How to choose a pipe for a geyser?


One of the most com­mon devices that can pro­vide unin­ter­rupt­ed hot water at home is a gas water heater. It per­fect­ly copes with heat­ing of any vol­ume of water in the short­est pos­si­ble time. At the same time, mod­ern mod­i­fi­ca­tions allow you to clear­ly set the required tem­per­a­ture and auto­mat­i­cal­ly turn on and off in accor­dance with the oper­at­ing mode of the draw-off point.

Instan­ta­neous gas-fired water heaters are quite eco­nom­i­cal and safe to oper­ate. The only incon­ve­nience is the need to orga­nize a high-qual­i­ty removal of com­bus­tion prod­ucts. Once and for all, this prob­lem can be solved only with the help of a com­pe­tent instal­la­tion of an exhaust pipe for a gas col­umn. When choos­ing the para­me­ters and con­fig­u­ra­tion of the flue sys­tem, you must fol­low the man­u­fac­tur­er’s instruc­tions and cur­rent reg­u­la­tions.

Regulatory Requirements

Accord­ing to the table of def­i­n­i­tions NPB 252–98, the exhaust pipe for the gas col­umn is the con­nect­ing pipe for the smoke out­let of the appa­ra­tus and the smoke chan­nel. Accord­ing­ly, it trans­ports the prod­ucts of gas com­bus­tion and must meet the require­ments for chim­neys. Fail­ure to com­ply with them is fraught with gas con­t­a­m­i­na­tion of the room and car­bon monox­ide poi­son­ing.

All require­ments for chim­neys are set out in the fol­low­ing reg­u­la­to­ry doc­u­ments:

  • NPB 252–98;
  • Rules for the pro­duc­tion of pipe and fur­nace work VDPO;
  • SP 42–101-2003, Appen­dix G
  • SP 60.13330.2012, which is an updat­ed ver­sion of SNiP 41–01-2003 (replac­ing SNiP 2.04.05–91).

The main pro­vi­sions that direct­ly relate to smoke removal from domes­tic gas water heaters are as fol­lows:

  • The cross-sec­tion­al area of ​​the exhaust pipe is tak­en not less than the cross-sec­tion of the out­let pipe of the unit;
  • It is nec­es­sary to ensure the com­plete tight­ness of the chim­ney, its resis­tance to cor­ro­sion and high tem­per­a­tures up to 200 ° C;
  • The lay­ing of con­nect­ing pipes through liv­ing rooms is pro­hib­it­ed;
  • The ver­ti­cal sec­tion of the exhaust pipe at the out­let of the col­umn must be at least 500 mm high, in some cas­es it can be reduced to 250 mm;
  • Con­nect­ing pipes should be up to 3 m long in new build­ings and up to 6 m in exist­ing ones;
  • It is allowed to use no more than 3 turns with a bend­ing radius not less than the diam­e­ter;
  • The exhaust pipe is installed at a dis­tance of at least 5 cm from the ceil­ing or wall of non-com­bustible mate­ri­als, if they are com­bustible or slow-burn­ing, then at least 25 cm. The dis­tance can be reduced to 10 cm by tak­ing pro­tec­tive mea­sures in accor­dance with SP 42–101-2003;
  • If the con­nect­ing pipe for the geyser pass­es through an unheat­ed room, then ther­mal insu­la­tion must be used;
  • The chim­ney must be laid with a slope of 0.01 or more towards the appli­ance.


Impor­tant! Removal of com­bus­tion prod­ucts is pos­si­ble only through smoke ducts or spe­cial­ly installed chim­neys; the use of ven­ti­la­tion ducts is strict­ly pro­hib­it­ed.

Smoke chan­nels are arranged in walls made of non-com­bustible mate­ri­als and insu­lat­ed if nec­es­sary to pre­vent con­den­sa­tion. If there are no suit­able walls or if there are no chan­nels for remov­ing com­bus­tion prod­ucts in the build­ing in use, then a wall-mount­ed or root-type chim­ney is installed.

Each fuel-burn­ing device must have a sep­a­rate smoke chan­nel or pipe. In some cas­es, it is allowed to remove exhaust gas­es from the col­umn and the boil­er into one chim­ney with an increase in the pipe sec­tion. In this case, the intro­duc­tion of com­bus­tion prod­ucts into the chan­nel should be car­ried out at dif­fer­ent lev­els at a dis­tance of at least 0.75 m or at the same lev­el using a cut with a height of 0.75 m and a thick­ness of 0.12 m.

The chim­ney must be strict­ly ver­ti­cal and have a remov­able sock­et at the base or a pock­et 250 mm deep with a door for clean­ing soot. If it is nec­es­sary to bypass exist­ing obsta­cles, a devi­a­tion of up to 30 ° from the ver­ti­cal is allowed, while the cross-sec­tion­al area is pre­served, and the off­set should not exceed 1 m.

On a note: the round or rec­tan­gu­lar open­ing under the flue inlet is intend­ed for soot clean­ing and must always be acces­si­ble for main­te­nance. When doing a gen­er­al clean­ing in the kitchen, do not for­get to open the door and clean out the soot, leaves and oth­er debris.

The height of the chim­ney is a key fac­tor in cre­at­ing good draft. It is she who is deci­sive in the issue of high-qual­i­ty removal of com­bus­tion prod­ucts. The height of the chim­ney must be deter­mined in accor­dance with the scheme giv­en in SP 42–101-2003 (Appen­dix D).

If there are taller build­ings or trees in the vicin­i­ty, the height of the wind dam zone must be addi­tion­al­ly checked and, if nec­es­sary, the height of the chim­ney must be increased. In any case, the ele­va­tion above the adja­cent part of the roof must be at least 50 cm, and with a com­bined (flat) roof — at least 200 cm.

After the instal­la­tion is com­plet­ed, the tight­ness of the flue pipe and the pres­ence of draft must be checked. In order to avoid the dan­ger of draft dis­ap­pear­ance as a result of freez­ing of the head or its over­lap­ping with for­eign objects, it is for­bid­den to use noz­zles on chim­neys in the form of umbrel­las, deflec­tors, etc.

On a note: in rooms with her­met­i­cal­ly sealed win­dows, the geyser may peri­od­i­cal­ly turn off due to insuf­fi­cient air flow. Automa­tion stops the oper­a­tion of the water heater to pre­vent back draft, which may occur due to rar­efac­tion of the air in the room. To fix the prob­lem, it is enough to keep the kitchen win­dow in micro-ven­ti­la­tion mode while the col­umn is run­ning.

Selection of pipeline material

When going to buy an exhaust pipe, you need to care­ful­ly study the instal­la­tion con­di­tions, know the mod­el of the geyser, the diam­e­ter of the smoke exhaust pipe and the required lengths of the pipeline sec­tions. It is advis­able to stock up on the lay­out of the water heater indi­cat­ing all dis­tances, this will help you bet­ter nav­i­gate when choos­ing the nec­es­sary ele­ments and, if nec­es­sary, get expert advice.

Accord­ing to SP 60.13330.2012, con­nect­ing and chim­ney pipes must be made of non-com­bustible mate­ri­als with an equiv­a­lent inner sur­face rough­ness of not more than 1.0 mm. In addi­tion, they must be tight with tight­ness class B and pre­vent air leaks at the joints and at the junc­tion with the smoke chan­nel. The use of mate­ri­als such as ceram­ics and stain­less steel is rec­om­mend­ed.

SP 42–101-2003 allows the use of roof­ing or gal­va­nized steel with a thick­ness of 1 mm or more, flex­i­ble met­al cor­ru­gat­ed pipes and uni­fied ele­ments sup­plied with the unit.

It is very impor­tant that the mate­r­i­al of the chim­ney is resis­tant to cor­ro­sion, as con­den­sate can quick­ly destroy it. The smoother the inner sur­face, the less soot will col­lect on it. The rough­ness of the out­er sur­face is not stan­dard­ized, but from the point of view of ease of clean­ing, a smoother mate­r­i­al for the con­nect­ing pipe will be more prac­ti­cal.

How­ev­er, cor­ru­gat­ed pipes are quite pop­u­lar for con­nect­ing a geyser to a smoke chan­nel. They are easy to work with and very com­fort­able in tight spaces. Their use allows you to suc­cess­ful­ly avoid obsta­cles and car­ry out con­cealed instal­la­tion, hid­ing equip­ment in cab­i­nets and clos­ing the pipeline with remov­able pan­els.

The main dis­ad­van­tage of cor­ru­gat­ed pipes is the pos­si­bil­i­ty of burnout under the influ­ence of high tem­per­a­tures. There­fore, for fire safe­ty pur­pos­es, it is rec­om­mend­ed to use stain­less steel cor­ru­ga­tion, and not cheap­er alu­minum.

Gal­va­nized steel with a thick­ness of 1 mm is a per­fect­ly accept­able mate­r­i­al, but there is an opin­ion that when heat­ed strong­ly, gal­va­niz­ing can release harm­ful sub­stances. Accord­ing­ly, its use is unde­sir­able for mod­els with high flue gas tem­per­a­tures.

Exhaust pipes made of steel coat­ed with heat-resis­tant enam­el have proven them­selves quite well. White shiny pipes look quite nice in the kitchen and can fit into almost any inte­ri­or.

The ide­al mate­r­i­al in terms of dura­bil­i­ty, aes­thet­ics and com­pli­ance with all require­ments is stain­less steel. It is not threat­ened by cor­ro­sion, burnout, dust accu­mu­la­tion, or acci­den­tal dam­age. Quite nat­u­ral­ly, it turns out to be the most expen­sive.

Mounting order

Instal­la­tion of an exhaust pipe for a geyser from any mate­r­i­al begins with tak­ing mea­sure­ments and prepar­ing all the nec­es­sary ele­ments. In the case of cor­ru­ga­tion, the pro­ce­dure for car­ry­ing out the work is very sim­ple. It is enough to take the pipeline of the required length, put it on the flue pipe of the water heater and clamp it with a clamp. The free end is insert­ed into the dec­o­ra­tive ring and fixed in the open­ing of the smoke chan­nel. The main thing here is to match the diam­e­ter of the cor­ru­gat­ed pipe with the size of the out­let of the col­umn.

For all oth­er mate­ri­als, it is nec­es­sary to pre­pare the required num­ber of straight and rotary ele­ments that will be insert­ed into each oth­er, form­ing the desired chim­ney con­fig­u­ra­tion accord­ing to the design­er’s prin­ci­ple. Rota­tion angles are stan­dard or cus­tom-made for spe­cif­ic dimen­sions.

When assem­bling, ensure the max­i­mum tight­ness of the con­nec­tions. The entry of one ele­ment into anoth­er must be at least half the diam­e­ter. For bet­ter seal­ing, a heat-resis­tant sealant is used. The joints are fas­tened with clamps and are locat­ed out­side the ceil­ings in free access.

When fix­ing the exhaust pipe for the gas col­umn, it is nec­es­sary to exclude the pos­si­bil­i­ty of deflec­tion, as well as con­tact with elec­tri­cal wiring, gas pipes and oth­er com­mu­ni­ca­tions. To pass through the floors and roofs, it is nec­es­sary to use addi­tion­al ther­mal insu­la­tion or a spe­cial unit — cut­ting.

Due to the lim­i­ta­tion on the num­ber of allowed turns, the num­ber of pos­si­ble chim­ney con­fig­u­ra­tions is rather lim­it­ed. In total, there are three main options, depend­ing on the loca­tion of the exhaust open­ing. Two more can be obtained by mir­ror­ing the pre­vi­ous ones.

All the require­ments and rec­om­men­da­tions set out above apply to devices with an open com­bus­tion cham­ber. The norms also allow the removal of com­bus­tion prod­ucts through an out­er wall with­out a ver­ti­cal smoke chan­nel from gas water heaters with a closed com­bus­tion cham­ber and forced exhaust gas­es. In this case, instal­la­tion is car­ried out accord­ing to the man­u­fac­tur­er’s instruc­tions in com­pli­ance with the stan­dard dis­tances and lengths of the coax­i­al chim­ney spec­i­fied in SP 42–101-2003.


Thus, the instal­la­tion of an exhaust pipe for a geyser has many impor­tant nuances. Giv­en the great dan­ger that can arise from non-com­pli­ance or par­tial vio­la­tion of reg­u­la­to­ry require­ments, it is nec­es­sary to approach this issue with the utmost seri­ous­ness and, if pos­si­ble, entrust the exe­cu­tion of all work to pro­fes­sion­als.

High-qual­i­ty instal­la­tion of the con­nect­ing pipe is the key to the safe oper­a­tion of the geyser. Strict obser­vance of all the require­ments of reg­u­la­to­ry doc­u­ments will ensure the sta­bil­i­ty of the device and allow the own­ers to use a con­ve­nient water heater with­out fear of car­bon monox­ide poi­son­ing.


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