Heating with electric convectors

Elec­tric con­vec­tor SKZS20 euro (STIEBEL ELTRON)

A flex­i­ble con­trol­lable heat­ing sys­tem based on con­vec­tor pan­els will allow you to set and main­tain an indi­vid­ual tem­per­a­ture regime in each room of the house –>
With this remote con­trol from NOBO, you can pro­gram the oper­a­tion of all con­vec­tor heaters installed in the house
Wall mount­ed con­vec­tor pan­el NOIROT (Cali­dou series)

High con­vec­tor series CNX2 from NOIROT
Sta­tion­ary wall con­vec­tor THS from ATLANTICTher­mo­stat ZSC-EL from NOBO

One of the advan­tages of con­vec­tor pan­els is that they are com­pact and com­pat­i­ble with almost any inte­ri­or. There are even options for dec­o­rat­ing the pan­els them­selves. True, it is bet­ter to entrust this work to spe­cial­ists.
The main thing- do not clut­ter up the elec­tric con­vec­tor with fur­ni­ture, which leads to a decrease in the effi­cien­cy of its work
As a result, the entire process of con­nect­ing the device takes a mat­ter of sec­onds, and if nec­es­sary, the pan­els can be eas­i­ly dis­man­tled and moved to anoth­er room.
For the con­ve­nience of con­nect­ing the pow­er sup­ply, some con­vec­tors have a spe­cial con­nec­tor
NOBO con­vec­tor con­trol unit

Wall con­vec­tor CNS 50–250 by STIEBEL ELTRON
Skirt­ing con­vec­tor of the Elite series from DIMPLEXThanks to the deflect­ing brack­ets, you can eas­i­ly wipe the dust behind the con­vec­tor pan­el dur­ing home clean­ing

The choice of the main heat­ing sys­tem of the cot­tageis not an easy task. Along with gas, liq­uid and sol­id fuel boil­ers, the oper­a­tion of which requires the sup­ply of gas com­mu­ni­ca­tions or a con­stant sup­ply of fuel, there are effi­cient elec­tric heat­ing sys­tems. Owarm floors we described above. BUTnow we will talk about a sys­tem based on elec­tric con­vec­tors that con­vert elec­tri­cal ener­gy into heat, which is trans­ferred using nat­ur­al air cur­rents.

There are floor (mov­able) and wall (sta­tion­ary) con­vec­tors. On the basis of the lat­ter, you can quick­ly and with­out sig­nif­i­cant costs install a heat­ing sys­tem in your home.

Any mod­ern elec­tric con­vec­tor has a hol­low rec­tan­gu­lar met­al body, which con­tributes to the for­ma­tion of nat­ur­al draft. ATthe low­er part of the hous­ing is equipped with a low-tem­per­a­ture heat­ing ele­ment (TEH) with a lamel­lar radi­a­tor. ATdur­ing oper­a­tion, the pan­el grad­u­al­ly pass­es cold air com­ing from the low­er inlets, and it flows around the heat­ing ele­ment. The heat­ed air flow ris­es and exits through the upper open­ings of the pan­el, dis­trib­ut­ing through­out the vol­ume of the room. Thus, heat trans­fer is car­ried out with the help of nat­ur­al air cir­cu­la­tion, which in physics is called con­vec­tion. Hence the name of the heater itself.

All elec­tric con­vec­tors are equipped with a reli­able secu­ri­ty sys­tem and turn off if a for­eign object gets on the heat­ing ele­ment or there is an obsta­cle to the exit of hot air. It is also manda­to­ry to pro­vide pro­tec­tion against an abrupt increase in volt­age.

Unlike tra­di­tion­al heat­ing devices (say, elec­tric fire­places or oil radi­a­tors), con­vec­tive wall mod­ules do not heat up so much in oper­a­tion: the tem­per­a­ture of the heat­ing ele­ment usu­al­ly does not exceed 100C, and the max­i­mum tem­per­a­ture of the out­er front sur­face of the pan­el, as a rule, does not rise above 60C. Com­pared to a floor heat­ing sys­tem, elec­tric con­vec­tors, at almost the same ener­gy cost, are much eas­i­er to install, oper­ate and repair, because they are placed on top of the fin­ished wall cov­er­ing and are eas­i­ly acces­si­ble for repair or replace­ment.

How­ev­er, all heat­ing sys­tems that use the prin­ci­ple of con­vec­tion have a com­mon sig­nif­i­cant draw­back: they heat the room uneven­ly, espe­cial­ly in height. Warm air streams, hav­ing a low­er den­si­ty, accu­mu­late under the ceil­ing, and the air tem­per­a­ture near the floor remains rel­a­tive­ly low (this dis­tin­guish­es con­vec­tors from warm floors). In addi­tion, the cir­cu­lat­ing cur­rents car­ry dust along with it, and over time it set­tles on the walls near the heaters in the form of dark stripes. There­fore, in the vast major­i­ty of con­vec­tors of the lat­est gen­er­a­tion, the air grilles that let the heat­ed air through are not locat­ed in the upper part of the pan­el, but on its front sur­face. Air deflect­ing lou­vers are locat­ed at a cer­tain, cal­cu­lat­ed angle of incli­na­tion, due to which the air flow is direct­ed not upwards, but into the cen­tral part of the room (ver­ti­cal­ly). ATas a result, warm and cold streams are mixed in the most opti­mal way, ensur­ing uni­form heat­ing of heat­ed rooms, and the trans­ferred dust does not set­tle on the walls. If the room is large, an addi­tion­al fan is installed to speed up heat­ing.

Heating elements…

The most inex­pen­sive con­vec­tors on our mar­ket are equipped with a heat­ing ele­ment in the form of an open incan­des­cent spi­ral. This sig­nif­i­cant­ly reduces the cost of devices (prices here range from $40 to $60, depend­ing on the mod­el), but lim­its their scope due to the low­er pro­tec­tion class. For exam­ple, pan­els from EWT (Ger­many) with a spi­ral ele­ment are not rec­om­mend­ed for instal­la­tion in wet rooms. In addi­tion, the coil has a rather high oper­at­ing tem­per­a­ture (160C), there­fore, dust decom­pos­es inten­sive­ly on it, and the ingress of com­bustible sub­stances on it can lead to a fire. But the air heat­ing rate increas­es, and if you are going to mount such equip­ment in util­i­ty or sec­ondary rooms, it becomes pos­si­ble to save mon­ey. The same con­vec­tors from EWT (mod­els with a height of 450mm, depth 240mm and either 660 or 760 longmm; pow­er- from 800 to 2000W) have a ther­mo­stat and a step pow­er reg­u­la­tor, and pan­els with a length of 760mm- the built-in fan pro­mot­ing more inten­sive heat­ing of space.

Most mod­ern con­vec­tor pan­els are equipped with a low-tem­per­a­ture heat­ing ele­ment, which con­sists of a steel tube, where the fil­a­ment is placed, and an alu­minum dif­fuser (radi­a­tor), which pro­vides more effi­cient heat trans­fer from the heater to the air. This is how the heat­ing ele­ments are arranged, for exam­ple, in con­vec­tors of the EVNA brand man­u­fac­tured by VIKA INTERNATIONAL (Kaza­khstan).Dne­propetro­vsk, Europe). More­over, the heat­ing ele­ment itself con­sists of two heat­ing rods, which allows you to turn on the heater either at full or at half pow­er.

But since the coef­fi­cient of lin­ear expan­sion dur­ing heat­ing of alu­minum is approx­i­mate­ly twice that of steel, the steel heat­ing ele­ment and the alu­minum radi­a­tor expand dif­fer­ent­ly: when heat­ed, they rub against each oth­er and wear out over time, and the heat­ing process itself begins to be accom­pa­nied by char­ac­ter­is­tic crack­ling. Vio­la­tion of the tight con­tact between the radi­a­tor and the heat­ing ele­ment makes heat trans­fer dif­fi­cult, which can result in local over­heat­ing and lead to the heat­ing ele­ment burnout. BUTit’s close to a fire haz­ard.

Heat constructor

When build­ing an autonomous heat­ing sys­tem of a pri­vate house from NOIROT con­vec­tors (mod­els Mem­o­prog and Eco6) a pro­gram­mer cas­sette can be used as a con­trol device. Com­plete­ly ready for oper­a­tion, it is sim­ply insert­ed into a spe­cial sock­et of one of the con­vec­tors, next to the built-in con­trol unit. Such a cas­sette is capa­ble of dri­ving, depend­ing on the mod­el, opti­mal­ly nine, and max­i­mum- even twen­ty heat­ing mod­ules. Anoth­er con­trol option- Withcen­tral con­sole. Some remotes can han­dle a very large num­ber of mod­ulesup to six­ty. ATin both cas­es, con­trol com­mands will be giv­en either through a spe­cial cable, or direct­ly through the sup­ply wiring using a car­ri­er fre­quen­cy sig­nal. But that’s not all. The com­mand to turn on, turn off or change the mode can be received by phone!
The sys­tem con­trolled in this way allows you to set and auto­mat­i­cal­ly main­tain an indi­vid­ual ther­mal regime in each room. The opti­mal heat­ing modes are select­ed and pro­grammed tak­ing into account the real need for heat by hours of the day, by days, weeks and even longer peri­ods of time. Thanks to this opti­miza­tion, it is often pos­si­ble to keep the aver­age ener­gy con­sump­tion at a lev­el of only 30% of the nom­i­nal. Recall that the sys­tem con­sists of com­plete­ly inde­pen­dent mod­ules (indi­vid­ual con­vec­tors), which strong­ly resem­bles a con­struc­tion kit. The user can, as from cubes, build heat­ing accord­ing to the planned scheme, dis­as­sem­ble and build again, remain­ing con­fi­dent in the con­stant reli­a­bil­i­ty of the devices. Despite the fact that only NOIROT has imple­ment­ed such a sys­tem, such flex­i­bil­i­ty and free­dom- a very good incen­tive for oth­er man­u­fac­tur­ers.

The most advanced mod­els of con­vec­tors are equipped with a monoblock heat­ing ele­ment, that is, the heat­ing ele­ment and the radi­a­tor form a sin­gle whole. Here, each man­u­fac­tur­er has its own know-how. For exam­ple, the French com­pa­ny NOIROT has devel­oped and patent­ed a heat­ing ele­ment called RX.Silence. The unique­ness of its design solu­tion- innichrome fil­a­ment, sur­round­ed by a dense back­fill of the finest mag­ne­sia pow­der and tight­ly pressed into a one-piece cast silu­min body with fins. More­over, the mate­ri­als are select­ed so that they have the same coef­fi­cient of ther­mal expan­sion, which means that the mutu­al dis­place­ments of struc­tur­al ele­ments dur­ing heat­ing and cool­ing are insignif­i­cant. This ensures the dura­bil­i­ty of the ele­ment and com­plete noise­less­ness of its oper­a­tion. BUTthe fins are designed so that the heat­ing ele­ment is “trans­par­ent” in ver­ti­cal pro­jec­tion, so that dust does not accu­mu­late on its sur­faces and does not burn out. A sim­i­lar design is for heat­ing ele­ments from NOBO (Nor­way), in which the fil­a­ment is placed in a quartz back­fill. The ser­vice life of such heat­ing ele­ments- from 15 to 20years.

…and thermostats

The pres­ence of a ther­mo­stat allows the elec­tric con­vec­tor to main­tain the set tem­per­a­ture in the room with great accu­ra­cy. Thanks to this device, the con­vec­tor pan­el acquires the abil­i­ty to inde­pen­dent­ly turn on and off when the air is heat­ed to a pre­de­ter­mined tem­per­a­ture. Thus, the device does not work con­stant­ly, but in the mode of short inclu­sions, which leads to a small ener­gy sav­ing.

Elec­tric con­vec­tors use both electro­mechan­i­cal and elec­tron­ic com­bined ther­mostats (withair tem­per­a­ture sen­sor). Dis­ad­van­tages of ther­mostats of the first type- rel­a­tive­ly low accu­ra­cy of air tem­per­a­ture mea­sure­ment (0.5–2FROM) and nois­i­ness (bimetal­lic sen­sors click when trig­gered, which caus­es some dis­com­fort for users, espe­cial­ly in the mid­dle of the silence of the night). ATelec­tron­ic sys­tems, sen­sors mea­sure the tem­per­a­ture of the incom­ing cold air approx­i­mate­ly every 40s and send a sig­nal to the ther­mo­stat, which main­tains the set mode with accu­ra­cy 0.1C. Such con­trol units 2–3 times more expen­sive, but more reli­able and absolute­ly silent. If you set the same tem­per­a­ture lev­el in ther­mostats of both types, the elec­tron­ic device will save mon­ey due to greater accu­ra­cy. 3–4% elec­tric­i­ty com­pared to electro­mechan­i­cal. In addi­tion, con­vec­tors can be equipped with elec­tron­ic ther­mostats with timers, which allow you to select dif­fer­ent tem­per­a­ture con­di­tions dur­ing the day, in the evening and at night, as well as every day of the week and sig­nif­i­cant­ly save ener­gy.

So, con­vec­tors of the Unique series from SIEMENS designed to work with a vari­ety of local and cen­tral con­trol devices. The sim­plest of them is Siemens Autosaver- Remov­able elec­tron­ic ther­mo­stat with timer. BUTthe most “tricked out” cen­tral timer-ther­mo­stat Siemens Digi­Heat using radio fre­quen­cy sig­nals is able to con­trol heat­ing from one room (Digi­Heat1) up to four room groups (Digi­Heatfour). The con­trol sig­nal is trans­mit­ted with­in a radius of up to 80m by radio (fre­quen­cy433MHz) to the remov­able receiv­er of each heater. The fol­low­ing modes are avail­able: Com­fort (5–30FROM), eco­nom­i­cal (5–30FROM), frost pro­tec­tion (5–15FROM). The tem­per­a­ture lev­el accord­ing to the pro­gram can change every hour of any day of the week.

Firms spe­cial­iz­ing in the pro­duc­tion of con­vec­tors pro­duce mod­els with and with­out a built-in ther­mo­stat. In the built-in ther­mo­stat, the sen­sor will be obvi­ous­ly less accu­rate, because it is affect­ed by the tem­per­a­ture of the con­vec­tor body. ATheat­ing mod­ules of this type, the reg­u­la­tor is usu­al­ly cal­i­brat­ed in rel­a­tive units and requires indi­vid­ual cal­i­bra­tion- it allows you to achieve a cor­re­spon­dence between the actu­al tem­per­a­ture in the room and the posi­tion of the reg­u­la­tor. The remote ther­mo­stat reg­u­la­tor is marked in degrees and takes into account the tem­per­a­ture of the point in space where it is installed. As a rule, the com­bi­na­tion ther­mo­stat is attached to the wall at a height 1–1.5m from the floor, prefer­ably with­out drafts. It should be borne in mind that at a dis­tance of 50cm and 1.5m from the floor, near the front door or win­dow, the tem­per­a­ture will be dif­fer­ent.

The same if sev­er­al con­vec­tors are installed in the room. It is more expe­di­ent to use one ther­mo­stat, usu­al­ly elec­tron­ic, for the entire group of heaters.This sig­nif­i­cant­ly reduces the over­all cost of the equip­ment. This ensures the flex­i­bil­i­ty of con­trol, that is, the exact main­te­nance of the required tem­per­a­ture in the room at any time.

For exam­ple, in NOIROT con­vec­tors, the switch can be set to the pro­gram­ming mode. ATIn this case, the heat­ing pan­els will be con­trolled accord­ing to a sin­gle pro­gram through an exter­nal (pur­chased addi­tion­al­ly) or inter­nal pro­gram­mer of one of the con­vec­tors. Pro­grams are record­ed on a spe­cial cas­sette placed in the con­trol unit. Heat­ing pan­els of the Melodie Evo­lu­tion series are equipped with a con­trol sys­tem with an elec­tron­ic ther­mo­stat pro­grammed for 4modes (com­fort, eco­nom­i­cal, anti-freeze and stop) and a switch designed for the same modes plus pro­gram­ming. ToCon­vec­tors can be con­nect­ed to a spe­cial Mem­o­prog con­trol cas­sette, which is pur­chased for a sep­a­rate fee. Tofor Super Spot series appli­ances, an Eco con­trol cas­sette is con­nect­ed6: the pro­grams already incor­po­rat­ed in it reg­u­late the oper­a­tion of heaters through­out the week, includ­ing week­ends.

Adjustable tem­per­a­ture range in mod­ern con­vec­tors- from 5–7until 28–30C. Using the pos­si­bil­i­ty of pro­gram­ming, you can set any oper­at­ing modes. For exam­ple, if you come to your coun­try house exclu­sive­ly for the week­end, you can set the sys­tem in such a way that the min­i­mum tem­per­a­ture is main­tained on week­days (+7C) with min­i­mal ener­gy con­sump­tion, and by your arrival, the con­vec­tors heat­ed the build­ing to a com­fort­able lev­el. And, most valu­able, main­tain­ing a pos­i­tive tem­per­a­ture in your absence (this is called the “anti-freeze” mode) will help to avoid emer­gency sit­u­a­tions in rooms where there are water locks (kitchen, bath­room, toi­let), and will favor­ably affect the dura­bil­i­ty of load-bear­ing struc­tures. ATEuro­pean con­di­tions are not uncom­mon- emer­gency shut­downs of pow­er sup­ply. As a rule, the heat stored in the house lasts for hours at 20–30. Accord­ing to exist­ing reg­u­la­tions, the pow­er sup­ply should be restored much ear­li­er. As soon as the net­work oper­a­tion resumes, the elec­tric con­vec­tors will start work­ing. Andhow­ev­er, if you plan to leave the house for a long time, it is bet­ter to play it safe and drain all avail­able water seals.

Firm Mod­el Pow­er, W Notes Price, $
NOIROT Series Spot E II 750‑2000 Height 440mm 115–169
Axane Series 750‑2000 Height 440mm 126–178
Melody Evo­lu­tion Series 750‑2000 High, 650mm 162–212
750‑1500 Skirt­ing, 220mm 173–213
Mem­o­prog - Con­trol cas­sette 57–167
Eco‑6 - Con­trol cas­sette 82
NOBO C2F series 250‑1500 Height 200mm 98–146
C4F series 500‑2000 Height 400mm 113–164
K4N series 250‑2000 Height 400mm, only for rooms with high humid­i­ty 82–148
R 80 XSC - Sin­gle elec­tron­ic ther­mo­stat 23
R80 PDE - Dou­ble elec­tron­ic ther­mo­stat with timer
(9 fixed pro­grams)
62
R 80 UDF - Dou­ble elec­tron­ic ther­mo­stat with timer
(12 fixed pro­grams)
88
THERMOR - 500‑2000 All types of pan­els 66–144
SIEMENS Basic Series 400‑2000 200 and 400 height mod­elsmm 75–113
Com­pact Series 500‑3000 Height 425mm 100–172
Com­plete Series 300‑1500 Skirt­ing boards, 200mm 109–142
DIMPLEX Elite series; 6mod­els of var­i­ous stan­dard sizes and capac­i­ties (withstep 250W) 500‑2000 Height of all pan­els 174mm 35–86
TD901 - Bimet­al ther­mo­stat
(max. load 22BUT)
twen­ty
DTK-DP - Built-in ther­mo­stat
(max. load 17BUT)
twen­ty
4800A - Elec­tron­ic ther­mo­stat
(max. load 17BUT)
60
ELEGANCE Mod­els in four sizes 500‑2000 Height of all pan­els 420mm 60–117
Cor­po­ra­tion “DIPOLE”
(G.Sara­tov)
VPS-2000 2000 Height 520mm, length 320mm, pan­el depth 82mm 40
JSC “MAYAK”
(G.Vin­nit­sa, Europe)
con­vec­tor “Ther­mia” of sev­en stan­dard sizes 500‑2000 Height of all pan­els 460mm 15–40
EWT Cli­ma 215NT 2000 660450200mm 47
Cli­ma 240TLG 2000 755450220mm;
mod­el with fan
77
STIEBEL ELTRON CNS series; 8 mod­els of var­i­ous sizes and capac­i­ties (withstep 250W) 500‑2500 Height of all pan­els 450mm 76–109
ATLANTIC Series F17‑3, with elec­tro-mechan­i­cal ther­mo­stat 500‑2500 Height of all pan­els 450mm 75–118
Series F117, with elec­tron­ic ther­mo­stat 500‑2000 Height of all pan­els 450mm 80–114

Size matters

Accord­ing to their geo­met­ric dimen­sions, con­vec­tor pan­els are divid­ed into three main groups: high (height 460–650mm), medi­um (no more than 330mm) and nar­row, or plinth (height 150–200mm). Dimen­sions in length vary, depend­ing on the pow­er and ver­sion of the device, from 295 to 1035mm. BUThere the depth is almost con­stant- no more than 90mm.

As a rule, man­u­fac­tur­ing firms pro­duce mod­els with a capac­i­ty of 0.5 to 3kW in steps of 250W and weight from 3 to 9kg. Andpow­er, and weight depend on the dimen­sions of the pan­els. High pan­els cre­ate draft as in a con­ven­tion­al chim­ney, sig­nif­i­cant­ly increas­ing heat trans­fer, so their length is neg­li­gi­ble. Skirt­ing con­vec­tors are designed for instal­la­tion under low win­dows or stained-glass win­dows. The tem­per­a­ture of the heat­ing ele­ment in mod­els of this type is some­what low­er than that of tall appli­ances, and in order to main­tain the heat dis­si­pa­tion of the con­vec­tor, it is made longer (some­times up to2.5m). ATAs a result, low heaters work just as effi­cient­ly as high ones. By the way, skirt­ing con­vec­tors cre­ate small­er con­vec­tion flows, pro­vid­ing more uni­form heat­ing of the air, espe­cial­ly in the low­er part of the room space.

Today in domes­tic stores you can find con­vec­tor elec­tric heaters from com­pa­nies such as ATLANTICNOIROT, THERMOR (France), DIMPLEX (Cana­da), NOBO (Nor­way), ELEGANCE (Fin­land), STIEBEL ELTRON, EWT, SIEMENS (Ger­many), PROTHERM (Czech Repub­lic) and oth­ers. Elec­tric con­vec­tors are also pro­duced in EU and neigh­bor­ing coun­tries by the DIPOL enter­pris­es (St.Sara­tov), ​​“DELSOT” (city ofMiass), plant “LADOGA” (Mr.Kirovsk), com­pa­nies “MAYAK”, “VIKA Inter­na­tion­al” (Europe) and oth­ers. Euro­pean devices in terms of tech­ni­cal char­ac­ter­is­tics are not much infe­ri­or to import­ed ones, but are not so per­fect in design.

Cap­i­tal costs for the instal­la­tion of the main heat­ing sys­tem of a pri­vate house based on elec­tric con­vec­tors range from $4 to $8 for 1m2 heat­ed area. It is much cheap­er than installing under­floor heat­ing or a stan­dard heat­ing sys­tem with a boil­er, cir­cu­la­tion pump, expan­sion tank, shut­off valves, heavy radi­a­tors, etc.e. In addi­tion, time is sig­nif­i­cant­ly saved, and the scale of work itself is incom­pa­ra­bly small­er. Imag­ine at least that instead of pipes you only have to “throw” elec­tri­cal wiring. The pan­els them­selves look quite ele­gant and fit per­fect­ly into any inte­ri­or.

Helpful Hints

  • When choos­ing the pow­er of a con­vec­tor, the fol­low­ing rule is used: for build­ings with nor­mal ther­mal insu­la­tion, approx­i­mate­ly 70W per 1m2; for build­ings with poor ther­mal insu­la­tion- already 100–130 W/m2. The total space heat­ing pow­er can be cal­cu­lat­ed from the table below.

    Sim­pli­fied choice of elec­tric con­vec­tor pow­er

    Room type Bath­room Kitchen Chil­dren bed­room Bed­room Liv­ing room
    Room dimen­sions, m2 5–7 7–11 7–13,13–18 15–21 20–28
    Heat­ing pow­er, W 500 500 1000–1250 1500 2000
  • Anoth­er vari­ant- based on the vol­ume of the room, based on the cal­cu­la­tion: 40W per 1m3. Addi­tion­al heat loss­es due to exter­nal walls should also be tak­en into account. If the room is angu­lar or has a large glass area, it is advis­able to select equip­ment with a pow­er reserve. This will sim­ply affect the rate of heat­ing the space to a giv­en tem­per­a­ture. If you take a mod­el with a delib­er­ate­ly low pow­er, it may hap­pen that the device sim­ply does not reach the desired tem­per­a­ture regime and will work all the time.

  • For the most pow­er­ful pan­el (at least 2 kW) it is nec­es­sary to select elec­tri­cal wiring with a con­duc­tor cross sec­tion of 2.5mm2. The main thing to focus on- the main core of the cable must cor­re­spond to the total pow­er of the con­sumed cur­rent of all pan­els in the house.

The edi­tors would like to thank WHITE GUARD Trade House and GRAND-OTEX-REGION, RUSKLIMAT, SVIGI com­pa­nies for their help in prepar­ing the mate­r­i­al.

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