instruction for beginners and experts

Expan­zomat, or, as it is com­mon­ly called, an expan­sion tank, is the most impor­tant ele­ment of any autonomous heat­ing sys­tem (CO). The pur­pose of this device is to com­pen­sate for ther­mal expan­sion and replen­ish minor coolant leaks. If the vol­ume of this con­tain­er is too large, it will be almost impos­si­ble to cre­ate the nec­es­sary pres­sure in CO. Too small a tank may not accept excess coolant. That is why it is so impor­tant to choose the right vol­ume of the expan­sion tank for heat­ing. The meth­ods for cal­cu­lat­ing the expan­sion mat will be dis­cussed in this pub­li­ca­tion.

The final result of com­pu­ta­tion­al oper­a­tions is: deter­mi­na­tion of the vol­ume of the tank; the min­i­mum diam­e­ter of the sup­ply pipe; the val­ue of the ini­tial pres­sure in the device and the work­ing pres­sure in the sys­tem.

Today, there are three main meth­ods for cal­cu­lat­ing the vol­ume of an expan­sion tank for heat­ing: cal­cu­la­tors post­ed on spe­cial­ized sites, soft­ware and self-cal­cu­la­tion using for­mu­las. When cal­cu­lat­ing using online cal­cu­la­tors, some­times a val­ue with a high error is obtained. Spe­cial­ized soft­ware, as a rule, is dis­trib­uted on a paid basis, which is quite expen­sive. Next, con­sid­er the method of self-cal­cu­la­tion.

Expanzomat calculation formula

Volume dependent on temperatureAt first glance, it is dif­fi­cult and takes a lot of time. In fact, any­one who knows the mul­ti­pli­ca­tion table is able to per­form these cal­cu­la­tions.

Vbaka = (Vsyst * k) / N

Vsyst is the vol­ume of total CO.
Kis the tem­per­a­ture coef­fi­cient of liq­uid in CO
N — the val­ue of the effi­cien­cy of the expander.

Firstwhat you need to do is to cal­cu­late the vol­ume of coolant in the sys­tem. You can do this:

  • pump­ing it with water (gly­col antifreeze), then drain­ing and mea­sur­ing the vol­ume of liq­uid (using a flow meter or mea­sur­ing con­tain­er).
  • by cal­cu­lat­ing the vol­ume your­self.

The first method requires a lot of time and effort. The sec­ond method does not require labor. The total vol­ume of CO is cal­cu­lat­ed based on the pow­er of the heat gen­er­a­tor.

Impor­tant! For 1 kW of pow­er of the boil­er plant, an expander with a capac­i­ty of 15 liters is required.

For exam­ple: the pow­er of the boil­er unit in CO is 30 kW. Based on this, the total vol­ume of the sys­tem will be: 30 kW x 15 liters. u003d 450 l. So: the first val­ue for cal­cu­lat­ing the vol­ume of the expan­sion tank for heat­ing (Vsyst) u003d 450 l.

Sec­ond mean­ing (K) is a con­stant val­ue. Fig­ure her out can be found in the ref­er­ence lit­er­a­ture.

Impor­tant! For water, the con­stant is 4%, for 10% eth­yl­ene gly­col, 4.4%; for 20% 4.8%; The val­ue is valid for CO, in which the coolant is heat­ed up to 95°C.

The table shows the depen­dence of the ther­mal expan­sion of gly­col antifreezes on the heat­ing tem­per­a­ture and the per­cent­age of the active sub­stance in the aque­ous solu­tion.The dependence of the thermal expansion of glycol antifreezes on the heating temperature

Third val­ue (N), most often, good man­u­fac­tur­ers are indi­cat­ed in the doc­u­ments for the espan­zomat. If there is no data, then we will cal­cu­late inde­pen­dent­ly accord­ing to the for­mu­la:

N =(Pmax- Pn) / (Pmax + 1)

Pmax is the val­ue of the max­i­mum allow­able pres­sure in CO.

Impor­tant! In autonomous CO of apart­ments and pri­vate hous­es, the upper pres­sure lim­its are in the range of 2.5–3 kg / cm2. In order to find out the exact max­i­mum allow­able pres­sure, you need to look at the set­ting of the safe­ty valve in the safe­ty group.

Pn is the ini­tial pres­sure in the tank. The cal­cu­la­tion is based on 0.5 kg/cm2 for every 5m height of CO.

For exam­ple: coolant — water; the height of the sys­tem is not more than 5m; allow­able pres­sure 3 kg/cm2 then:

N = (3 — 0.5) / (3 + 0.5) = 0.71

Now, hav­ing the ini­tial data in hand, you can start the cal­cu­la­tions.

K = (450l x 0.04) / 0.71 = 25.35l

Tip: when cal­cu­lat­ing the vol­ume of the expan­sion mat in CO with water as a heat car­ri­er, increase the cal­cu­lat­ed val­ues ​​by 15–20%. If antifreeze will cir­cu­late in the CO, then increase the cal­cu­lat­ed expan­sion tank capac­i­ty by 50%.

Rules for choosing an expander

Most devel­op­ers, espe­cial­ly those who are faced with the cre­ation of autonomous COs for the first time, are inter­est­ed in the ques­tion: “How to choose an expan­sion tank for a heat­ing sys­tem?”

Com­pe­tent selec­tion of this device can be divid­ed into four stages. The algo­rithm is the fol­low­ing:

  • Deter­mine the required type of expander. Every­thing is sim­ple here: for open CO — an open tank; for closed — a mem­brane (bal­loon) tank.
  • Cal­cu­late the required tank vol­ume.
  • Pay atten­tion to the qual­i­ty of the prod­uct. Impor­tant points are: the qual­i­ty of the body met­al and col­or, which should pro­tect the device from cor­ro­sion; the pres­ence of an adjustable blast valve; mem­brane char­ac­ter­is­tics and the pres­ence of an inter­na­tion­al qual­i­ty cer­tifi­cate.

    Tip: Today, tanks with a replace­able mem­brane are avail­able in a wide range. If funds allow, we rec­om­mend choos­ing just such a mod­el.

  • Decide on the design, size and shape of the device.The difference in shapes and sizes of expansion tanks

On the Euro­pean mar­ket of cli­mat­ic equip­ment there are con­tain­ers of var­i­ous vol­umes, hor­i­zon­tal or ver­ti­cal ori­en­ta­tion, designed for dif­fer­ent work­ing and max­i­mum pres­sures. Pay atten­tion to the col­or of the device: blue — for the water sys­tem; red — for CO.

And the last. The selec­tion of an expan­sion tank for heat­ing is a rather respon­si­ble process, on which the sta­bil­i­ty of the CO oper­a­tion depends. Entrust the choice to pro­fes­sion­als.


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