Gravitational home heating system: advantages and organization rules

The sim­plest solu­tion to this prob­lem will be the design of an ini­tial­ly non-volatile autonomous heat­ing sys­tem, in which there are no nodes con­nect­ed to the pow­er grid. As a boil­er, you can use units for sol­id or liq­uid fuels, as well as gas. Most often, a mod­el with an atmos­pher­ic gas burn­er and a mechan­i­cal con­trol sys­tem is used. Such boil­ers with a capac­i­ty of sev­er­al tens of kilo­watts are avail­able from many man­u­fac­tur­ers. You can find some­thing for every taste and bud­get, from domes­tic boil­ers worth 15–200 $. to import­ed ones worth 50–1000 $. These are main­ly mod­els for floor mount­ing; wall-mount­ed non-volatile gas boil­ers, such as IShMA-12.5 BSK (“Borin­skoye”), are a rar­i­ty, and here’s why.

The fact is that as an alter­na­tive to a sys­tem with a cir­cu­la­tion pump, a so-called grav­i­ty sys­tem with nat­ur­al cir­cu­la­tion is used. In it, the cir­cu­la­tion of the coolant occurs due to the dif­fer­ence in the den­si­ties of the heat­ed and cooled liq­uids. If we sim­ply con­sid­er the closed cir­cuit of the sys­tem, then the liq­uid heat car­ri­er is heat­ed in the boil­er and is dis­placed by a cold­er and denser liq­uid com­ing from the radi­a­tors. The grav­i­ta­tion­al pres­sure in such a sys­tem is pro­por­tion­al to the ver­ti­cal dis­tance between the con­di­tion­al heat­ing cen­ter (boil­er) and the cool­ing cen­ter (radi­a­tor) and the den­si­ty dif­fer­ence between chilled and hot water.

The grav­i­ty sys­tem is struc­tural­ly dif­fer­ent not only in the absence of a cir­cu­la­tion pump. It, for exam­ple, uses an open expan­sion tank locat­ed at the high­est point of the sys­tem. Hor­i­zon­tal pipelines are rec­om­mend­ed to be laid with a slope of 0.005 along the coolant (1 cm per 2 m of the pipeline). The entire cir­cuit is designed so that the small­est pos­si­ble hydraulic resis­tance occurs in it (from pipes of increased diam­e­ter).

In a grav­i­ty sys­tem with a sin­gle-tier arrange­ment of heat­ing devices, the boil­er must nec­es­sar­i­ly be locat­ed below the group of heat­ing devices, and the greater the dif­fer­ence in the lev­els of their loca­tion, the bet­ter the cir­cu­la­tion of the coolant.

The advan­tages of the grav­i­ta­tion­al sys­tem, in addi­tion to ener­gy inde­pen­dence, include its self-reg­u­la­tion. With more inten­sive cool­ing of the coolant in one of the radi­a­tors, the local flow of the coolant accel­er­ates, and heat begins to be inten­sive­ly sup­plied to the cooled radi­a­tor.

4 Rules for a Good Gravity Heating System

  1. The diam­e­ter of the inlet and out­let coolant pipelines should be as large as pos­si­ble. In prac­tice, met­al pipes with a diam­e­ter of one to one and a half inch­es or sim­i­lar plas­tic (or met­al-plas­tic) pipes are used.
  2. High­ways are laid with the least num­ber of turns.
  3. The instal­la­tion of shut-off valves is not rec­om­mend­ed; in extreme cas­es, spe­cial ball valves with the low­est hydraulic resis­tance are used.
  4. It is rec­om­mend­ed to use water as a heat car­ri­er, as it has the low­est vis­cos­i­ty.

Structural diagram of the gravitational heating system

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