Burn, burn bright!

Sci­en­tists have proven that the vast major­i­ty of peo­ple feel com­fort­able when the room tem­per­a­ture is 18–24C. Today, there are var­i­ous heat­ing devices on sale that are capa­ble of main­tain­ing the tem­per­a­ture in the house (or at least in one of its rooms) with­in the spec­i­fied lim­its for a long time, regard­less of the vagaries of the weath­er, in the cold sea­son. Tothese include fire­places with a closed fire­box, endowed with the abil­i­ty to accu­mu­late heat.

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Pho­to by V.Bal­asho­va Pho­to 6

1–6.Fire­places and stoves, closed cast-iron or steel fire­box­es of which are built into struc­tures made of tiles pre-assem­bled in pan­els, for a long time (at least 2–4h) heat the room after the fire­wood has burned out. In terms of design and appear­ance, tiled claddings are very diverse.

ToUnfor­tu­nate­ly, due to the small mass (no more than 100–190kg) a closed fire­place insert in terms of its ther­mal capa­bil­i­ties does not dif­fer from stoves of low heat capac­i­ty: bour­geois stoves, tem­po­rary brick stoves andt.n. Fire­places equipped with a closed fire­box (espe­cial­ly thin-walled), on one lay­ing of fire­wood, effec­tive­ly heat the room for only a short time (no more than 1–2h). While the fire is burn­ing, the air tem­per­a­ture ris­es sharply, but there is almost no heat accu­mu­la­tion in the build­ing (due to con­tact with warm air, house struc­tures heat up extreme­ly slow­ly). Soon after the flame goes out, it becomes cold, because with prop­er ven­ti­la­tion in just 1h all the air, in which the heat gen­er­at­ed by the fire­place is “dis­solved”, is replaced by cool out­door air. In order to get enough heat, the fire­place insert must be con­stant­ly fed with por­tions of fuel, which requires a cer­tain skill, which is inher­ent only in pro­fes­sion­al stok­ers, and for home­own­ers accus­tomed to com­fort, this is incon­ve­nient.

From the depths of cen­turies

Pho­to by V.Bal­asho­va
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nord­peis Pho­to 8
Tulikivi Pho­to 9

7.Fire­place with closed hearth- dec­o­ra­tion for any room of a coun­try house, whether it be a kitchen, a draw­ing room or a bed­room. But such a device can become an effec­tive heat gen­er­a­tor only if there is a mas­sive cladding or a heat accu­mu­la­tor.
8–9.Tal­co­mag­ne­site- good mate­r­i­al for pro­duc­tion of fur­naces and chim­ney fac­ings for the closed fire cham­bers. This stone has a heat capac­i­ty 2.5 times greater than that of oven bricks.

ATAt the same time, stoves with a large heat capac­i­ty (the Euro­pean stove, which heat­ed, fed and treat­ed more than one gen­er­a­tion of our ances­tors) are among them, the dis­ad­van­tages of fire­place inserts and oth­er stoves of low heat capac­i­ty are not char­ac­ter­is­tic. Such an oven can weigh from 500–750kg to sev­er­al tons. Of course, before it heats up to the desired tem­per­a­ture, it will take quite a long time, some­times sev­er­al hours (unlike a fire­place, which starts heat­ing the room as soon as the first torch lights up in it,- due to the radi­a­tion of ther­mal waves through the glass of the fire­box). But on the oth­er hand, the heat stored in the mass of the oven brick after the fuel burns out com­pen­sates for the heat loss of the house, not allow­ing the rooms for 10–24h nei­ther over­heat nor over­cool. Real­iz­ing this, many man­u­fac­tur­ers of fire­places offer var­i­ous tech­ni­cal solu­tions that allow you to trans­fer a fire­place with a closed fire­box from the rank of fur­naces of low heat capac­i­ty to the rank of fur­naces of high heat capac­i­ty, “teach” it to store heat for future use. We will talk about some of these “recipes”.

heavy dress

First of all, let’s present a tech­ni­cal solu­tion that is quite expen­sive, but very com­fort­able, envi­ron­men­tal­ly friend­ly and adapt­ed to our cli­mate. These are fire­places with heat-retain­ing lin­ing, which is a mon­u­men­tal struc­ture, often from floor to ceil­ing (it is sup­plied togeth­er with a fire­place insert in the form of a set of ele­ments ready for instal­la­tion). Fire­places with such fac­ings are placed against the wall, in the cor­ner of the room, and some­times in the mid­dle of the room. Heat accu­mu­lates in the stone mass of their fac­ings and heats the room for 4–15h after the fuel burns out. Heat trans­fer from heat-retain­ing fire­place lin­ings is usu­al­ly uni­form, the air in the room remains warm for a long time, while the rel­a­tive humid­i­ty is main­tained at an opti­mal lev­el (about 40%), and a par­tic­u­lar­ly pleas­ant atmos­phere reigns in the house. Heat accu­mu­lat­ing claddings from the best man­u­fac­tur­ers are dis­tin­guished by their ele­gant design, pre­cise fit­ting of ele­ments (heavy blocks of stone or con­crete) and ease of instal­la­tion. Since the claddings are often assem­bled using met­al ties, they can be quick­ly and eas­i­ly assem­bled and just as quick­ly dis­man­tled to be trans­port­ed to a new “place of res­i­dence”.

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Pho­to by V. Kovalev
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Com­put­er graph­ics
N. Sama­ri­na
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13–14.To increase the heat trans­fer time, the fur­naces are ribbed and lined with fire­clay.
fif­teen.The ther­mo­con­crete Brun­ner chim­ney is often built into the wall behind the fire­place.
16.Some fur­nace mod­els are equipped with flue gas heat exchang­ers.- water”, which allow to accu­mu­late heat in the liq­uid fill­ing the heat­ing sys­tem.

ATunlike heat-accu­mu­lat­ing lin­ings, ther­mal­ly insu­lat­ed lin­ings almost do not accu­mu­late heat in their mass. More­over, there is prac­ti­cal­ly no heat trans­fer through the heat-insu­lat­ed lin­ing to the fire­place room. To increase the heat capac­i­ty of the fire­place in this case, mas­sive closed fur­naces with thick walls and heat accu­mu­la­tors are required, pass­ing through which the flue gas­es from the insert are sent to the chim­ney.

When choos­ing a fire­box, first of all, pay atten­tion to heavy cast-iron mod­els. Great choice- fire­box Ked­dy (Kennedy­grup­pen, Swe­den). The thick­ness of the walls of the mono­lith­ic body of Ked­dy fire­box­es in some places reach­es 18mm, which not only allows you to store heat, but also ensures their high strength. For exam­ple, Ked­dy 520 with curved glass with a capac­i­ty of 14kW weighs 145kg and costs about 70thou­sandrub. Seguin Duter­ies (France) offers for 45thou­sandrub. fire­box Kite­flam with walls 8–12 thickmm (it is pro­vid­ed with a sev­en-year war­ran­ty). Thick-walled mas­sive fire­box­es are avail­able from Tar­na­va (Poland) and Jotul (Nor­way).

You can con­sid­er the pos­si­bil­i­ty of buy­ing a steel insert, but nec­es­sar­i­ly cov­ered from the inside (lined) with plates of heat-absorb­ing fire­clay clay. When choos­ing a sim­i­lar design, it must be remem­bered that in fire­box­es with glass larg­er than 7070see fire­clay is not always used- there are mod­els with a lin­ing of ver­mi­culite, which is not capa­ble of accu­mu­lat­ing heat. Of inter­est is the Axis tech­nique (France), lined from the inside with plates of chamotte clay with a thick­ness of 6cm.

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17–20.The role of the chim­ney sec­tion above the fire­box can be played by heat accu­mu­la­tors made of stone(17,19,20) and cast iron(eigh­teen).

Direct­ly above the closed fire­place insert, in the hood of the fire­place lin­ing, you can install a small heat accu­mu­la­tor made of steel or cast iron, which will also be a sec­tion of the chim­ney. A cast iron chim­ney-con­vec­tor finned on the out­side is accept­able, for exam­ple Tar­na­va. If the dimen­sions of the cap allow, it is per­mis­si­ble to use two such heat accu­mu­la­tors at once, installing them one above the oth­er. Steel con­vec­tor chim­neys in the form of a piece of pipe, to which 4–12 flat ribs are weld­ed, are usu­al­ly lighter than cast iron ones. They are good only for increas­ing the effi­cien­cy of the insert dur­ing fuel com­bus­tion (an increase in heat removal occurs due to the larg­er heat exchange sur­face of the chim­ney with room air). If you buy a steel chim­ney-con­vec­tor equipped with a cylin­dri­cal met­al mesh (the annu­lar space between the chim­ney and the mesh is filled with frag­ments of tal­co­mag­ne­site or oth­er heat-inten­sive mate­r­i­al), the heat accu­mu­la­tor will turn out to be excel­lent. Such a design has, for exam­ple, the Feringer chim­ney-con­vec­tor, the length of which- 100cm and diam­e­ter- 11.5see inits grid can be loaded up to 50kg of stones; it costs about 2200thou­sandrub.

If the strength of the fire­place insert is high enough, a heat accu­mu­la­tor made of ther­mo­con­crete and (or) fire­clay can be placed direct­ly above it. Such heat accu­mu­la­tors are usu­al­ly made in the form of a “sand­wich” of sev­er­al heavy plates, in which there are through chan­nels for the pas­sage of flue gas­es (more often there are sev­er­al flue chan­nels, which allows increas­ing the con­tact area of ​​flue gas­es with the heat stor­age mate­r­i­al). The pack­age of stone plates can be tight­ened with met­al ties or a steel hoop.

Schmid is one of the lead­ers in terms of pro­duc­tion of heat accu­mu­la­tors mount­ed above fire­place inserts. The “light” heat accu­mu­la­tor of this com­pa­ny, made of chamotte, is ringed with stain­less steel on the out­side. It accu­mu­lates ther­mal ener­gy dur­ing the oper­a­tion of the fire­place and gives it to the room after the end of com­bus­tion even­ly and for a long time (up to 2–3h). “Heavy” fire­clay heat accu­mu­la­tor is ringed out­side with ther­mo­con­crete. The effi­cien­cy of this sys­tem is high­er- up to 3–4h. The air in the room dur­ing its use remains warm longer, the rel­a­tive humid­i­ty is main­tained at an opti­mal lev­el. The cost of a heat accu­mu­la­tor of sev­en plates in EU is approx­i­mate­ly 38thou­sandrub.

A heat accu­mu­la­tor locat­ed in the space above the chim­ney cas­sette is some­times includ­ed in the “heat-stor­ing cladding” kit+closed fire­place insert”. Such a tan­dem pro­vides a seri­ous increase in the heat trans­fer time of the fire­place. For exam­ple, Ked­dy brand­ed lin­ings for inserts are made of vol­canic pumice- a fair­ly light mate­r­i­al, which is nev­er­the­less a good heat accu­mu­la­tor. Inside the cladding, a place is pro­vid­ed for a heat accu­mu­la­tor mount­ed above the fur­nace made of tal­co­mag­ne­site plates. For exam­ple, the Regal / Mis­tral (Kennedy­grup­pen) mod­el weighs about 800kg (togeth­er with the fire­box, lin­ing and heat accu­mu­la­tor). Accord­ing to the man­u­fac­tur­er, the heat gen­er­a­tor cools down 10–15h, not allow­ing the cold to pen­e­trate the house. You can buy Regal/Mistral for 150thou­sandrub.

Shield against the cold nord­peis

I must say that it is often impos­si­ble to install a heat accu­mu­la­tor above the fire­place insert due to the design fea­tures of the fire­box or lin­ing (in the hood area). ATIn this case, flue gas­es can be dis­charged into the chim­ney through a floor heat stor­age locat­ed behind the fire­place or even on the floor above. Alas, such sys­tems of long-term heat accu­mu­la­tion are non-volatile (up to 12–15h) can not always be done. The fact is that inside the floor heat accu­mu­la­tor, flue gas­es often fol­low a com­plex sys­tem of smoke chan­nels with a suf­fi­cient­ly large aero­dy­nam­ic resis­tance. Andthe rar­efac­tion that a fire­place chim­ney is capa­ble of cre­at­ing is far from always enough to make the smoke “sweep out of the house.” There­fore, the chim­ney head locat­ed on the roof must be equipped with an elec­tric fire­place fan designed to enhance draft, for exam­ple Tur­bo­camino (O. Erre, Italy) cost­ing 20thou­sandrub.

Among the ready-made solu­tions, it is worth not­ing the Brun­ner mod­u­lar heat stor­age device (Ger­many). It is col­lect­ed from heavy (about 20kg) cor­ner elbows and at least weighty straight ele­ments made of ther­mo­con­crete,- all of them are easy to artic­u­late and very durable. ATcross sec­tion of such a “stone chim­ney” is an octa­he­dron (diag­o­nal- around 30cm) with a round flue gas hole in the mid­dle. Work­ing tem­per­a­ture- before 900FROM. Mas­sive heat accu­mu­la­tors can be cre­at­ed from such ele­ments, if nec­es­sary.- a rather com­plex shape. Most often they are built into the struc­ture of the inner wall of the house behind the fire­place.

More bud­get solu­tion- con­nec­tion of a fire­place to a heat­ing shield, made in the form of a small attached or built-in wall with flue gas chan­nels inside (usu­al­ly 2–3 smoke turns are made), the mass of which is 600‑1000kg. Dur­ing the oper­a­tion of the fire­place, the flow of flue gas­es is removed from the house through the heat­ing shield, giv­ing off heat to the fire­clay lin­ing of its inter­nal chan­nels. This solu­tion increas­es the effi­cien­cy of a fire­place with a closed fire­box up to 80–90%. To use the fire­place in the warm sea­son, in order not to over­heat the house, it is log­i­cal to pro­vide for a sum­mer mode, when hot gas­es from the insert go through the shield along a short path or are gen­er­al­ly removed direct­ly into the chim­ney, bypass­ing the heat­ing shield (for this, a flow split­ter is built in direct­ly behind the fire­place insert flue gas­es with two dampers). Since shields of this type are made for a spe­cif­ic coun­try house and fire­place, it is most like­ly impos­si­ble to do with­out the ser­vices of a qual­i­fied spe­cial­ist.

Cozy hearth in the apart­ment

Pho­to by V.Bal­asho­vaBurn, burn bright!	Pho­to by V.Bal­asho­va Installing a sol­id fuel fire­place in a city apart­ment is not so easy. To do this, you must obtain per­mis­sion from the exec­u­tive author­i­ties. BUTHere, a biofire­place can be installed and oper­at­ed with­out inform­ing any­one about it. Biofire­places do not require con­nec­tion to a chim­ney, but nev­er­the­less they give a real, “live” fire, and in the process of burn­ing the alco­hol bio­fu­el poured into them, soot, soot, ash or any harm­ful sub­stances are not formed.- only water vapor and a small amount of car­bon diox­ide. Biofire­places can be installed in any room of the apart­ment, whether it is a liv­ing room, an office or a bed­room. Ther­mal pow­er of these devices- 0.5–3kW.

fire­place boil­er

Water has a high heat capac­i­ty, which is at least 5times the heat capac­i­ty of any stone. Lead­ing man­u­fac­tur­ers of closed fire­place inserts pro­vide for the pos­si­bil­i­ty of accu­mu­lat­ing the heat of flue gas­es in a mass of water or antifreeze that fills the heat­ing sys­tem. For this, spe­cial fire­box­es are pro­duced.- fire­places-boil­ers. Among the fire­places-boil­ers, we note the mod­els HWM-Konzept, Kom­pakt-Kessel B4/B5/B6 (Brun­ner). Godin fire­places (France) are well-known in our coun­try: mod­els 851 CH, L’Os­mos 680116, and Libourne 680117 with a black fire­box dec­o­rat­ed with steel inserts. The cost of these devices- 137–280thou­sandrub. Each of these mod­els can trans­fer up to a max­i­mum of 15 kW of heat to the heat car­ri­er of the heat­ing sys­tem, while the nom­i­nal pow­er of the fur­naces is 19–23kW. Worth men­tion­ing is the I18 Jotul with flue gas heat exchang­er- water.

It is incon­ve­nient to use fire­places-boil­ers as the only heat gen­er­a­tor for a coun­try house of per­ma­nent res­i­dence, since you will have to hire a stok­er. BUThere in hous­es vis­it­ed in the cold sea­son by short trips, they ful­ly jus­ti­fy them­selves. Some mod­els of fire­places-boil­ers are also used to heat the water of the DHW sys­tem.

Devel­op­ing this top­ic, it must be said that in Europe, where ener­gy sav­ing has recent­ly been put at the fore­front, vol­u­met­ric heat stor­age boil­ers (multi­boil­ers) are used that accu­mu­late the heat of the fire­place. They are installed in the base­ment of a coun­try house. Tooth­er heat sources are also con­nect­ed to such a heat accu­mu­la­tor, for exam­ple, ground source heat pumps, a gas or liq­uid fuel boil­er, a solar col­lec­tor, as well as heat con­sumers: radi­a­tors, under­floor heat­ing, a hot water sup­ply sys­tem, heat exchang­ers of ven­ti­la­tion units. Such a heat stor­age sys­tem is con­trolled by com­plex micro­proces­sor automa­tion that takes into account each kilo­watt-hour of stored ener­gy, ana­lyzes the cur­rent needs of the house for heat and uses all the pos­si­bil­i­ties to min­i­mize heat gen­er­a­tion costs in order to reduce oper­at­ing costs and not dam­age nature.

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