Reasons for water freezing in a well and ways to eliminate them. Thermal insulation materials, traditional and modern methods of source insulation. Well insulation is a complete sealing of the source in order to prevent water freezing. High-quality thermal insulation is achieved after excluding cold air access to the mine. How to avoid the problem of well operation in winter, we will learn from this article.
Well insulation materials and methods
With a close location of groundwater to the surface and in severe frosts, the operation of the well may be questionable. Theoretically, the source should not freeze, because in most cases the water table is located below the level of soil freezing. But in practice, there are other situations.
The diameter of the casing is usually small, and ice forms on the walls if there is no fluid movement. It reduces the opening and can rupture the trunk. Such a moment is especially unpleasant for wells with a pump. To avoid an emergency, they try to reliably cover the source from frost with the help of heat insulators.
Materials for insulating a well for water should have the following properties: availability, ease of installation, which should be performed without the use of special equipment, hygroscopicity, the ability to return to its size after deformation, for example, after heaving of the soil, cheapness.
Consider the following factors when choosing insulation:
- If the winter is mild and the temperature does not drop below minus 15 degrees, the well need not be insulated. Just in case, it is recommended to fill the upper part of the casing with natural materials: sawdust, straw, dry leaves, peat. They are cheap, easy to fit, but have a limited lifespan. After a year, the entire layer rots, and in the fall a new one has to be poured. Users note that rotting produces heat, which provides the well with a comfortable temperature.
- In harsh climatic conditions (the average temperature is below minus 15 degrees), synthetic materials are used for insulation: polystyrene, basalt mats, penoizol, etc. After installation, they must be carefully waterproofed, because when wet, they lose their qualities.
The choice of insulation method depends on the intensity of the well operation and the outside air temperature:
- If the water is pumped out continuously, it is sufficient to use conventional frost protection methods, which will minimize the likelihood of the source freezing.
- With the periodic operation of the well, there are few traditional methods of insulation, they will not prevent water from freezing in the well. To avoid trouble, special heating devices are used. For example, sensors are installed in the mine that measure the temperature near the shaft and, if ice appears on the surface, turn on an electric heater, say, a heating cable.
- In case of seasonal use of the well, its temporary conservation is carried out using a special technology.
There are several methods of mine insulation:
- A hole is dug around the trunk, and then it is wrapped or covered with heat-insulating material.
- To protect the well from frost, caissons are often used - boxes of various shapes dug into the ground. They are insulated from the outside or from the inside, while the casing pipes inside the structure are also covered with an insulator. The caisson can accommodate a pump, filters, water vending machines or other equipment for servicing a well and water supply.
- The head is sheathed with a wooden frame or covered with a wooden house on top. Lumber has poor thermal conductivity, so the source underneath will not freeze.
- In case of shallow freezing of the soil, peat, straw or sawdust are placed around the mine.
How to insulate a well with a caisson
A caisson is a large box dug into the ground above a well. It is designed to accommodate equipment for the water supply system of the site. It can also be used to protect the source from freezing. For this, the walls of the box are surrounded or covered with heat-insulating materials. Consider the most popular ways to insulate a well with a caisson with your own hands.
Selection and installation of a caisson for well insulation
The caisson is a round or rectangular box, which is buried in the ground below the freezing depth of the soil by 20-30 cm. The diameter of the product must be more than 1500 mm. Thus, an underground room is created above the well, large enough to accommodate a person servicing the equipment located in it or performing other work.
The box is usually installed during the construction phase of the well, but if necessary, it can be dug in at any time. There are several types of devices that differ in size, shape, material of manufacture, each of them has its own thermal insulation technique.
When choosing a caisson for well insulation, use the following information about the advantages and disadvantages of structures made of various materials:
| Material | Dignity | disadvantages |
| Plastic | Lightweight, no waterproofing required | Insufficient rigidity, cracking at low temperatures, only external insulation |
| Metal | High strength, no waterproofing needed | Requires protection against corrosion, high cost of the product, heavy weight, mandatory thermal insulation |
| Concrete | Great strength, long service life | Hygroscopic, waterproofing required |
| Brickwork | Great strength, long service life, thermal insulation properties | Complex installation, you need to have construction skills, mandatory waterproofing |
For insulation of reinforced concrete and brick products, it is recommended to use sawdust, peat, reeds and other natural ingredients. Plastic and metal caissons are wrapped with mineral wool, polystyrene, polyurethane foam, etc.
To install the box above the well, perform the following operations:
- Dig a hole around the shaft with a depth of about 2.2 m, which allows you to install the product in it. More precisely, the depth of the pit can be determined as follows: after installing a plastic or metal caisson in it, the upper part should protrude 15 cm above the ground, and after installing a concrete or brick structure, the top should be flush with the surface.
- Treat the metal box with an anti-corrosion agent. Cover the concrete with waterproofing.
- When insulating the building externally, dig a hole 1 m wider for ease of use.
- Pour a mixture of sand and gravel 10-15 cm thick at the bottom of the pit.
- Fill the floor with concrete and level it to the horizon using a level. The screed can be omitted if the ground is dry. In this case, sand and gravel will quickly absorb water if it gets inside the structure.
- After the mixture hardens, cut the casing so that there is 60 cm above the concrete.
- Install a caisson in the pit and put it on the horizon.
The box above the well can be made independently. Consider the sequence of building a concrete structure:
- Dig a hole that is sized for easy installation of the product. The depth of the structure must be such that after the construction is completed, the roof is flush with the ground. If equipment is installed in the structure for servicing the source, the well should be located closer to one of the walls of the pit.
- Pour a layer of sand and gravel at the bottom and level it into the horizon. It can be poured with concrete (if the bottom is wet) or left uncoated (if the bottom is dry).
- Assemble the formwork to fill the walls. You should get a structure with internal dimensions equal to 1.5x1, 5x2 m. The thickness of the caisson wall is 10 cm.
- Install a reinforcing mesh inside the frame.
- Fill the formwork with concrete.
- After the mortar has solidified, make a horizontal formwork (roof) with a hatch and also fill it with concrete.
- Wait until the solution hardens and waterproof the walls and roof from the outside.
- According to the dimensions of the opening in the horizontal overlap, make a hatch and close the opening.
Formation of an insulating layer on the caisson
Insulation of a well with a caisson is carried out in several stages. First, you need to decide where to place the thermal insulation coating - outside the caisson or from the inside, as well as choose a material for insulation. Outside the box, insulation is placed in the following cases:
- If necessary, save space inside the structure to accommodate equipment for servicing the well and water supply.
- When using sawdust, straw and other natural heat insulators.
- If the caisson is made of plastic, which bursts at low temperatures.
When the insulation is externally located, dig a hole around the box to the full height. The width of the annular pit should be such that it is convenient to work in it, usually within 1 m. The volume and sequence of the following operations will depend on the material of the heat insulator. After creating an insulating layer, fill the hole with earth.
Thermal insulation is often done by using mineral wool … If the box is plastic, there are usually special shelves for insulator blocks on its walls. Install a heater with a thickness of 30-40 cm in them and secure with wire, there is no need to leave a gap for ventilation. Fasten a plastic mesh around the metal caisson at a distance of 3-4 cm from the surface. Attach mineral wool with a thickness of at least 30 cm to it in any way. Wrap the protective layer on the outside and top with waterproofing foil, and then cover with a metal casing. Close the insulation very carefully, wet cotton wool loses its properties.
Also, the insulating layer can be done using polyurethane foam … Using special equipment, apply the substance to the walls of the caisson, from top to bottom. The energy efficiency of polyurethane foam is very high, so a layer of 30-40 mm will be enough. This material has good adhesion properties and adheres to any surface. Due to its special properties, the ventilation gap between the wall and the coating is not required to pass through.
Insulation of the caisson can be carried out using natural materials … At a distance of 40-60 cm from the walls of the caisson, assemble the wooden formwork around the perimeter of the pit. Treat lumber with antiseptic or paint to protect it from decay. Install a metal mesh around the pipe, leaving a gap of 4-5 cm between it and the wall of the caisson. Fill the formed space between the mesh and the formwork with sawdust, peat, straw or expanded clay. In the latter case, the insulation will last for many years - it does not rot or sag. Cover the insulation with a waterproofing cover on top. Tilt it away from the rainwater well.
For insulation from the inside, it is convenient to use Styrofoam … If the box is round, cut out the blanks in the form of discs. Their diameter should be slightly less than the inner diameter of the caisson. The number of discs must be such that their total thickness is equal to the depth of the structure. Cut holes in the blanks for the casing and install the foam inside the box, filling the caisson to the top.
If in your area the temperature is very low in winter, wrap the head of the well inside the box with mineral wool and fix it in this position with fired wire. Cover the insulation with waterproof plastic wrap. It is not necessary to fill the entire caisson cavity with insulation if the winter is mild. In the box, it is enough to install a thick foam plastic plug, placing it immediately below the upper inlet. Its diameter should be equal to the inner diameter of the structure. The disc can be made of plywood, and then sheathed with foam foam.
Cover the entrance cover of the caisson with mineral wool to keep cold air out. Be sure to waterproof the hatch.
Well insulation without caisson
In this case, the well is insulated by forming an insulating layer directly around the casing. To do this, dig a ditch around it 140x140 cm wide or more if it is inconvenient to work. Its depth should be greater than the level of soil freezing, usually 2 m. Further work depends on the type of insulator. After creating a protective layer, fill the remaining voids near the well with earth.
To insulate the well for the winter with your own hands, wrap the barrel mineral wool or glass wool and fix in this position with wire. Put a pipe on the head, the diameter of which is equal to the diameter of the well with mineral wool. Seal the gap at the top with waterproofing material.
For thermal insulation of a well shell polyurethane foam select the product by size. The inner diameter of the product must match the outer diameter of the casing. Place two pieces of shell around the casing and secure.
Well insulation heating cable considered a very effective method, but costly to the user. To do this, attach the heating element to the casing. Lay a product of high power in a straight line, low power - in a spiral, with a small step between the turns. Wrap the cable on top with mineral wool slabs. To protect the product from moisture, cover it with a waterproofing casing. The device can work continuously or turn on as needed.
The most economical way to insulate a well is to use sawdust … Pull the wire around the casing, leaving a gap of 4-6 cm per side, and attach the fine mesh to it. Make a cylindrical casing, the diameter of which is 60-80 cm larger than the diameter of the circle formed by the wire. Install the structure on the borehole head. Check that the gap between the casing and the net is the same around the circumference and fill it with sawdust. Cover the top of the annular gap with a moisture-proof cover. Bury the hole.
Casing pipe can be insulated peat, straw, expanded clay … The technology for performing the work involves the creation of formwork, and the sequence of work is the same as when insulating a well with a caisson.
A well that is not used in winter is recommended to be mothballed until spring. To do this, clean the casing from debris and deposits and disinfect. Pump out all the water from it. Close the barrel with a wooden cover, having previously covered it with plastic wrap. Fill the head completely with shavings or leaves and cover with a wooden or metal box. How to insulate a well - watch the video:
Operating the well in winter without thermal insulation can lead to breakdown of the water supply system and the appearance of cracks in the casing. High-quality insulation of the well for the winter allows you to operate the source at any time of the year and not raise the pump to the surface even in severe frosts.
