Diameter of polypropylene pipes for heating: summary table


The ease of instal­la­tion and high per­for­mance of polypropy­lene pipelines in water sup­ply and heat­ing sys­tems is only the tip of the ice­berg. For the cor­rect oper­a­tion of the installed com­mu­ni­ca­tions, it is not enough to choose the type of poly­mer pipe and buy the mate­r­i­al in the right amount — pre­lim­i­nary design sketch­es are nec­es­sary, and for large objects — seri­ous ther­mal and hydraulic cal­cu­la­tions. For the heat­ing sys­tem to be effec­tive, polypropy­lene pipes for heat­ing must have a diam­e­ter con­firmed by these cal­cu­la­tions.

Let us con­sid­er in more detail the sig­nif­i­cance of the diam­e­ter of polypropy­lene pipes in the con­struc­tion of pipelines.

Pipe material for communications. What are the parameters of the pipe

The ques­tions of how the water sup­ply should look like, what diam­e­ter of the pipes should be in the main sup­ply­ing heat to heat­ing radi­a­tors, are solved at the design stage of life sup­port sys­tems in the house. As a result, the diam­e­ter of polypropy­lene pipes for water sup­ply can often dif­fer from the iden­ti­cal size of the pipeline of the heat­ing sys­tem, since these com­mu­ni­ca­tions have dif­fer­ent pur­pos­es and are there­fore exposed to dif­fer­ent fac­tors.

The capac­i­ty of heat net­works, rec­om­mend­ed by pro­fes­sion­al experts, should ensure the speed of the coolant at least 0.4–0.6 m / s — this deter­mines the amount of ther­mal ener­gy sup­plied to heat res­i­den­tial premis­es.

On a note: if the boil­er water sup­ply rate in the pipeline of the heat­ing sys­tem is less than 0.2 m / s, then there is a high prob­a­bil­i­ty of air­ing the line, and exceed­ing the sup­ply rate by 0.2 m / s will lead to an increase in costs — the costs of equip­ment sub­ject­ed to heavy loads will increase.

The use of polypropy­lene prod­ucts has great­ly sim­pli­fied the work on equip­ping res­i­den­tial facil­i­ties with water heat­ing and water sup­ply sys­tems. How­ev­er, you need to know exact­ly which type of poly­mer pipe mate­r­i­al is suit­able in a par­tic­u­lar case. The types of polypropy­lene pipes that exist today have dif­fer­ent tech­ni­cal char­ac­ter­is­tics and are designed for a spe­cif­ic area of ​​u200bu200buse.

The most reli­able for the instal­la­tion of water heat­ing pipelines and hot water sup­ply sys­tems (DHW) are prod­ucts of the PN25 or PN30 brand. It is these brands that are able to with­stand pres­sures up to 25 and 30 atm. respec­tive­ly at the oper­at­ing tem­per­a­ture of the coolant 950C. Even short-term oper­a­tion of such pipes is allowed at a water tem­per­a­ture of 1200C, as a dis­tinc­tive fea­ture of these prod­ucts are thick walls.

Sam­ples of polypropy­lene pipes rein­forced with alu­minum.


The main arti­cle about polypropy­lene pipes.

For cold water sup­ply, polypropy­lene pipes with a homo­ge­neous wall are used. For hot water sys­tems and heat­ing cir­cuits, rein­forced prod­ucts are used, since the inclu­sion of an alu­minum or fiber­glass shell in the wall struc­ture of a polypropy­lene pipe sig­nif­i­cant­ly increas­es the strength of the pipe mate­r­i­al and reduces the amount of ther­mal expan­sion.

For ref­er­ence: in rein­forced pipelines, ther­mal expan­sion is 0.03 mm / m0C, while for chan­nels with a wall of homo­ge­neous polypropy­lene this val­ue is about 0.15 mm / m0C. Based on this, homo­ge­neous prod­ucts are suit­able for cold water sup­ply, and only rein­forced polypropy­lene is used for heat­ing and hot water sys­tems.

What diameters are produced polypropylene pipe materials

When choos­ing com­po­nents for a heat­ing and water sup­ply sys­tem, the deci­sive fac­tors are the tem­per­a­ture of the liq­uid, its flow rate and pres­sure. The required cross-sec­tion­al area of ​​​​the water sup­ply sys­tem is deter­mined in this case by cal­cu­la­tions made in accor­dance with the scope and oper­at­ing con­di­tions of the equip­ment.

Based on the con­fig­u­ra­tion of the pipe sec­tion (round ring), its geo­met­ric para­me­ters are deter­mined by the out­er and inner diam­e­ters. The cur­rent clas­si­fi­ca­tion of polypropy­lene pipes clear­ly defines the typ­i­cal dimen­sions of each type of pipe prod­ucts used for instal­la­tion.

To date, both domes­tic and for­eign man­u­fac­tur­ers pro­duce com­po­nents for pipelines in a stan­dard ver­sion. Tak­ing into account prac­ti­cal appli­ca­tion, stan­dard engi­neer­ing solu­tions have been devel­oped that allow deter­min­ing the opti­mal pas­sage in prod­ucts for home heat­ing and oth­er water com­mu­ni­ca­tions. Based on the data in the table, it is pos­si­ble to make the right choice of equip­ment and com­po­nents for the heat main with­out resort­ing to hydraulic cal­cu­la­tions.

On a note: the val­ues ​​indi­cat­ed in the mark­ing on the prod­ucts should not be con­sid­ered as the para­me­ter of the inter­nal sec­tion. On polypropy­lene mate­ri­als, the out­er diam­e­ter is usu­al­ly indi­cat­ed.

As a rule, one of the fol­low­ing out­er diam­e­ter val­ues ​​is present in the mark­ing:

16, 20.25, 32 and 40mm,

which cor­re­spond to the inner diam­e­ters of PN25 polypropy­lene pipes:

10.6; 13.2; 16.6; 21.2; 26.6 mm.

For ease of use, the cor­re­spon­dence between the diam­e­ters and wall thick­ness­es of polypropy­lene pipes used in heat­ing and water sup­ply sys­tems is sum­ma­rized in the table:

Table with data on the diam­e­ters and wall thick­ness of polypropy­lene pipes used in every­day life series


Rea­son­able ques­tion. Why are exter­nal para­me­ters applied to fin­ished prod­ucts, if the size of the inter­nal pas­sage of the pipeline is so impor­tant for func­tion­al­i­ty. The thing is that the out­er diam­e­ter indi­cates the appro­pri­ate type of con­nec­tion.

The poten­tial of using polypropy­lene pipes of var­i­ous out­er diam­e­ters at a coolant veloc­i­ty in the pipeline of 0.7 m/s:

  • a pipe with a diam­e­ter of 16 mm is designed to con­nect one or two heat­ing radi­a­tors;
  • a val­ue of 20 mm cor­re­sponds to the con­nec­tion of up to 5 radi­a­tors with a total pow­er of up to 7000 watts);
  • for a larg­er num­ber of radi­a­tors (with a total pow­er of up to 11 kW), propy­lene poly­mer pipes with an out­er diam­e­ter of 25 mm are used;
  • polypropy­lene pipe mate­r­i­al with an out­er dimen­sion of 32 mm is designed to equip the house as a whole or one floor with a heat­ing sys­tem of 10–12 kW of total pow­er (max­i­mum 19 kW);
  • prod­ucts with a diam­e­ter of 40 mm are used for lay­ing main pipelines in res­i­den­tial facil­i­ties of a large area. Usu­al­ly these are cot­tages and coun­try hous­es, in which the num­ber of heaters reach­es 20 pieces, and the total pow­er of all con­nec­tion points is approx­i­mate­ly 30 kilo­watts.

Influence of pipe diameter on the performance of the heating system

The coolant sup­ply rate and the amount of trans­ferred ther­mal ener­gy direct­ly depend on the inter­nal sec­tion of polypropy­lene pipelines. For clar­i­ty of this state­ment, the depen­dence of pro­vid­ing ther­mal ener­gy on the inten­si­ty of the coolant sup­ply and the val­ues ​​of the pipeline diam­e­ters is sum­ma­rized in the table:

Selec­tion table for polypropy­lene pipe mate­r­i­al depend­ing on the inten­si­ty of the coolant sup­ply and the need for ther­mal ener­gy


The ther­mal pow­er is indi­cat­ed in W, the inten­si­ty of the coolant sup­ply in kg / s. The cal­cu­lat­ed data are based on aver­age tem­per­a­tures: of the sup­plied coolant at 800C, return to 600C, room air +200FROM..

For exam­ple: at a flow rate of 0.4 m/s, the fol­low­ing amount of heat ener­gy will be trans­ferred in the pipeline:

  • for a line with an out­er size of 20 (inter­nal sec­tion 13.2 mm), the amount of heat is 4.1 kW;
  • for propy­lene prod­ucts Ø 25 and 16.6, respec­tive­ly, the amount of heat will be 6.3 kW;
  • propy­lene pipelines with out­er and inner diam­e­ters of 32 and 21.2, respec­tive­ly, have a ther­mal ener­gy sup­ply of 11.5 kW;
  • pipe mate­ri­als of 40 mil­lime­ters (inter­nal clear­ance size 26.6 mm) will pro­vide heat sup­ply in the amount of 17 kW.

With an increase in the flu­id flow rate to 0.7 m/s, the inten­si­ty of the coolant sup­ply will imme­di­ate­ly increase by 70–80%.

Impor­tant! The prac­ti­cal pur­pose of the table above is to rec­om­mend, based on the val­ue of the required amount of ther­mal ener­gy, the required pipe diam­e­ter dur­ing the selec­tion of pipe mate­ri­als for a res­i­den­tial heat­ing sys­tem.

Let’s look at an illus­tra­tive exam­ple:

There is a typ­i­cal house with a usable area of ​​250 m2. The build­ing is suf­fi­cient­ly insu­lat­ed and needs heat­ing at the rate of 1 kW per 10 square meters to cre­ate nor­mal liv­ing con­di­tions. m, that is, to cre­ate a com­fort­able tem­per­a­ture in the house, 25,000 watts of ther­mal ener­gy (max­i­mum) will be enough.

On a note: the first floor always requires more heat — about 2/3 of the total amount con­sumed.

Thus, out of 25 kW, heat­ing the first floor will require 15 kW, the sec­ond — 10 kW.

The house is equipped with an autonomous heat­ing sys­tem based on a dou­ble-cir­cuit boil­er. The radi­a­tors installed in the rooms are con­nect­ed in par­al­lel. The house has a wiring for two wings, with equal heat out­put. On the ground floor, the pow­er for each wing is 7500 watts. For the sec­ond floor, both wings require 5000 watts each.

A two-sto­ry house with a water heat­ing sys­tem based on an autonomous boil­er — in the con­text


The boil­er pro­duces 25 kilo­watts of ther­mal ener­gy for heat­ing the house. This means that for the heat main it is nec­es­sary to use polypropy­lene pipes and fit­tings with an inner diam­e­ter of 26.6 mm (at a feed rate of 0.6 m / s). This val­ue cor­re­sponds to the out­er diam­e­ter of the pipe 40 mil­lime­ters.

To sup­ply the branch­es on the ground floor, 1500 watts of heat will be required. Using the data from the table, we get the fol­low­ing:

  • at a flow rate of 0.6 m / s, the opti­mal diam­e­ter of the inner lumen of polypropy­lene pipes will be 21.2 mm — the iden­ti­cal exter­nal para­me­ter cor­re­spond­ing to this val­ue, accord­ing to the table, is 30 mm;
  • for each wing, pipe mate­r­i­al with an inner diam­e­ter of 16.6 mm is suit­able, which cor­re­sponds to Ø 25 mm of the out­er con­tour of the sec­tion of polypropy­lene pipes.

Now con­sid­er the pro­ce­dure for con­nect­ing heaters.

Water heat­ing radi­a­tors have an aver­age pow­er of 2 kilo­watts, there­fore, the­o­ret­i­cal­ly, pipes with a min­i­mum out­er diam­e­ter of 16 mm (PN16) are suit­able for their inser­tion into the cir­cuit. How­ev­er, in prac­tice it is rec­om­mend­ed to use polypropy­lene prod­ucts with an inter­nal sec­tion size of 13.2 mm and an out­er diam­e­ter of 20 mm (PN20), since the use of PN16 poly­mer pipes is con­sid­ered inap­pro­pri­ate due to low man­u­fac­tura­bil­i­ty.

The sec­ond floor is equipped with a 32 mm pipeline. Pipes and fit­tings Ø25 mm are used for each wing. With radi­a­tors, the pic­ture is the same as on the ground floor — the bat­ter­ies are con­nect­ed using PN20 pipes.


Based on the above exam­ple, for each sec­tion of the pipeline in the heat­ing sys­tem, it is pos­si­ble to select com­po­nents of the required diam­e­ter — includ­ing this, the effi­cien­cy of the heat­ing equip­ment will depend.

It should be remem­bered that the mate­ri­als for the pipeline in the heat­ing sys­tem are select­ed with the cal­cu­la­tion of com­pli­ance with the max­i­mum tech­ni­cal char­ac­ter­is­tics of an autonomous boil­er, despite the fact that in most cas­es the unit will oper­ate in nor­mal mode — in accor­dance with the spec­i­fied oper­at­ing para­me­ters.


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