Heated swimming pool - do-it-yourself luxury and comfort

Boiler

This heating method is long, expensive, dangerous and is not suitable if the volume of water is large. Another disadvantage is the risk of spoiling the PVC if the structure is framed or inflatable. However, this method is often found among the advice of summer residents. Be sure to follow safety precautions while working.

• The boiler must be turned off when you place it in the container.
• Check the heating level only when you remove the plug from the socket.
• The boiler should not touch the walls. Especially if they are plastic. To do this, you can build a float from foam plastic, make a hole in it and insert a heating element so that the handle and wire are outside.

You can make several of these floats to make the process go faster. If the container is deep, you need to periodically stir the water so that the bottom layer also warms up.

Manual solar installation

You can heat the water in a swimming pool at your dacha using a regular garden hose. One end of it is connected to a filled reservoir, and the other to a filter pump. Then the hose is rolled up like a snake and placed in a lighted place. The water that gets into it becomes warmer and moves back. The disadvantage of this method is obvious - you need a hot, sunny day for everything to work. Watch a video with a similar water heater made of PVC pipe.

Boiling water outside the pool

It can be heated in large pots and buckets on the stove or fire, and then mixed with cold. The downside is that the method is labor intensive and is only suitable for small volumes. You can also pre-install a barrel on the site in which the water will be heated.

Water pipes

You need to attach a long hose to the hot tap. A costly method if you use it constantly. Plus, filling a large container can take a long time.

Solid fuel heater

You can quickly heat the water in a swimming pool at your dacha using firewood, peat, coal, and dry garbage. You will need a metal barrel, a powerful pump and a coil made of hollow pipe with long ends.

• A coil must be placed inside the tank. You can use a bent steel pipe or an old radiator (not cast iron).
• Attach metal pipe sections on both sides of the coil that extend beyond the tank.
• Place hoses on the pipes. On the one hand, cold water will be supplied through them using a pump, and on the other hand, already heated water will come out.

First turn on the circulation pump. When water enters the coil, light a fire under the tank or in it, depending on the shape of the boiler.

Solid fuel heaters are more economical and practical than the devices listed above. They will heat both small and large tanks even in cloudy weather. Suitable for stationary and inflatable structures. The disadvantages of this method are that constant monitoring of the firewood is required and it is impossible to adjust the temperature. You don’t have to make such a device yourself - a boiler with a heater can be found on sale. The video shows an example of a homemade barrel.

Let's start with the most common heating devices.

• Baths, saunas, swimming pools

  How to make a swimming pool at your dacha: 3 types of structures and methods of installing them

Electric heaters

Electric heaters are either flow-through or storage. The first ones are used most often, since they are small and easily heat small fonts. Tubular heating elements are installed inside the plastic structure. Cold water passes along them, warms up and is sent back.

The power of the devices is from 3.5 to 18 kW. For a small, inflatable tank, the smallest power is enough. True, a low-power device has a peculiarity - it is desirable that the incoming temperature be +18°. Pros: fast heating. Cons: high energy consumption, will not heat large volumes (from 35m³).

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Heat exchangers

The equipment operates from the heating system of the house and is a container with a coil inside. Boiling water from the heating system circulates in the coil. From the outside it is washed by cold water, which gradually warms up and flows back. The first time you connect it, it will heat up for about a day. The device then simply maintains the result.

Cons: long heating time during the first start-up, requires a disinfection system for uninterrupted operation.

Heat pumps

How to heat up an inflatable pool at your dacha quickly? For large framed and stationary hot tubs, heat pumps can be installed. They take heat from air, water or soil. They consume 1-1.25 kW and are connected to any electrical network. The equipment has one drawback - its high price. Sometimes the installation is complex, but simple models can also be found on sale.

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Solar collectors

These are devices of different shapes and sizes. Most often, rectangular panels are installed on sites. The second parameter is also very important when choosing a system. To heat a large volume and storage, you will need an impressive one. The work process is as follows. The pump pumps water into the solar system. After heating, it goes back into the tank.

The cost of equipment depends on its size and the presence of additional functions: touch sensors, temperature controller. The panel should be mounted in a well-lit place. Pros: Heating occurs quite quickly. The downside is low efficiency in cloudy weather.

Methods for heating pool water

There is a great variety of modern equipment for heating water, but from the wide range of all devices, five main types can be distinguished, which are more popular today. Among them:

• Solar heaters or collectors.
• Heat pumps.
• Electric heaters.
• Fuel heaters.
• Heat exchangers.

Solar collectors

This method is ideal for those who live in an area where the sun shines most of the time. The device will allow you to quickly heat any volume of water by increasing or decreasing the number of special modules that receive solar energy.

Solar heater is a safe and economical option for heating pool water

The presented system has a number of features:

• The solar heater is an environmentally friendly product;
• no additional temperature sensors are required for operation;
• Self-installation of the device will ensure a minimum of financial costs.

With all this, solar collectors can be divided into two groups.

Vacuum

They are panels with glass tubes installed on them, inside which similar tubes with a smaller diameter are located. The highly selective composition covering their inner surface favors the preservation of solar heat. Due to the fact that the heater operates by transforming a special liquid into steam, the water in the pool is heated evenly around the entire perimeter.

A vacuum manifold is an excellent option that will withstand any weather conditions

Flat

As a rule, collectors of this type are made in the form of breathable panels, which contribute to the complete heating of water up to 200 degrees, even in the absence of sunlight. Every crack and hole on the finished device is sealed with silicone.

The flat collector panel consists of:

• an absorber coated with black paint (it is used as an insulator of ultraviolet radiation);
• transparent screen made of corrugated polycarbonate;
• copper tubes, thanks to which the coolant is distributed;
• thermal insulation coating, which serves as an accumulator that retains the resulting heat.

The installation functions quite primitively: the absorber absorbs solar energy, after which it is converted into thermal energy and transferred to the water, heating it evenly.

The flat-plate collector heats the water in the pool while maintaining the optimal temperature

Heat pumps

A heat pump for heating water is a good and modern way to ensure comfortable swimming in warm water. It does not require a lot of electricity, and at the same time it is able to heat a large pool. The source of heat can be various natural components: from soil to warm air masses.

The principle of operation of a heat pump can be described as the operation of a refrigerator, only in reverse: it processes cold from the surrounding air, and the heat pump processes heat. Thus, releasing a significant amount of energy capable of heating a large volume of water in the pool.

Heat pump - operating diagram

Pros and cons (table)

Thus, heating a pool using a heat pump is quite effective, but only at temperatures above 5 degrees. Therefore, this type is widespread among owners of indoor swimming pools: the device heats not only the water, but also the air in the room.

Electric heaters

To heat water in small pools, it would be advisable to purchase an electric heater. Using such a system for large swimming pools will result in high energy bills.

An electric heater operates by pumping water through its body, inside of which there is a special heating part. Most often, the above-mentioned element is a non-insulated spiral or tubular heating elements (made of titanium or stainless steel). It is worth noting that the spiral is more resistant to salts and various impurities contained in water, which means the service life of the device increases.

The electric heater system contains 2 thermostats, thanks to which energy savings are achieved. The first maintains the water temperature, and the second provides heating elements with protection from overheating.

An electric heater is an easy and simple way to warm up the water in the pool

Pros and cons (table)

In addition, do not forget that most models of the presented type of heater require connection to a 380-volt network. It is possible to connect the system to a network with a voltage of 220 volts, but the efficiency and performance of an electric water heater will be halved.

Fuel heaters

Fuel heaters are one of the most economical options for heating pool water. It is worth noting that installing a system of this type is unprofitable, since it can also heat other objects on the site.

Basically, fuel heaters operate on oil products, gas, and solid fuel.

A fuel heater is considered one of the most dangerous options for heating water.

Undoubtedly, a wood-heated pool looks quite attractive. But in order to use fire-hazardous devices in everyday life, you need to perform a number of actions, namely:

1. Obtain special permission for installation.
2. Register the device.
3. Take fire precautions.
4. Install chimney and automation.

Having successfully completed all stages, you can begin installing the fuel heater. But before you complete the installation, you need to understand how the system works:

• It has a coil in which water is heated when fuel is burned.
• The heater is equipped with a special circulation pump, a filtration system and automation.
• The water heating process is controlled by sensors.

Heat exchangers

Heat exchangers for heating pool water are a fairly common type. The device is manufactured in the form of a large flask equipped with a coolant. It circulates inside the flask, redistributing high-potential energy evenly. As a result, water, heated to the desired temperature, continuously flows into the pool.

In order to maximize the effect of the heat exchanger, it is often equipped with thermal sensors with an automatic control unit. This allows the device to start working actively only when the water temperature drops below the set one. Thanks to this, the device saves energy and maintains a stable temperature.

Heat exchangers are a convenient way to maintain the temperature in the pool

Pros and cons (table)

How to make a heater?

There are a lot of design options for homemade heaters , and they are all manufactured using our own technology. Some heaters can be assembled using a minimum number of tools and materials, while others will require skills, knowledge, and ability to handle equipment and tools.

Solar

There are many design options for solar heaters. Let's consider one of the simplest types - a solar collector made of polypropylene hose.

You need to prepare:

• polypropylene hose (ideally black);
• fittings (flat tees and corner connections);
• plywood 8-10 mm thick for assembling the case;
• plexiglass or polypropylene for making a transparent cover;
• black paint.

In addition, you will need the following tools:

• sharp knife;
• measuring instruments (ruler, tape measure, square);
• a device for welding polypropylene (the easiest way is to use a construction hair dryer);
• electric saw or jigsaw;
• a fine-tooth hand saw for cutting clear plastic;
• ordinary tools (hammer, pliers, screwdrivers, etc.);
• brushes for applying black coating.

Assembly order:

1. Making a structure from a polypropylene tube that resembles an extension ladder - parallel tubes are connected using tees to two crossbars connected to the circulation system. It is necessary to ensure that there are no other openings other than the entrance and exit.
2. Welding the collector using a heat gun.
3. Assembling a plywood box into which the collector will fit quite easily (but without large gaps). Holes are made on opposite sides for the circulation pipes. The inside of the box is coated with black paint.
4. The lid is made of transparent plastic. It creates a greenhouse effect, allowing you to retain solar heat even on a windy day.
5. Place the collector inside, having first checked it for leaks. The inlet and outlet pipes are removed from the housing, the holes are sealed with sealant. The lid is installed and sealed.

This article will tell you what and how to make a solar collector for a swimming pool with your own hands.

How to make a solar collector from plastic pipes, video instructions:

Electric

To make it you need to prepare:

• Heating elements of the required power;
• housing (a used gas cylinder or fire extinguisher will do);
• connecting wires;
• switches for the control unit.

Tools you will need:

• grinder with cutting wheel;
• electric drill with a set of drills;
• welding inverter with electrodes;
• grinding attachment for an electric drill.

Assembly order:

1. 
   Manufacturing of the body.
   It must have holes for the inlet and outlet pipes and a connecting element for installing the heating element. As a rule, the top part is cut off and a platform with a pre-made thread is welded.

2. Nozzles are welded to the inlet and outlet openings for connection to the circulation piping.
3. Install the heating element, check the tightness, and, if necessary, seal problem areas with sealant.
4. A control unit is made (usually it is installed in the electrical panel or next to it). Connect the power wire for the heater, attach the cable to the electrical panel.

Read how to make an electric pool heater with your own hands here.

Fuel (wood)

The basis of the wood heater design is a metal coil. It is installed in a combustion chamber where wood will be burned. The inlet and outlet of the coil are connected to the circulation system.

You will need the following materials:

• copper tube (soft, annealed) with a diameter of 25-30 mm for making a coil;
• combustion chamber housing;
• connecting pipes for connection to the pool.

Tools:

• solder torch for copper tube;
• grinder with cutting wheel;
• welding inverter with electrodes;
• electric drill with a set of drills.

Manufacturing procedure:

1. The coil is wound according to a pre-prepared template. Try to lay the coils tightly enough so that there are as many of them in the combustion chamber as possible. This will improve heating efficiency.
2. A housing with a combustion chamber is made. It is welded from thick metal (you can use a ready-made large-diameter stainless steel pipe). It is necessary to immediately provide a door and grate for removing ash.
3. The coil is installed inside the housing using metal brackets. A cover with a chimney is attached to the upper part (it is best to attach it last, since the height should be at least 3-5 m).
4. They check the build quality and eliminate deficiencies.

You can test a wood heater only after connecting the coil to the water supply system. What and how to make a wood-burning pool heater with your own hands, read here.

Do-it-yourself wood-burning pool heater, video instructions:

Gas

To assemble a gas heater, you will need a ready-made gas burner (this is the best option), installed under a coil or a snake made of a metal tube. The design is close to wood-burning devices, but is more compact - there is no large combustion chamber, the fuel is supplied through a pipeline and does not require large volumes.

Materials you will need:

• ready-made burner (you can use a part from a gas boiler);
• body (homemade from a sheet of metal or ready-made, suitable in size);
• coil made of annealed copper tube;
• connecting pipes.

Required tools:

• welding inverter with electrodes;
• torch for soldering copper tube;
• grinder with cutting disc;
• electric drill with a set of drills;
• ordinary plumbing tools - file, hammer, chisel, etc.

Assembly order:

1. 
   The coil is made based on the dimensions of the burner.
   It is necessary to ensure that the leads are long enough so that the solder joints are outside the torch, at a sufficient distance from it.

2. Fix the coil on the burner. If its design does not allow this, the coil and burner are attached to the body, ensuring that these parts are immovable relative to each other.
3. Connect the gas supply pipeline with a shut-off valve.
4. The coil leads are connected to the circulation system.
5. Install the housing cover with the chimney.

Homemade gas appliances are dangerous because they do not have regulators or control systems for operating modes. Before starting assembly, it is necessary to carefully consider the design, and if in doubt, it is recommended to use another heating method.

Criteria for choosing a water heating device

The choice of a pool heating device must be approached with the utmost seriousness and be sure to pay attention to the following factors:

1. Pool view. There are two types of pools: in the house (closed) and on the site (open). The second option will require equipment with increased power, since the process of cooling water in the open air occurs several times faster.
2. Warm-up speed. The speed of water heating depends on the power of the device, however, more powerful devices are located in a high price category.
3. Pool volume. For a small pool, a system with average power and heating rate is quite sufficient, and for large tanks, the opposite is true.
4. Operational life. A device with high power and an increased degree of heat transfer will help you use the pool all year round. And for the summer period, especially on warm days, a device with average performance and heating speed will be sufficient.

The choice of water heater depends only on you!

From the above, we can draw a reasonable conclusion - the purchase of a specific water heating device directly depends on its technical characteristics and the selected type of pool.

Types of water heaters

Spiral water heater
The ideal option is a solution that does not consume any coolants or electrical energy. But in real conditions this is almost impossible to achieve. There are a large number of varieties of both commercial and independent developments.

Using a gas boiler. This option cannot be called economical, but thanks to it you can heat a large volume quite quickly. The disadvantage of such a system is the need for certain modifications. If you run pool water directly into the heater, it can clog it and cause scale to form on the heat exchanger. In turn, this will result in expensive repairs.

Wood-burning

Wood burning water heater. In this case, a small firebox is made, through which a coil is passed. Water passing through it heats up and returns back to the container. In this case, it is necessary to constantly monitor the state of the system and load firewood. There is also no possibility of continuous heating. At night, the water will lose its temperature.

Heat pump

Heat pumps. There is no point in installing such a unit just to heat the pool. This will be impractical in terms of productivity and material waste. It can be used when it is already built into the heating system of the whole house. The condition for its operation is the ambient temperature, which must be above +5°C.

Working principle of a heat pump

Electric heaters. In essence, they are similar to instantaneous water heaters for domestic use. The principle of operation is that the liquid passes through a coil that comes into contact with the heating element. This is how thermal energy is transferred. This solution is very uneconomical in terms of energy consumption. The power of the elements can reach or exceed 6 kW. If you use it for a long time, the electricity bill will cover all the joy of bathing.

Electric water heater

Solar water heaters. In such solutions, the sun acts as a heater. Its resource is inexhaustible, you don’t have to pay for it, so this solution can be considered ideal. But do not forget that during high clouds, when the rays are scattered, productivity drops, and at night it is completely zero.

Homemade solar collector

You can install or connect to any of the listed options yourself. Some can be assembled from the first screw. How to do this will be discussed further.

Pool water temperature: normal

In order for swimming in the pool to be pleasant and comfortable, the water temperature should have the following values:

• For active and sports games in the pool - 21–23 degrees.
• For adults - 25–27 degrees.
• For small children - 29–31 degrees.
• For older people - from 26 degrees and above.

Many factors are important for comfortable swimming: one of them is water temperature

Maintaining an optimal and stable water temperature in the tank is necessary so as not to harm yourself and your health.

Features and Features

A heated inflatable pool is an excellent option for relaxing in the country. Especially if you are a fan of starting the swimming season in April and ending it in October. And the location of your area does not offer warm sunny days for a long time.

The inflatable hydromassage pool with heated water has good quality characteristics. Since when using such a bowl there is not only a physical load on the material, but also exposure to water at elevated temperatures. Therefore, all inflatable models with such a bonus, in the form of a jacuzzi, massage and warm water, have:

• with a special coating of non-absorbable braided polyester threads coated with silicone. Plus a bottom that has an additional outer leatherette coating to prevent damage from plants and stones. Accordingly, such a bowl can be placed in any convenient place on the site, without preparation.
• has a unique water softening system, thanks to which hard water will not damage the filter.
• a powerful pump that pumps water up to 1700 liters per hour, trapping debris that gets into the water.
• heating system, capable of raising the water temperature to +40 in a few hours.
• has, depending on the pool model, up to 150 massage air nozzles along the perimeter of the pool for the flow of warm air bubbles.
• waterproof jacuzzi control panel.

The heated inflatable pool has a chlorhydrating system that disinfects the water with special salt. Staying in such a pool will bring a lot of positive emotions, as soft warm water has a beneficial effect on the skin and does not dry it out and soothes it. And bubbles from a heated outdoor Jacuzzi have a good effect on the circulatory system. In addition, they give a good relaxing effect.

Temperature conditions for swimming pools

Preparing for work

Making your own water heater for a swimming pool means you can save a lot on the purchase of expensive equipment. Using solar energy for heating is the best option to save both your money and thermal energy.

Material selection and tips

You will need quite a lot of materials to create a solar heater, but you should not skimp on them - all your costs will pay off in the first few weeks of operation. The most common wood can be used, for example, pine. Before using it, it is recommended to treat the surface with a special antiseptic to prevent rotting or the formation of pests. It is recommended that you initially buy the highest quality, albeit expensive, fasteners and adapters for assembling the manifold.

Tools

• Beam with a square section of 50 mm - 38 m.
• Plywood 12–15 mm thick - 5 m².
• Metal-plastic pipe with a diameter of 0.5 inches - 110 m.
• Plastic fasteners for pipes - 160 pcs.
• Carbon adapter for metal-plastic pipes of the male-female type - 60 pcs.
• Carbon adapter for metal-plastic pipes of the “female-female” type - 62 pcs.
• Adapter for fitting with a diameter of 0.5 inches - 105 pcs.
• Air outlet valve - 1 pc.
• Check valve - 1 pc.
• Tee with a diameter of 0.5 inches - 3 pcs.
• Drain tap with a diameter of 0.5 inches - 2 pcs.
• Submersible pump 3–4 m³/h – 1 pc.
• Corrugated hose - 2 pcs.
• Sheet metal - 5 m².
• Aluminum profile 12 cm high - 4 pcs.
• Steel corner (galvanized) 50x100 mm – 4 pcs.
• Glass 4 mm thick - 4 pcs.
• Black nitro paint - 5 l.
• Board 30x100 mm - 9 m.
• Ruberoid (or other rolled waterproofing) – 5 m².
• Paving slabs from 40 mm thick - 4 m².
• Self-tapping screws for wood.
• Plumbing fum tape.
• River sifted sand.
• Silicone sealant.

Boiler diagram

Various types of structures are used to heat water in the pool. The devices consist of a firebox, a heat exchanger, a housing and a chimney.

Metal units are mobile, have high efficiency, and do not require a solid foundation.

The simplest homemade device for heating water in a pool is a metal cylinder, inside of which a heat exchanger is laid along the walls: a stainless steel coil. Firewood is burned inside, water is supplied by a pump or flows itself into the pool located nearby.

Photo 1. To make a pool heater, you need a similar coil: this is a heat exchanger through which the coolant will circulate.

A metal potbelly stove with a built-in heat exchanger is more difficult to make, but it is more efficient. The firebox is located under a heat exchanger, which can be a mesh of welded pipes, a coil, ribs of cast iron batteries, or automobile radiators with sparse plates. Hot gases passing through the heat exchanger heat the circulating liquid.

In boilers based on the Buleryan long-burning stove, all the fuel is used to heat the passing water. Home craftsmen have long learned to make such devices from profile pipes and sheet metal.

Conclusion

For a country house, the problem with electricity and heating is often very acute, especially since solutions that you can do yourself take priority. Our latitude has a lot of sunshine even in winter. Therefore, using solar panels and a collector is the best way out. Buying a solar collector is expensive, but profitable, safe and environmentally friendly. Specialized companies will install it correctly and guarantee its use. They will explain how to properly handle the equipment. For greater efficiency and light absorption, basic care is the timely removal of dust from the surface of the glass.

A few tips for proper use

Compliance with the following recommendations will help increase the service life of flat water heaters.

• If the temperature drops below zero, you should stop using the pool. It is necessary to drain the remaining water from the collector.
• Scale builds up in the solar system openings over time. The pressure in the system decreases and the pump begins to work with increased load. Periodic cleaning with a soft brush and household detergents will help prevent this.
• Don't forget to wipe off dust from the glass. The efficiency of a collector with dirty glass drops significantly.

The most affordable heating option is from the sun

Sanitary standards establish the following water temperature indicators:

• children under 7 years old 30-32 degrees;
• children over 7 years old 29-30 degrees,
• adults 24-28 degrees.

In the conditions of central Russia, this method is not effective. To achieve a comfortable water temperature, it is necessary to use a water heating device

Craftsmen have already invented and implemented many simple and original solutions to this problem. Here are some examples.

What methods exist

In summer, the water in the pool is heated naturally. But when the temperature drops, you need to think about heating the water with special means. The easiest way is to install a factory-made heater. Electricity, gas or solid fuel can be used for operation. Next, we’ll take a closer look at how to heat water in a pool at the dacha.

To choose the right device you need to consider:

• Warm-up speed. In order to quickly warm up a pond, electric heaters are usually used. The power of devices directly depends on the price;
• Type of reservoir. Indoor pools are much easier and faster to warm up than open ones;
• Volume. The larger the volume of the reservoir, the more powerful and expensive equipment you need to buy;
• Frequency and seasonality of use. In order to regularly heat a pond, regardless of the season, you will need to install a device with an increased degree of heat transfer.

Electric heater

This is one of the simplest methods to heat the water in the pool. The liquid in the reservoir heats up when it passes through the tubes, which are heated by a dielectric. The device is very compact. The kit includes a small pump that forces liquid into the heating element. The temperature of the tubes themselves is constant, so the heating can be adjusted by adjusting the speed of water movement through the pipes.

Electric pool heater

This method is suitable for small pools, up to 30 m3. The advantage is the low cost of the heater itself, but its use is far from the cheapest, since it consumes a lot of energy.

Wood burning stove

In this chapter we will tell you how to heat the water in the pool using a regular wood stove. Of course, it will not be enough for a large volume of water, but for a summer bath or a small pond where children can splash and adults can relax after work, it will do just fine. The most pleasant thing is that assembling such a heater will not be difficult, and the money spent on heating is minimal.

The principle of operation of the unit is as follows: inside the firebox there is a metal coil, when a fire is lit in the firebox, water is pumped into the coil using a pump, passes through it, is heated by the hot metal and comes out on the other side, where through another pump it enters the pool.

The most important thing in this matter is to be able to calculate the speed of water flow so that it does not boil in the coil, but only heats up to the desired temperature. To do this, you need to choose pumps with high power - a standard pump or a circular pump will do.

To increase the efficiency of the system, it is recommended to install a chimney. The image below shows another variation of a wood heater.

You can make a fire simply in a coil. You can take this unit with you on hikes so that you always have hot water at hand. To drain water, you can take heat-resistant hoses or a piece of metal-plastic heating pipe.

User reviews from the Internet information space

In many user comments, the cornerstone in the operation of collectors is their direct dependence on solar activity. Orientation to the sunny side, angle of inclination and the presence of as many sunny days as possible are important components for the stable operation of a solar installation.

Users of prefabricated pools on the territory of a private house or cottage note the opportunity to lengthen the swimming season. It is recommended to use systems with flat collectors without separate heat exchangers. Pool water changes temperature by passing directly through the installation tubes. Such a system will be simple and low in price.

In northern territories with cold climates, flat-plate collectors practically do not receive good reviews. Despite their high cost, vacuum solar units are more widely used here. Due to low heat losses, they perform their functions better in heating pool water in cold latitudes.