulators, or expansion tanks for drinking water supply systems – blue	2. Hydro-accumulators are blue in color (see the following video). Hydroaccumulators for water supply) . They allow you to create an autonomous supply of cold water, and act as a damper. That is, it dampens pressure surges during opening/closing of shut-off valves and switching on/off of the pump supplying water.

You can watch the video on this page to gain more knowledge about diaphragm tanks.

How are the water supply expansion tanks arranged?

A diaphragm tank is a steel container with a spool for pumping and a spigot for connecting to the heating system or water supply. It has two compartments, one for air and one for water, separated by an elastic membrane. In order to stop the tank walls from corroding, nitrogen is frequently used in place of air in the air compartment.

Water supply expansion tank design: an elastic membrane separates the steel tank into two sections.

Strangely, a hot water supply or heating system’s expansion tank typically has a membrane with higher thermal resistance. The expansion tank can be used safely as a hydroaccumulator because there are no additional design differences between it and the hydroaccumulator.

Schemes

Now, let’s examine in more detail the reasons why an expansion tank is necessary in the water supply system, using particular schemes as an illustration.

Two fittings installed on the boiler’s inlet pipe are typically used to strap the boiler:

Image	Description
Spring check valve	Check valve. It allows cold water from the water supply line to enter the storage water heater, but does not allow it to flow back out when the water supply is shut off.
Safety valve with water outlet to drain	Safety valve. Since the check valve turns the water supply system and the boiler into a closed circuit, when water is heated, the pressure in it begins to grow rapidly. When it reaches dangerous values, a safety valve discharges the excess water through a drainage pipe.

Consolidated body check and safety valves are frequently marketed as "boiler safety group," which is helpful.

Boiler valve

There is little to no loss of heated water as long as the boiler’s volume is small because the elasticity of the water pipe walls compensates for thermal expansion. However, hot water is released into the drain in large volumes—liters and tens of liters—which has a substantial impact on the expenses associated with DHW requirements.

No heated water is lost when the expansion tank is connected to the water supply system. The membrane tank holds its excess, and the circuit’s pressure rises slightly as a result.

The boiler harness’s diaphragm tank

When a water supply system has a boiler with a known capacity, what is the appropriate size for the expansion tank?

Typically, it is calculated to be 10% of the boiler’s volume. It’s true that water expands less than 10% at reasonable temperatures, but bear in mind that the water compartment’s capacity does not match the membrane tank’s total volume because some of that volume is taken up by air.

As a result, rounding up is actually used in practice: a 50-liter expansion tank can safely supply a 500-liter boiler with water.

Water expanding when heated

Water reserve

How can I use an expansion tank or hydroaccumulator to supply cold water so that I have water during its sporadic shutdowns?

There are just two very basic instructions to follow if you want to install the device yourself:

1. Connect the cistern spigot to any part of the water mains with a flexible or rigid supply line;

In the event of brief water shortages, the accumulator will keep you supplied with water.

1. Install a non-return valve at the domestic hot water inlet. It will not allow water to drain from the tank into the disconnected and discharged main water supply system.

Note that a membrane tank’s usable capacity is significantly different from its total volume. For instance, in the event of a shutdown, the 500-liter expansion tank in a water supply system can only hold 250 liters of water.

Water from a borehole

How is an expansion tank installed in a water supply system that draws water from a well or wells? Once more, it can be installed anywhere along the water supply system.

Membrane cistern in a self-sufficient water delivery system

Such a system comprises the membrane tank in addition to:

Image	Description
Line of submersible pumps Jileks	Submersible or surface pump. It raises the water and creates an excessive pressure that ensures the operation of sanitary appliances.
The check valve stands on the outlet pipe of the submersible pump	Check valve. It is placed after a submersible pump or at the suction connection of a surface pumping station.
Automatic relay for controlling the pump with pressure sensor	Automatic relay that controls the operation of the pump (i.e. turns it on when the pressure drops in the circuit and turns it off when the pressure reaches the upper critical value.

Plan for supplying water from a well

What level of pressure should be kept in the water supply system’s expansion tank?

Without knowing the pump control automatics’ settings, the response is not possible. The water supply expansion tank pressure needs to be about 0.2 atmospheres lower than the well water pumping pressure. In this instance, the pump will turn on before the open faucet releases the remaining water from the diaphragm tank.

If the water supply system’s expansion tank’s pressure drops below what’s required, how can the tank be pumped? Any air pump, be it from a bicycle, car, etc., can accomplish this. The diaphragm tank’s spool valve is linked to the pump hose.

Utilizing a car compressor to pump the diaphragm tank

Water from the tank

In garden associations where water supply is scheduled and where deteriorated water mains are frequently disconnected for maintenance, storage tank water supply is used. Using gravity to draw water from a tank mounted in the attic is the simplest way to supply the plumbing.

Gravity watersupply that draws from an attic-mounted tank of water

Nevertheless, there are three significant drawbacks to this plan:

1. Water supply is limited by the strength of the overlap;
2. The attic must be insulated and heated, otherwise the water will freeze in the first frosts;
3. The head in a gravity-fed water supply system is limited by the vertical distance between the tank and the faucet. Meanwhile, for normal operation of household appliances (flow water heaters, washing machines and dishwashers) need a head of at least 3 meters (0.3 kgf/cm2).

The following drawbacks are eliminated when using a pumping station to supply water from a tank placed in a basement, subfloor, or ground floor: the pump creates pressure, the ground temperature remains above freezing all year round, and the tank’s weight is unrestricted while it is standing on the ground or screed.

The basement floor has a tank installed with a water reserve.

What function does the expansion tank serve in the water supply systems in this scheme? Similar to a well’s water supply, this reduces pressure spikes and permits the pump to run at low water flow rates.

What should the expansion tank’s water supply connection diagram look like? The same applies once more to self-sufficient water supply from a well.

Plan for supplying water from the storage tank

But in reality, the water supply from the tank is typically placed in a surface pumping station, which consists of a pump, an automatic relay, a hydroaccumulator, and a pressure sensor all on one bed.

Pictured here is a pumping station.

Wiring diagrams for hydro tanks

The expansion tank for the hot water supply system is installed on the pump’s suction line, which is the portion of the circulation main that is closest to the water heater.

• pressure gauge, safety valve, air vent – safety group;
• a shut-off valve with a device that prevents accidental shut-off.

When water heating equipment is present in a plumbing system, the device replaces the expansion tank.

Installation plan for the DHW system: the hydraulic tank; the safety valve; the pumping apparatus; the filtration element; the check valve; and the other five 6-stopper

The primary guideline for installing the accumulator in the CHW system is to place it closer to the pump at the beginning of the piping.

The wiring diagram needs to include:

• check and stop valve;
• safety group.

Different connection schemes are possible. By normalizing the equipment’s operation and lowering the number of pump starts per unit of time, the connected hydraulic tank prolongs the equipment’s service life.

Installation plan for a well-equipped water supply system: 1 tank; 2 check valves; 3 stop valves; 4 pressure regulators; 5 pumping equipment control devices; Group 6: Safety

One of the pumps in the booster pump station scheme is always on. High water consumption homes or buildings are equipped with this system. Here, the hydraulic tank’s functions include absorbing pressure surges and installing a container with the biggest possible volume.

Installation of the expansion tank

Before beginning work, look for damage to the accumulator. The device is set up at room temperature in a soundproofed space. To gain entry to the shut-off valves, drain cock, etc., There should be a minimum of 0.6 meters separating the tank from the walls and ceiling.

Making provisions for the ability to fill the tank and empty the water in the room is also essential. Fasteners and the mounting location must be strong enough to endure the tank being filled to capacity.

Large tanks are mounted on legs, and wall mounts are used for expansion tanks up to 30 liters.

Pipes and aggregates should not be permitted to impact the accumulator, nor should it be subjected to mechanical or statistical stress. Rubber gaskets are used to secure the tank to the floor with screws. Install a check valve and a drainage tap at the hydraulic tank’s inlet.

The accumulator strapping process required the aforementioned steps, and it was completed on a daytime surface. It is necessary to enter the caisson in order to take further action.

It is still necessary to perform control tests and turn on the water supply circuit after the system has been assembled completely.

What to consider when buying

The membrane tank’s volume and capacity should not be disregarded; this is the primary factor to consider when choosing equipment. Details like the body’s shape, the size of the fasteners, and the connection to the water supply system are all equally important to pay attention to. You can steer clear of a lot of surprises during the installation process if you shop with the utmost caution.

Features of adjusting the hydroaccumulator

When water supply expansion tanks are first sold, they often have the factory default settings, which include 1.5 bar of air compartment pressure. The manufacturer advises against deviating from the specified parameters, particularly in the direction of pressure increase, and the permissible pressure is always indicated on the label.

Close the shut-off valves and unplug the system from the power source before making any adjustments. Draining the water completely empties the membrane tank; only then can the water compartment be accurately emptied and a pressure reading obtained.

Next, a precise pressure gauge is used to take the pressure readings. This is accomplished by approaching the device and removing the ornamental cap from the spool. Excess air is pumped or vented to bring the pressure into compliance if it is not the required pressure.

Since the manufacturer prohibits deviating from the suggested pressure values, it is imperative to choose appropriate equipment during the design phase, ensuring that its parameters do not clash.

The manufacturer fills the gas compartment of the tank with an inert gas (like dried nitrogen) before adjusting the pressure within. By doing this, the internal surface doesn’t corrode. In order to raise the pressure, users are also encouraged to use technical nitrogen.

Adjusting the tank pressure in the water supply system

When the pump is started, the pressure in the closed tank is always set to be 10% lower than the pump’s starting pressure. The water pressure can be changed by varying the pressure inside the apparatus. More water can be held in the tank the lower the gas pressure is (but not below 1 bar).

When the tank is full, the pressure will be strong, and when it is empty, it will become increasingly weaker. Set the pressure in the chamber with gas or air to 1.5 bar or less to guarantee a powerful and steady flow of water.

A relay is used to control the water pressure in the water supply. These values must be considered when adjusting the pressure in the expansion chamber.

Adjustment of the water tank in the water heater harness

When using an expansion tank for hot water supply, it must be empty at first. The device’s pressure is adjusted to be 0.2 more than the pump’s upper switch-off threshold.

For instance, the pressure in the expansion tank’s gas compartment should be set to 4.2 bar if the relay is configured to turn off the machinery at a pressure reading of 4 bar.

The tank, which is installed in the water heater piping, is not used to sustain pressure. It is intended to make up for expansion caused by heated water. There will always be water in the tank if the pressure is adjusted lower.

How to choose the right device?

The primary feature that guides the selection of equipment is its volume. All of the following elements must be considered:

• Number of people using the water supply system.
• Number of water intake points, which include not only showers and taps, but also household appliances such as washing machines and dishwashers.
• The probability that water will be consumed by several consumers at the same time.
• Limit the number of start-stop cycles in one hour for the installed pumping equipment.

Experts advise selecting an expansion tank based on the following indicators:

• If the number of consumers does not exceed three people, and the installed pump has a capacity of up to 2 cubic meters. m per hour, a tank with a volume of 20 to 24 liters is selected.
• If the number of consumers from four to eight people and the pump capacity is within 3.5 cubic meters. m per hour, a tank with a volume of 50 liters is installed.
• If the number of consumers more than ten people and the pumping capacity is 5 cubic meters per hour, choose an expansion tank with a capacity of 20 to 24 liters per hour. m per hour, choose an expansion tank for 100 liters.

When selecting the right model of the device should take into account that the smaller the volume of the tank, the more often the pump will be turned on. As well as the fact that the smaller the volume, the greater the likelihood of pressure surges in the system. In addition, the equipment is also a reservoir for storing a certain water reserve. On this basis, the volume of the expansion tank is also adjusted. It should be known that the design of the device allows the installation of an additional tank. And this can be done during the operation of the main equipment without labor-intensive dismantling work. After installation of the new device, the volume of the tank will be determined by the total volume of the tanks installed in the system.

When selecting an expansion tank, special consideration should be given to its manufacturer in addition to its technical features. Seeking affordability may lead to far more substantial expenses. The majority of the time, models drawn in by their low cost are produced using the least expensive materials, which aren’t always of excellent quality, as experience has shown. The quality of the rubber used to make the membrane is particularly crucial. This directly impacts the water quality that comes from the tank as well as the tank’s service life.

When purchasing a tank with a replaceable membrane, the cost of the consumable component must be mentioned. Frequently, dishonest manufacturers greatly overestimate the cost of the replacement membrane in their quest of profit. It will be more appropriate in this situation to use a different company’s model. Large manufacturers are typically willing to take accountability for the caliber of their output because they place a high emphasis on their brand. Therefore, it makes sense to start by looking at these brands’ models. This is Reflex, Zilmet, Aquasystem (Germany) and Dzhileks and Elbi (Russia).

Depending on the needs of the users, the expansion tank volume for the water supply can vary. You can install an extra device if you eventually need a higher volume.

Rules of water tank maintenance

The purpose of the expansion tank’s scheduled inspection is to measure the gas compartment’s pressure. Inspecting the valves, shut-off valves, air vent, and verifying the water pressure switch and pressure gauge are also essential. Perform an external inspection to ensure the integrity of the tank.

The pressure in the hydraulic tank should be checked and adjusted as needed during preventive maintenance.

Even though the device is straightforward, water supply expansion tanks still have a limited lifespan and are subject to malfunction. Common reasons include diaphragm rupture and nipple air loss. The frequent operation of the pump and the emergence of noise in the water supply system are indicators of impending failure. The first step in performing correct maintenance and troubleshooting on a hydroaccumulator is to comprehend its operating principle.

Device

How are the water supply expansion tanks arranged?

A diaphragm cistern is a steel container with a spool for pumping and a pipe for connecting to the heating system or water supply. It has two compartments, one for air and one for water, separated by an elastic membrane. In order to prevent cistern wall corrosion, nitrogen is frequently used in place of air in the air compartment.

Water supply device expansion tank: steel tank split into two sections with an elastic diaphragm

It may surprise you to learn that a hot water supply or heating system’s expansion tank typically has a membrane with higher thermal resistance. The expansion tank can be used safely as a hydro storage tank because there are no additional design differences between it and a hydro storage tank.

Whether it is necessary to install an additional expansion vessel

Good evening. I have a question regarding the installation of a bathhouse, specifically the wall-mounted gas boiler with two circuits.

24 kW Wolf. I persuade people that adding an extra expansion tank to the heating system is essential. As a result, we have 12–14 liters total—excluding the built-in 8 liters—with 1 coming from the boiler supply and returning to the collector group on 6 outlets for floor heating, covering an area of 70 square meters with heating. DHW and HTW agree with me. Eugene

The expansion tank’s necessary volume is determined through calculation:

VL stands for the heating system’s overall capacity, which includes the volume of heat carriers in the boiler, heating components, pipes, boiler coil, and heat accumulator;

Liquid expansion rate, expressed as E%;

D is the membrane expansion vessel’s efficiency.

D = (PV – PS) / (PV + 1), for its part

PV stands for maximum working pressure; in theory, 2.5 bar is sufficient for a private residence with an average size;

PS is the expansion tank charging pressure, expressed as m (0,5 bar = 5 meters; we use the static pressure value, which is determined by the differential between the heating system’s top mark and the tank’s installation level).

It is impossible to determine the precise volume of the expansion tank needed because we are unaware of the specifications of your heating system or the diameter and pitch of the floor heating pipes.

The length of each heating circuit can be determined by the designations on the supply and return pipes connected to the comb. During manufacturing they are marked in meters. By subtracting the smaller value from the larger value, you can find out the length of the loop. Knowing the total length of all pipes and their diameter, it is possible to determine the volume of liquid in them. The amount of the heat carrier, which can hold the boiler, is indicated in its technical passport. If there is a heat accumulator, water heater, the data should also be taken from the instructions for the equipment. You do not mention heating batteries, but if they are present, it is also necessary to calculate the volume of liquid both in the heat supply devices and in the supply pipes. Add up the obtained figures, this will be the total capacity of the system. Knowing this, you will be able to calculate the volume of the expansion tank on your own.

Using the boiler capacity as a guide, one can estimate the volume of an additional expansion tank and determine if it is necessary. The average in a circulating heating system without an extra heat accumulator is:

• for convector heating – 7 liters per 1 kW of boiler output;
• for radiator – 10,5 l/kW;
• for underfloor heating – 17 liters/kW.

According to your description, the system’s approximate volume in our instance is 17 l/kW x 24 kW, or 408 liters.

We use the following values, figuratively speaking, for an approximate calculation: PV is equal to 2.5 bar, PS is equal to 0.5 bar (the height between the top point and the cistern is 5 m), and E is equal to 0.029 (the water is 70 m)?

We compute using the following formulas:

D equals (0,285 – (0,5) / (2,5 + 1)

41,5 liters (V = (408 x 0,029) / 0,285

Acquire: extra vessel for expansion

Ought to be 41,5 – 8 = 33,5 liters in volume. It’s preferable to choose the larger version—40 liters—over the smaller one—when making this decision.

Eugene, you are correct of course: in this instance, an additional expansion accumulator is required. The estimate, made "by eye," speaks beautifully about it. But, a reasonably accurate calculation of the expansion tank’s volume and other system parameters is necessary to prevent instability and insufficient economy in the heat supply.

If you can, please provide a detailed description of your query, and our specialist will respond.

Hi, I’m using a gas boiler.

Is it feasible to add a second tank to the wall-mounted boiler, which already has one in the middle?

A vital component of maintaining the durability and effectiveness of your plumbing system is installing an expansion tank for your water supply system. Through comprehension of the design, installation, and calculation elements of a hydro tank, homeowners can efficiently regulate variations in water pressure and avert possible harm to their fixtures and pipes.

The ability of a hydro tank to adapt to changes in temperature-induced water volume is central to its design. The tank’s sealed air chamber permits water to expand and contract without unduly stressing the pipes. This design element lowers the possibility of leaks, bursts, and other plumbing problems by assisting in the maintenance of a steady water pressure throughout the system.

The expansion tank’s operation depends on its installation being done correctly. It ought to be mounted close to the boiler or water heater, ideally on the cold water line. Maintaining an efficient operation and preventing leaks requires making sure that the connection is securely fastened and oriented correctly. For best results, the pre-charge pressure in the tank should also be adjusted based on the static water pressure of the system.

The capacity of the water heater, the size of the plumbing system, and the anticipated temperature swings are some of the variables that go into determining the proper size of the expansion tank. Using online calculators or speaking with an expert can help you choose the appropriate tank size for your needs. It is important to calculate the tank size accurately because an incorrect size can result in inefficiencies or insufficient pressure relief.

To sum up, the expansion tank is essential to the upkeep of a functional water supply system. The design of the device facilitates adaptability to variations in water volume, and appropriate installation and sizing guarantee maximum longevity and performance. Through comprehension of these facets, homeowners can proficiently regulate variations in water pressure and protect their plumbing system from possible harm.

In understanding the ins and outs of heating and insulating your home, one vital component often overlooked is the expansion tank for water supply. This essential device plays a crucial role in maintaining optimal water pressure within your plumbing system, preventing damage from excessive pressure fluctuations. Understanding the design, installation, and calculation of a hydro tank is pivotal for homeowners looking to ensure the longevity and efficiency of their water supply system. From the basics of how it works to the specifics of where and how to install it, grasping these concepts can lead to significant savings in terms of both money and hassle down the line. So, whether you"re a seasoned DIY enthusiast or simply looking to be more informed about your home"s infrastructure, delving into the world of expansion tanks is a smart move for any homeowner.

Video on the topic

How to calculate hydraulic accumulator volume / Water hydraulic accumulator volume estimation

Review of the hydroaccumulator Jileks 100 liters with a through diaphragm