The principle of operation and installation rules of the bypass valve


The bypass valve is includ­ed in the pack­age of ele­ments of the res­i­den­tial heat­ing sys­tem. The bypass jumper pro­vides con­tin­u­ous water sup­ply where a com­plete shut­down of the pump­ing sta­tion is impos­si­ble (for exam­ple, in a cool­ing sta­tion). Let’s take a clos­er look at what it is.

What is a bypass valve

Bypass place­ment

Bypass — a mech­a­nism that con­nects the nodes of the heat­ing sys­tem in the for­ward and reverse direc­tion and its bypass part.

In hydraulics, the part serves to facil­i­tate repair and clean­ing work in case of fail­ure of heat­ing struc­tures, increas­es the safe­ty of heat sup­ply and the per­for­mance of pipe (shut­off) valves.

Technical specifications

The tech­ni­cal char­ac­ter­is­tics of bypass units are indi­cat­ed by alpha­bet­ic char­ac­ters and are reg­u­lat­ed by GOST (No. 26349–84; 28338–89). Marks are decod­ed as fol­lows:

  1. “DN” is the typ­i­cal size of the hole in the stub pipes. The diam­e­ter of the con­nect­ing tube may vary slight­ly (small­er or larg­er). GOST reg­u­lates the nom­i­nal vol­ume of the branch pipe with the let­ter des­ig­na­tion — “Du” (con­di­tion­al pas­sages).
  2. “KVS” is the bypass capac­i­ty expressed as a ratio. The mark­ing cor­re­sponds to the flow rate of a liq­uid with a tem­per­a­ture of 20 ° C pass­ing through the hydraulic device per hour and a vol­ume equal to 1 meter in a cube. The pres­sure loss of the valve must not exceed 1 bar. This val­ue is used to cal­cu­late the water head loss.
  3. “PN” — indi­cates the nom­i­nal and max­i­mum pres­sure of the bypass, at a medi­um tem­per­a­ture of 20°C. The indi­ca­tor indi­cates the ratio of tem­per­a­ture and pres­sure for safe and long-term oper­a­tion of heat­ing equip­ment. In the guest, the des­ig­na­tion “PN” (nom­i­nal pres­sure) is “Ru” (con­di­tion­al pres­sure).
  4. “Set­ting range” — the pres­sure dif­fer­ence main­tained by the force of the set­point (spring) installed in the bypass valve — by the man­u­fac­tur­er.

Principle of operation

The prin­ci­ple of oper­a­tion of the bypass valve

The prin­ci­ple of oper­a­tion of the bypass valve in the gate struc­ture is based on the oppo­si­tion of the pres­sure of the spring and water. A com­pressed spring press­es on the valve on one side, and the work­ing medi­um with a large force on the oth­er. The pres­sures of the com­bined com­po­nents of the struc­ture hold the bypass in the closed posi­tion. As soon as one of the poten­tials exceeds the allow­able pres­sure (1.5 ‑2 times), it opens com­plete­ly.

The degree of open­ing of the shut­ter depends on the force of the work­ing medi­um press­ing on the valve. The damper gen­er­ates the set pres­sure by means of a spring. The com­pres­sion lev­el affects the pres­sure drop of the sys­tem.

For ref­er­ence! Bypass valves have a low accu­ra­cy of main­tain­ing pres­sure in heat­ing appli­ances.

Scope and purpose of use

Bypass valve options


In the event of a pow­er out­age, the need for a bypass for the cir­cu­la­tion pump (its instal­la­tion) ensures con­ti­nu­ity of oper­a­tion and elim­i­nates emer­gency oper­a­tion.

In pipeline struc­tures, the shut-off valve is designed for back­up removal of incom­ing liq­uid to a sep­a­rate line (spare). In the event of prob­lems asso­ci­at­ed with water pres­sure in the pipes, the bypass damper clos­es access to the heat­ing radi­a­tor, direct­ing water in the oppo­site direc­tion or to a sep­a­rate chan­nel.

Types of bypass valves

Bypass types

Gate valves fall into two main cat­e­gories:

  1. Bypass with­out valve (direct act­ing). The coolant with this type of shut­ter cir­cu­lates through the pipes.
  2. Bypass includ­ing reverse direc­tion valve. This type of jumper is used for indi­vid­ual and com­mon pump­ing sta­tions for sup­ply­ing water to res­i­den­tial premis­es. Works when turned on (in open mode) and off (in closed mode).

Differences and scope of use

Both cat­e­gories of bypass valves are divid­ed into sub­species:

  1. Bypass valve in auto­mat­ed oper­a­tion. It is mount­ed on the pip­ing of the grav­i­ty and pump heat­ing sys­tem. Dur­ing nor­mal oper­a­tion of the elec­tron­ic blow­er, the auto­mat­ic bypass is closed, and when stopped, it is open.

Auto­mat­ic bypass­es are also divid­ed into types: injec­tion type and valve type.

In the first case, the bypass oper­ates on the prin­ci­ple of a hydraulic ele­va­tor, cap­tur­ing the dis­charged area of ​​the coolant, direct­ing it into the gen­er­al flow and cre­at­ing the nec­es­sary pres­sure. The valve works offline even when the elec­tri­cal net­work is turned off.

In the sec­ond case, a reverse direc­tion valve is mount­ed in the bypass, which pre­vents the reverse flow of the liq­uid in the pipeline. In the right direc­tion, water flows with­out obsta­cles through the heat­ing pipes and pipes.

  1. Bypass with­out addi­tion­al equip­ment. This heat­ing sys­tem is a con­ven­tion­al pipe, not equipped with addi­tion­al devices. Used when installing heat­ing radi­a­tors. The liq­uid in such a pipe pass­es freely with­out obsta­cles in an uncon­trolled man­ner.
  2. Shut­ter valve for man­u­al mech­a­nism. Bypass is a valve with a ball mech­a­nism. The device does not cre­ate obsta­cles to the gen­er­al flow of the ener­gy car­ri­er in the open state, and also does not reduce the clear­ance of the pipeline open­ings. When the faucet is com­plete­ly closed, water will not enter the noz­zles. The method makes it pos­si­ble to reg­u­late the heat­ing of the room.

In indi­vid­ual space heat­ing sys­tems, a bypass valve is required for the fol­low­ing work:

  • pump­ing sta­tion pip­ing;
  • for sup­ply­ing a small vol­ume of liq­uid to the boil­er room;
  • instal­la­tion of heat­ing radi­a­tors in a sin­gle-pipe line;
  • uni­form heat­ing of under­floor heat­ing.

Each bypass con­nec­tion has its own char­ac­ter­is­tics, depend­ing on the place of oper­a­tion.

Bypass valve installation steps (for radiators and with a circulation pump)

Do-it-your­self bypass valve instal­la­tion


Installing a bypass in a heat­ing sys­tem equipped with a cir­cu­la­tion pump is car­ried out as fol­lows:

  • excess liq­uid is drained from a com­mon pipe;
  • a sec­tion of pipe, 40 cm in size, is dis­man­tled from the coolant;
  • holes of the required diam­e­ter are cut at the ends of the pipe for join­ing the bypass;
  • a fil­ter is installed on the cropped areas;
  • then the bypass valve is mount­ed;
  • hydraulic pump crash­es.

Impor­tant! Instal­la­tion of screws for dis­tri­b­u­tion of incom­ing water is car­ried out in the direc­tion of the total flow of the pipeline.

Installing a bypass in a heat­ing sys­tem

For heat­ing bat­ter­ies, the fol­low­ing instal­la­tion scheme applies:

  • the diam­e­ters of the bypass and main pipes are checked;
  • at the dock­ing ends are mount­ed: jumpers of a sin­gle-pipe cir­cuit and a con­trol valve;
  • then the valve is installed as close as pos­si­ble to the heat­ing radi­a­tor.

Impor­tant! Before insert­ing the bypass, the pipe must be checked for the pres­ence of an air lock.

Required tool

You can install the bypass line with your own hands using the instal­la­tion tools, the list of which con­sists of the fol­low­ing items:

  • tape mea­sure for mea­sur­ing the length and vol­ume of the pipe;
  • lev­el for adjust­ing heat­ing appli­ances and the slope of the water sup­ply;
  • pli­ers for remov­ing and main­tain­ing indi­vid­ual parts of the heat­ing sys­tem;
  • wrench­es for join­ing the struc­ture;
  • a set of keys for instal­la­tion (reg­u­lar);
  • met­al cut­ter;
  • screw­drivers: cross-shaped and flat;
  • pipe cut­ter (for pipes of large diam­e­ter);
  • weld­ing machine;
  • grinder for lev­el­ing the cor­ners of pipes and pipes;
  • per­fo­ra­tor;
  • gas burn­er.

For one-time work, it is not nec­es­sary to pur­chase all the tools, but you can rent them.


Recommendations and typical mistakes

The insert of the bypass valve should be made accord­ing to the rules of SNIP and the rec­om­men­da­tions below:

  1. Before instal­la­tion, it is desir­able to put fil­ters (mesh type).
  2. Mount­ing monomers will help con­trol water pres­sure.
  3. Do not twist, squeeze or stretch the noz­zles dur­ing instal­la­tion.
  4. The aver­age size of the pipe joint should not exceed 5 DN before and 10 DN after the bypass.

The bypass valve can be mount­ed on hor­i­zon­tal­ly and ver­ti­cal­ly direct­ed pipe sec­tions, in accor­dance with the instal­la­tion instruc­tions.

Advantages of using a valve in a heating system

Loca­tion of the bypass in the heat­ing sys­tem

The bypass valve insert has the fol­low­ing advan­tages:

  • reduces the lev­el of rust;
  • reg­u­lates the heat­ing tem­per­a­ture;
  • pre­vents noise of unnat­ur­al ori­gin;
  • reduces the load on the hydraulic pump.

The fol­low­ing errors when installing the bypass valve can lead to a com­plete replace­ment of pipes in the room:

  • instal­la­tion of a pump with a wet rotor;
  • incor­rect loca­tion of the valve;

For ref­er­ence! If you do not elim­i­nate smudges near the man­u­al tap, the pipe may bend.

Energy saving

Installing a sim­ple engi­neer­ing solu­tion, like a bypass valve, will save ener­gy costs, as the heat trans­fer of the heat­ing radi­a­tor increas­es by 10%. At the same time, the vol­ume of the coolant, with the bypass valve includ­ed in the pack­age, will increase up to 30%.


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