How to properly drain the heating system?

Faced with repair work, going on a long trip or becom­ing a vic­tim of an acci­dent, many are won­der­ing if it is nec­es­sary to drain the water from the heat­ing sys­tem? In most cas­es, the answer is yes, although there are sit­u­a­tions where you can fix the prob­lem or make repairs with radi­a­tors filled with liq­uid.

Although the drain pro­ce­dure is not par­tic­u­lar­ly com­pli­cat­ed, com­pli­ance with the oper­at­ing rules is an impor­tant nuance. If you vio­late the pro­ce­dure, you can flood the floors in your own house with water. And if the drain is car­ried out in a mul­ti-storey build­ing, then neigh­bors may also suf­fer from incor­rect actions.

Why is it necessary to drain water from heating systems?

When should water be drained?

Drain­ing the heat­ing sys­tem is nec­es­sary in the fol­low­ing cas­es:

  • when it is nec­es­sary to elim­i­nate leaks in pipes;
  • if old radi­a­tors are replaced with more mod­ern mod­els;
  • when pre­ven­tive mea­sures are tak­en to clean the sys­tem from accu­mu­lat­ed con­t­a­m­i­nants;
  • if you need to replace the coolant.

With filled cav­i­ties of bat­ter­ies and pipes, these works can­not be per­formed. Water is drained in the event of an emer­gency or at the moment when the own­ers of the dwellings intend to leave the premis­es for a long time.

Features of the design of the drain of the heating system

The heat­ing sys­tem of an apart­ment build­ing and a pri­vate house has sig­nif­i­cant dif­fer­ences. Heat­ing in cot­tages occurs through an autonomous sys­tem, which includes a boil­er, pipelines, valves and direct­ly radi­a­tors, and some­times an installed sys­tem of under­floor heat­ing.

In mul­ti-storey build­ings, the main struc­tur­al ele­ments are the sup­ply and return ris­ers, the inter­nal pip­ing sys­tem, shut-off valves, drain cocks and the bat­ter­ies them­selves. In this regard, the dis­charge of water from the heat­ing sys­tem will be some­what dif­fer­ent for both sys­tems, although the prin­ci­ple of oper­a­tion is the same.

How to properly drain the heating system?

Hav­ing dealt with the main ele­ments of the heat­ing struc­ture, you can begin to emp­ty it. How to prop­er­ly drain the heat­ing sys­tem in pri­vate and apart­ment build­ings?How to properly drain the heating system

Drainage in a private house

For the drain pro­ce­dure, the own­er of the cot­tage will have to pre­pare a hose in advance, through which the liq­uid released from the sys­tem will flow. One end of the hose is con­nect­ed to the boil­er tap, the oth­er is sent to the most con­ve­nient place for the own­er of the house, where it is pos­si­ble to emp­ty the struc­ture with­out dam­age (on the ground of a per­son­al plot, sew­er­age).

The sequence of actions for drain­ing water:

  1. The boil­er is turned off, its work stops.
  2. A hose is put on the boil­er return valve (usu­al­ly the out­let pipe is locat­ed on the right side under the boil­er), so emp­ty­ing is faster. If the crane is not under the struc­ture, refer to the autonomous sys­tem dia­gram and find out its loca­tion. The reverse part of the hose is sent to the sew­er drain, front gar­den or reg­u­lar buck­et.
  3. Open the valve and wait until the liq­uid stops flow­ing (the pres­sure in the sys­tem decreas­es dur­ing this peri­od), the valve is closed back.
  4. After drain­ing, you need to take care of the access of air to the cav­i­ty of the struc­ture. To do this, it is nec­es­sary to open the so-called Mayevsky crane, which is usu­al­ly locat­ed at the high­est point of the autonomous sys­tem. For exam­ple, on a heat­ed tow­el rail or one of the radi­a­tors (if the cot­tage is two-sto­ry, then Mayevsky’s tap will be on the bat­tery of the 2nd floor).
  5. The air will begin to push out the remain­ing water from the bat­ter­ies and the boil­er, so the drain must be car­ried out again.
  6. Now, when there is prac­ti­cal­ly no liq­uid left in the sys­tem, its insignif­i­cant rem­nants are “blown out” by open­ing all the Mayevsky taps in the struc­ture, and the next drain of water is car­ried out.
  7. Now the end of the hose attached to the return pipe is removed from it and attached to the sup­ply valve.
  8. The final drain­ing of the liq­uid from the heat­ing sys­tem is car­ried out. To achieve max­i­mum emp­ty­ing, it is nec­es­sary to install the hose as low as pos­si­ble in rela­tion to the out­let cocks.How to drain the heating system in the apartment

How­ev­er, if the own­er of a pri­vate house has an under­floor heat­ing sys­tem, then the above scheme will not help him. To dump liq­uid from it, you will need to use a spe­cial com­pres­sor.

Drainage in an apartment building

Drain­ing the heat­ing sys­tem in a mul­ti-storey build­ing is more dif­fi­cult in part because it is nec­es­sary to obtain per­mis­sion from the local man­age­ment com­pa­ny to drain the ris­er. This ser­vice is paid, and the date will be set not by the own­er of the apart­ment, but by the employ­ees of the hous­ing and com­mu­nal ser­vices, which may cause some incon­ve­nience.

It is bet­ter to plan work on repair­ing the heat­ing sys­tem at the end of spring — sum­mer — begin­ning of autumn, since dur­ing the heat­ing peri­od it is pos­si­ble to drain the liq­uid only for a few hours and for a high fee.

How­ev­er, it is pos­si­ble to replace the bat­tery or car­ry out minor repairs with­out emp­ty­ing the entire heat­ing struc­ture. Most radi­a­tors are equipped with valves, with which you can block the flow of coolant to a local area.


  1. The valve is closed to shut off the water sup­ply to the radi­a­tors.
  2. Using an adjustable wrench, the plug is removed or, if avail­able, the out­let cock is opened. The liq­uid is drained into a basin or buck­et.
  3. If there are no out­lets, you will have to dis­con­nect the bat­tery com­plete­ly and get rid of the coolant through the top.

If a more seri­ous repair is required than a reg­u­lar radi­a­tor change, then you need to drain the ris­er. This pro­ce­dure is per­formed by the employ­ees of the man­age­ment com­pa­ny as fol­lows:

  1. The valve in the attic or ceil­ing of the upper floor is closed.
  2. Close the valve in the base­ment or base­ment.
  3. The plug is removed or drain valves are opened, the coolant is dis­charged from the sys­tem.

As you can see, the pro­ce­dure for get­ting rid of the coolant from the sys­tem has sig­nif­i­cant dif­fer­ences for hous­es of dif­fer­ent types.


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