Vacuum solar collector – features of operation

Recommendation points

• Vacuum solar collector design
• Is it possible to get hot water all year round
• Will the solar collector work in cloudy weather?
• Strapping Tips
• Service
• Price table

What is the structure of a vacuum solar collector, is it possible to receive hot water from the sun all year round, will the collector fully meet the needs for hot water? How to properly tie the collector and does it need to be serviced? You will learn about this and much more from the article..

No one will refuse hot water for the price of cold water. Today it is possible thanks to the invention of solar collectors. The advantage of using them is that such a system begins to pay off from the first day of installation, since solar energy is completely free and its use is not taxed..

Of course, the payback period of such a system is difficult to predict, because everything depends on the daily volume of hot water consumption, the cost of the type of fuel, the alternative to which is the energy of the sun, the number of sunny days, the power of solar radiation in the region, and other factors. However, the payback period can rapidly decrease in proportion to the rise in prices for traditional energy sources, making the idea of ​​purchasing a solar water heater more attractive..

There are many types of solar collectors. This article will describe one of them, the most optimal for use in existing structures – a single-circuit vacuum solar collector with a remote storage tank.

Such a water heater is convenient primarily because all communications are outside the building and do not require a technical room, which is often impossible to equip in a residential building. It is enough to bring hot and cold water pipes to such a device to start using it. To expand the possibilities, you will also need a 220 volt network. But even without power supply, the collector will perform its main function.

Vacuum solar collector design

A direct-operated vacuum solar collector is essentially a boiler. Only the role of heating elements in it is played by copper heating elements located inside the storage tank. Their number depends on the volume of the drive..

Copper heating elements (heat pipes) are located in glass vacuum tubes, the design of which is similar to a thermos, which ensures minimal heat loss.

The heat pipes contain a non-freezing, easily boiling liquid. The solar energy absorbed by the selective coating of the vacuum tube is converted into heat energy, which is transferred to the heat pipes. The liquid inside the heat pipe boils and rises in the form of steam to the tip of the pipe.

There it gives up its heat to the water in the tank and, while cooling, condenses, flowing down to the bottom of the tube. This process repeats cyclically.

The copper tip of the heat pipe does not directly interact with the water in the drive. It fits into a brass sleeve that is screwed into the body.

The storage tank is constantly filled with water, which is under the main pressure of the water supply. The maximum allowable pressure for the tank is 0.6 MPa. Cold water is supplied to the bottom of the storage tank, heated water is drawn from the top. Due to this, the streams do not mix, ensuring a constant outlet temperature almost until the tank is completely drained. An automatic air vent is located at the top of the storage tank.

Storage tank diagram: 1 – housing casing, 2 – insulation layer, 3 – stainless steel tank, 4 – temperature sensor, 5 – air vent, 6 – hot water outlet, 7 – electric heating element, 8 – cold water inlet, 9 – barrier

Storage tank diagram: 1 – housing casing, 2 – insulation layer, 3 – stainless steel tank, 4 – temperature sensor, 5 – air vent, 6 – hot water outlet, 7 – electric heating element, 8 – cold water inlet, 9 – barrier

The control over the operation of the water heater is carried out using a multifunctional controller that analyzes and displays data on the water temperature, and also controls the electric heating element installed in the tank. The use of solar and electric energy allows the collector to provide uninterrupted hot water supply, even in cloudy weather.

Is it possible to get hot water all year round

In winter, the power of solar radiation decreases 5-6 times compared to summer. Therefore, a natural question arises – will a single-circuit vacuum solar collector work effectively in winter??

Despite the fact that all structural elements are installed outdoors, manufacturers of such collectors often position them as all-season, capable of operating at subzero temperatures. This statement is supported by the fact that an anti-freezing liquid is located in the vacuum tubes as a coolant, the remote tank has good thermal insulation, and a powerful electric heating element is inside it..

The water heater automatics are set so that when the temperature in the tank drops below 5 degrees, the automatic water temperature maintenance mode is activated. Provided there is an uninterrupted power supply, the water in the tank will not freeze, and in sunny weather, albeit less intensively, it will heat up. However, there are several features in the harness..

The first is an automatic air vent located at the top of the tank and well ventilated. With a strong minus, it can easily grab, or even break.

The second, perhaps most important, pipes of cold and hot water. In the absence of a water draw, even with the most effective thermal insulation of pipes, the water in them will gradually freeze. Therefore, in addition to maintaining the temperature of the tank, it is also necessary to ensure the circulation of water through the system. And this provides for the presence of a circulation pump and additional expenses for electricity, with the supply of which, especially in winter, failures occur.

On cloudy days, which are enough in winter, it may well happen that you heat the street, not the water. Therefore, for all-season use, dual-circuit solar collectors are better suited. In such devices, the coolant is antifreeze, and the water is heated through a heat exchanger installed in the storage tank, which is located in the room..

Will the solar collector work in cloudy weather?

The efficiency of a solar water heater directly depends on the power of solar radiation. Even on a cloudy day, a certain amount of solar energy breaks through the clouds, being absorbed by the collector’s adsorber. However, the power of such radiation is tens of times less than on a cloudless day. Therefore, you should not expect a significant increase in temperature from a water heater..

Strapping Tips

1. If you are not going to use the solar collector during the winter period, you will need an additional heating device. It will also be useful in cloudy weather (if you are not going to use the electric heating of the water heater). The solar collector must be connected in parallel with the auxiliary heater. For the convenience of switching between heaters, you can install a three-way valve to supply cold water to the devices. This will avoid mixing cold water through the inactive device to the hot water leaving the active.

2. All shut-off and emergency fittings should be located in a room with a positive temperature, this will help to drain water not only from the collector, but also from the outer pipes.

3. To compensate for the linear expansion of water during heating, it is necessary to provide a membrane expansion tank or a safety relief valve.

4. Install a check valve on the cold water supply to the reservoir. You can use a combined check valve with overpressure relief, the response setting is selected in accordance with the manifold’s passport. It is necessary to ensure the drainage of water from the discharge connection into the sewer.

5. A drain cock must be provided. It must be installed indoors to supply cold water after the check valve.

6. The storage tank can be used as a storage tank for chlorination or emergency shutdown. To do this, it is necessary to drain the drain not into the sewer, but into the hot water supply line. The water will be drained by gravity through the mixer. The pressure at the outlet of the mixer with such a drain will depend on the height of the tank relative to the drain point (1 m – pressure 0.1 kgf / cm²).

7. It is necessary to insulate all external connections to the water heater..

Piping scheme: 1 – three-way valve, 2, 5 – collector shut-off valves, 3 – check valve with a relief valve, 4 – drain cock, 6, 7 – shut-off valves of an additional heater

Service

Collector manufacturers often claim that their products are virtually maintenance-free and will last at least 25 years. Considering that the same processes occur in the storage tank as in the boiler, this can be questioned.

What work needs to be done periodically on the manifold to extend its life and improve efficiency?

It is advisable not to allow the collector to operate in stagnation mode (high heat load). Such modes arise when the demand for hot water is less than the collector is able to provide. As a result, the water overheats and boils. The collector is designed for such a load, although this reduces its resource. However, not all pipes are designed for temperatures of 100 ° and higher, and most importantly, it is dangerous to human health. It is advisable to assess your needs for hot water before buying a water heater, or to close one or more vacuum pipes for a while with an opaque material. This will reduce the capacity of the collector..

It is necessary to provide easy access to the place of installation of the collector and a convenient platform for maintenance..

Wipe the surface of the tubes periodically. Dustiness can reduce the capacity of the collector by 7%. It is enough to do this several times a year..

It is necessary to clean the inside of the storage tank from scale. To do this, you need to drain the water and dismantle the heating element. The procedure is the same as for cleaning a standard boiler. Frequency depends on water quality.

It is necessary to clean the sleeves in which the heat pipes are located from scale. For this it is necessary to dismantle the vacuum tubes. In order not to burn yourself, before starting work, you should close the tubes from the sun.

It is possible that a copper heating tube can get stuck in a brass sleeve. Then you will have to unscrew the tube together with the sleeve with a socket wrench.

You can remove scale with citric acid, vinegar or other chemicals..

Assembly is carried out upside-down. The rubber rings on the liner may need to be replaced. The heating tube should be lubricated with a heat transfer material for better heat dissipation and to prevent souring.

When draining the collector for the winter, it is advisable to cover its tubes with an opaque material. An empty tank on sunny winter days will overheat even more, which will negatively affect the rubber seals and prematurely disable the air vent.

It is necessary to periodically visually inspect the condition of the collector fasteners and the tightness of the connections.

Price table

A type	Tank volume, l	Number of pipes, pcs.	Cost, rub.
Ekoenergy BRJ2A / 9	90	nine	47065,00
Ekoenergy BRJ2A / 12	110	12	53725,00
Ekoenergy BRJ2A / 15	150	15	59,500.00
Altec SP-H-15	150	15	38775.00
Altec SP-H-20	200	20	44,000.00
Altec SP-H-24	240	24	52170,00
Altec SP-H-30	300	thirty	61390,00

The solar collector is a useful device, and most importantly, energy-saving. The collector shown in the article has a storage tank volume of 110 liters and heats it up to 65–70 ° С in summer, and up to 50–55 ° С in autumn and spring. However, like any heating equipment, it also requires maintenance. But, despite this, the solar collector is a step into the future, and if there is an opportunity, it is worth taking this step!