The choice of liquid for home heating, what to use?


The rather harsh cli­mate of the mid­dle lane forces us to use heat­ing appli­ances for more than half of the cal­en­dar year. Such intense oper­a­tion requires from the heat­ing equip­ment not only high per­for­mance, but also reli­a­bil­i­ty. The cor­rect func­tion­ing of the heat­ing sys­tem depends on the qual­i­ty of its instal­la­tion and the char­ac­ter­is­tics of the coolant used. One of the press­ing ques­tions of home­own­ers and design spe­cial­ists is the choice of a heat car­ri­er for heat­ing a pri­vate house: which is bet­ter — anti-freeze or water?

It is worth remem­ber­ing that any coolant has both advan­tages and dis­ad­van­tages, that is, an option that is ide­al from all sides sim­ply does not exist. When choos­ing, con­sid­er the fol­low­ing cri­te­ria:

  • cur­rent oper­at­ing con­di­tions;
  • type of pump­ing units;
  • type of boil­er equip­ment.

The main prob­lem of ther­mal equip­ment in dif­fi­cult cli­mat­ic con­di­tions is the freez­ing of the coolant dur­ing the onset of cold weath­er. For the unin­ter­rupt­ed oper­a­tion of the instal­la­tion at any time of the year, you should use a type of coolant that pro­vides high-qual­i­ty heat­ing of all rooms and has the fol­low­ing prop­er­ties:

  • indi­ca­tor of aggres­sive­ness to met­als;
  • resis­tance to low tem­per­a­tures;
  • no ten­den­cy to pre­cip­i­tate;
  • no aggres­sive effect on seal mate­ri­als;
  • oper­a­tional sta­bil­i­ty.

In the oper­at­ing tem­per­a­ture ranges, any coolant for the heat­ing sys­tem of a coun­try house is able to oper­ate smooth­ly for a long time, how­ev­er, going beyond these lim­its is fraught with seri­ous changes in their phys­i­cal and qual­i­ta­tive char­ac­ter­is­tics. If we con­sid­er the coolant from the point of view of safe­ty, then it must have such qual­i­ties as non-tox­i­c­i­ty and a high vapor igni­tion tem­per­a­ture. An impor­tant cri­te­ri­on in the selec­tion process is the cost of the liq­uid, which is why it should not be too expen­sive for the own­er, and if the price is quite high, then the coolant should retain its prop­er­ties and vol­ume for as long as pos­si­ble.

Water as a heat carrier

Of course, water belongs to the cat­e­go­ry of the cheap­est heat car­ri­ers. In addi­tion to cheap­ness, one can con­fi­dent­ly declare its envi­ron­men­tal safe­ty and wide­spread avail­abil­i­ty. If a leak does occur, then it is not dif­fi­cult to restore the required vol­ume in the instal­la­tion, you just need to add a few liters of liq­uid to a spe­cial tank. It is worth remem­ber­ing that water always con­tains a lot of impu­ri­ties: chlo­rine, iron, salts, which accu­mu­late on the walls when they pre­cip­i­tate and form hard-to-remove scale, which affects the degree of heat trans­fer of pipes, leads to over­heat­ing of the equip­ment and dis­ables it.

In addi­tion, met­al ele­ments inevitably enter into an oxida­tive reac­tion with the liq­uid, which leads to cor­ro­sive changes.

Water tends to expand sig­nif­i­cant­ly when it freezes, so the lack of cir­cu­la­tion in the cold sea­son can dis­able the heat­ing instal­la­tion for a long time, break­ing the pipes. In no case should a sys­tem filled with liq­uid be left unat­tend­ed dur­ing the heat­ing sea­son in order to avoid freez­ing, just a few days — and expen­sive wiring can become unus­able. The forced heat­ing sys­tem is often pow­ered by elec­tric­i­ty, so when it is turned off or the pres­sure in the pipeline drops, the water can sim­ply freeze in the pipes, and this is fraught with seri­ous prob­lems. Unlike antifreeze, water expands when cooled below +4°C and dur­ing heat­ing, it must also be tak­en into account that it must be changed annu­al­ly.

If you read the oper­at­ing instruc­tions for the heat­ing boil­er, then all man­u­fac­tur­ers unan­i­mous­ly argue that dis­tilled water should be the coolant, since it is com­plete­ly free of all impu­ri­ties. The main dis­ad­van­tage of this approach is the cost, com­pa­ra­ble to buy­ing a good antifreeze.

Before fill­ing the instal­la­tion, it is nec­es­sary to thor­ough­ly clean the pipes and heat­ing devices with plain water. To improve the qual­i­ty of heat trans­fer and extend the life of the boil­er, it is rec­om­mend­ed to add spe­cial addi­tives to dis­tilled water.

Antifreeze liquids as a heat carrier


The use of antifreeze in heat­ing devices is more rel­e­vant for severe win­ters char­ac­ter­is­tic of the mid­dle cli­mat­ic zone. It has a much low­er freez­ing point com­pared to plain water, which will reli­ably pro­tect the heat­ing instal­la­tion from dam­age due to liq­uid freez­ing, even if elec­tric­i­ty or gas is turned off for a long time. The unique prop­er­ties of the flu­id, as well as addi­tion­al addi­tives, pro­tect pipes from scale and cor­ro­sion. In our cli­mate, antifreeze is uncon­di­tion­al­ly the best option for refu­el­ing heat­ing devices.

What is antifreeze? The main com­po­nent here is propy­lene gly­col or eth­yl­ene gly­col, to which a sig­nif­i­cant amount of water has been added, as well as tar­get­ed addi­tives.

The con­cen­tra­tion of propy­lene gly­col in the com­po­si­tion of antifreeze deter­mines its frost resis­tance, the more it is, the low­er should be the tem­per­a­ture at which the com­po­si­tion begins to crys­tal­lize. To reduce the cor­ro­sive effect of the coolant, spe­cial inhibitors are used — chem­i­cal com­pounds that slow down the process of the liq­uid enter­ing into a reac­tion with met­al and oth­er sub­stances. To pre­vent sludge for­ma­tion, the com­po­si­tion includes a scale inhibitor, which pre­vents the for­ma­tion of foam dur­ing cir­cu­la­tion and reduces the risk of dis­so­lu­tion and swelling of the seals.

Antifreeze, as a heat car­ri­er for heat­ing, does not freeze with­in the oper­at­ing tem­per­a­ture range, but if hard­en­ing does occur, it does not expand like water and does not pro­voke the destruc­tion of the heat­ing instal­la­tion. Freez­ing, it becomes gel-like and does not change its vol­ume; return­ing to a liq­uid state does not have any con­se­quences for the coolant and equip­ment.

Today in spe­cial­ized stores you can find antifreezes with a min­i­mum tem­per­a­ture of ‑65 or ‑30 degrees. If nec­es­sary, the con­cen­tra­tion of the com­po­si­tion can be changed by adding dis­tilled water to it. The chem­i­cal com­po­si­tion of the flu­id is designed to oper­ate for 10 sea­sons or 5 years, after this time, all antifreeze in the sys­tem must be changed.

See also: Anti-freeze as a heat­ing sys­tem for a pri­vate house

With the many advan­tages of antifreeze, do not for­get about its short­com­ings. If we com­pare the oper­at­ing tem­per­a­ture of anti-freeze and water, it turns out that the heat capac­i­ty of anti-freeze is more than 15% low­er, there­fore, it accu­mu­lates heat worse and gives it off worse. There­fore, the con­sumer is forced to buy more pow­er­ful ther­mal equip­ment and spend more resources to main­tain the desired tem­per­a­ture. Due to the increased vis­cos­i­ty of antifreeze, and it is 5 times high­er than water, a pow­er­ful cir­cu­la­tion pump will be required to main­tain the required pres­sure. At the same time, elec­tric­i­ty con­sump­tion will increase by 10%. Keep­ing in mind that antifreeze does not expand when freez­ing, it should be borne in mind that when heat­ed, its ther­mal expan­sion is much greater than that of water, there­fore, when using it, a larg­er expan­sion tank is need­ed. In addi­tion, when over­heat­ed, antifreeze can per­ma­nent­ly lose its prop­er­ties.

Experts rec­om­mend deter­min­ing the type of coolant even before installing the heat­ing sys­tem, it is this approach that guar­an­tees the long ser­vice life of all devices, spon­ta­neous retrain­ing can be fraught with seri­ous trou­bles and lengthy repairs.

The chem­i­cal com­po­si­tion of anti-freeze is quite aggres­sive: it reacts with gal­va­nized sur­faces, caus­ing irrepara­ble dam­age to tech­ni­cal ele­ments, at the same time, such a neigh­bor­hood changes the com­po­si­tion of the coolant and con­tributes to the for­ma­tion of sed­i­ment, which can block the entire sys­tem. Rub­ber gas­kets are also sen­si­tive to this envi­ron­ment, so they will have to be changed much more often than when using water heat­ing.


The envi­ron­men­tal friend­li­ness of antifreeze also cre­ates many ques­tions dur­ing use. In the process of mov­ing through the pipes, the anti-freeze may foam, which can pro­voke dif­fi­cul­ties in adjust­ing and bal­anc­ing the sys­tem. The own­er of a house heat­ed with antifreeze should always have a can­is­ter of chem­i­cal in stock in order to quick­ly make up for the defi­cien­cy in the event of a leak.

Application of antifreeze

Before pur­chas­ing a boil­er for heat­ing your home, make sure that it allows the use of this type of antifreeze, oth­er­wise you may void the fac­to­ry war­ran­ty. Con­cen­trat­ed for­mu­la­tions may be mixed with dis­tilled water. When installing the wiring, it is not nec­es­sary to use fit­tings and gal­va­nized pipes, and the heat­ing boil­er must be designed to main­tain a tem­per­a­ture not exceed­ing +70 degrees. A sys­tem based on anti-freeze will require a pow­er­ful pump and a vol­ume tank that is more than twice as large as a water tank.

For the unin­ter­rupt­ed move­ment of antifreeze, pipes of a larg­er diam­e­ter and fair­ly volu­mi­nous radi­a­tors will be required. Auto­mat­ic air vents will not work here — you will need to install Mayevsky man­u­al taps. Only chem­i­cal­ly resis­tant rub­ber can be used as a sealant.


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