Less and less often you can find gravity heating systems in private houses, this is due to the fact that most private backyards are equipped with modern, energy efficient boilers requiring forced circulation coolant. But the system in question should not be forgotten and it is necessary to be able to properly assemble and operate it.
Why is this needed? We will analyze it a little later. Perhaps among the readers there are people who need some educational program on the gravitational, "ancient" system. Let's get started:
Why does the coolant start moving in pipes without a pump?
A simple physical principle is used in a gravity system: Chilled water with a volume of one cubic meter, at a temperature of 30 ℃, has a mass of 995 kg, with a tail. And at a temperature of 90 ℃ it already has a weight of 965 kg. It turns out an approximate difference of 30 kg per cubic meter. Naturally, such a volume of water is rare in the system, but I think the principle is clear. The liquid begins to move due to the fact that a cold coolant, a heavier one, displaces a hot, lighter one. Using gravitational phenomena.
It turns out that in order for such a system to work well, it is required to raise the temperature of the liquid to the maximum, increasing the difference in weight.
How to properly assemble a gravitational system? Nuances
Below are some of the nuances of editing, which, if not followed, will lead to problems, wasted time and spoiled mood.
Pipe diameter. When assembling a gravity system, pipes with a large cross-section should be used. You can focus on the size of the pipe leaving the boiler. This will be the minimum value for horizontal inlet and outlet sections. In such pipes, the resistance to water movement is less, which will have a beneficial effect on the coolant flow during cooling. The narrowing of the supply and return pipes will stop the movement.
Observe the slope. Pipes with a slight inclination towards the movement of the liquid, as it were, "flow down" from the system. Reducing resistance to fluid flow, which is important. In addition, the air in the system will be collected in the expansion tank through the inclined pipeline. Also, if you want to drain water from such a system, then the observable slopes will allow you to do this without problems. But if there is a need to have a horizontal section of the pipe, then this can be done, in a normal, calculated system, it will not affect the movement of the fluid.
Observe the center line of the radiators. It must be above the centerline of the boiler. This is due to the fact that the cold coolant should not be lower than the firebox, that is, there is no need to waste energy by gravity to push the cold "pocket". And he should come immediately to the working chamber. Ideally, the boiler is installed at the lowest point available, a basement or a pit.
Insulate the main riser. To improve the performance of the system, it is recommended to insulate the supply pipe, which will lead to an increase in the fluid velocity. Especially important for unfinished, mowing systems. I think it's clear here without an illustration.
Expansion tank. Installed at the top, immediately after the boiler. The air released during the heating process will immediately collect in the expansion tank and will not walk through the system if the tank is placed in a different place.
The gravity system has low efficiency and requires constant water topping. In addition, compliance with the slopes of the pipes does not always have a beneficial effect on the external beauty of the premises. But these systems have their important advantage. They are non-volatile and will work in the absence of electricity. If this fact is not terrible for "advanced" villages and the private sector located near the cities, because there they react more quickly to emergency situations. Then this system is simply necessary for wilderness areas. Where a power outage can be for a week or more, which will lead to defrosting of the heating. And simply, if the "apocalypse" suddenly comes Ugh, ugh, then everyone will return to the old practices. Therefore, shake it on your mustache)