Balancing the heating system. We equalize the temperature in the rooms

Win­ter in Rus­sia, as usu­al, comes unex­pect­ed­ly, expos­ing all prob­lems with heat­ing. The most com­mon prob­lem in my prac­tice is the uneven heat­ing of the premis­es.

Where is the problem?

The lion’s share of heat­ing sys­tems is cal­cu­lat­ed “the old fash­ioned way”, accord­ing to the prin­ci­ple “100 watts per m2 of heat­ed area”. Boil­er man­u­fac­tur­ers also con­firm the gen­er­al mis­con­cep­tion. So, for exam­ple, in the descrip­tion of a 20 kW boil­er it is writ­ten that the boil­er is capa­ble of heat­ing a room up to 200 m², although this, to put it mild­ly, is not true. With the same suc­cess, you can spec­i­fy both 10 m² and 400 m².

With this method of choos­ing the pow­er of heat­ing devices, the real heat loss­es of each room are not tak­en into account, and they are very far from the aver­age val­ues. Yes, and the aver­age val­ues, with mod­ern require­ments for insu­la­tion, range from 16 to 40 watts per m2, 100 watts per square meter (approx­i­mate­ly) were lost by old Sovi­et build­ings, most of which are already insu­lat­ed. But this is also the “aver­age tem­per­a­ture in the hos­pi­tal”, and in real­i­ty, cor­ner rooms with a com­pa­ra­ble area lose more heat through two street walls, rooms with panoram­ic win­dows also require more heat per unit area than rooms with ordi­nary win­dows.

As a result, in 8 out of 10 hous­es we have a prob­lem with uneven heat­ing. This is often aggra­vat­ed by the fact that the radi­a­tors are hung on one long cir­cuit, and the tem­per­a­ture of the far radi­a­tors is much low­er than that of the near ones. Bot­tom line — the dif­fer­ence in tem­per­a­ture in dif­fer­ent rooms can be very notice­able. You either have to put up with the uncom­fort­able tem­per­a­ture in some rooms, or heat with a mar­gin, open­ing the win­dows where it’s hot, releas­ing heat into the wind, which costs a lot of mon­ey.

What to do?

In most cas­es, bal­anc­ing the heat­ing sys­tem helps. I’ll make a reser­va­tion right away that there is a tech­ni­cal term “bal­anc­ing the heat­ing sys­tem”, which means hydraulic bal­anc­ing of the sys­tem, that is, equal­iz­ing the pump­ing of the coolant along the cir­cuits accord­ing to the project. I will delib­er­ate­ly use this term, inter­pret­ing it some­what broad­er.

The gen­er­al rec­om­men­da­tion for tun­ing and bal­anc­ing is not to wait for the result imme­di­ate­ly and do not adjust accord­ing to the on / off prin­ci­ple. Heat­ing is a very inert sys­tem; abrupt actions and lack of patience launch this sys­tem into self-oscil­la­tions; it is impos­si­ble to catch the gold­en mean with this approach. Adjust in small incre­ments and patient­ly wait for the desired room to respond to adjust­ment changes, this usu­al­ly takes from half to two days. Your patience will be reward­ed with ther­mal com­fort.

Radi­a­tors with a bot­tom con­nec­tion, as a rule, have a built-in valve that com­bines both adjust­ing and bal­anc­ing. On it, you can reduce the coef­fi­cient of inter­nal resis­tance of the radi­a­tor (KVS) and addi­tion­al­ly screw a ther­mo­sta­t­ic head (ther­mal head) onto the con­trol valve. For the hottest radi­a­tors, we reduce KVS by turn­ing the bal­anc­ing cock, set­ting the resis­tance high­er (the low­er the num­ber, the low­er KVS) than for less hot radi­a­tors, there­by redi­rect­ing the hot coolant to less heat­ed ones.

On cor­rect­ly con­nect­ed sec­tion­al radi­a­tors, a con­trol valve is usu­al­ly placed on the sup­ply line under the ther­mal head, and a bal­anc­ing valve on the return line, which can also be “clamped” on radi­a­tors in warmer rooms. On such taps, as a rule, there is no scale and it is con­ve­nient to adjust them by unscrew­ing them by so many turns from the twist­ed state. How much this “some­thing” is deter­mined exper­i­men­tal­ly, start with 3–4, then either unscrew or twist one or two turns.

Nat­u­ral­ly, a sim­ple instal­la­tion of the ther­mal head on the con­trol valve sug­gests itself, but it is more cor­rect to do this after bal­anc­ing. First­ly, the ther­mal head will close the tap in a warmer room only after the room has warmed up to the set tem­per­a­ture, and the heat will go to the less warm room not imme­di­ate­ly, but much lat­er. Sec­ond­ly, when the ther­mal head clos­es the tap through which the coolant flows at too high a speed, an unpleas­ant crack or knock is heard, and this hap­pens peri­od­i­cal­ly. In addi­tion to knock­ing, at high coolant speeds, radi­a­tors are con­stant­ly noisy. It is not very com­fort­able to sleep next to a knock­ing and noisy bat­tery. The rec­om­mend­ed speed of the coolant in the radi­a­tor con­nec­tion is 0.3 m/s; valves with ther­mal heads are designed to work in just such a flow. The task of bal­anc­ing is to ensure exact­ly this flow rate across all radi­a­tors.

Spinning what we have

If it is not pos­si­ble to install a ther­mal head (the cor­re­spond­ing tap is not mount­ed), then turn what is. There are var­i­ous types and types of con­trol valves on the mar­ket, and if the valve is already installed, it is a sin not to use it for its intend­ed pur­pose.

There is one but! A ball valve is gen­er­al­ly not con­sid­ered to be an adjust­ing valve and should not be used for adjust­ment: only for full clos­ing or open­ing with­out inter­me­di­ate posi­tions. A long stay of the ball valve in an inter­me­di­ate posi­tion con­tributes to its jam­ming and the appear­ance of defects on the ball mir­ror, which sub­se­quent­ly lift up and dis­able the seal.

If there is nothing to turn

If radi­a­tors with­out con­trol valves were used dur­ing the instal­la­tion of the heat­ing sys­tem, then you should not despair. Instead of lim­it­ing the flow of coolant to radi­a­tors in exces­sive­ly warm rooms, you can eas­i­ly lim­it the heat trans­fer of the radi­a­tor. The eas­i­est way is to cov­er it com­plete­ly or par­tial­ly. It is not for noth­ing that radi­a­tors are called “con­vec­tors”: this means that the heat­ing device gives off most of the heat through con­vec­tion — due to the flow of warm air. The air, heat­ing up, expands and rush­es up, then mov­ing in a large cir­cle, grad­u­al­ly cools down, becomes heav­ier and falls down at the oppo­site wall, then returns to the radi­a­tor from below, thus cre­at­ing a closed con­vec­tion flow. The share of con­vec­tion in the total heat trans­fer of most radi­a­tors on the mar­ket is very high — at least 60%. These are almost lim­it­less pos­si­bil­i­ties for reg­u­la­tion. You can reduce the heat trans­fer of any radi­a­tor by sim­ply cov­er­ing it par­tial­ly or com­plete­ly, and in this way equal­ize the tem­per­a­ture in all rooms of the house.

If just cov­er­ing it is not too aes­thet­i­cal­ly pleas­ing, then suit­able pieces of foam rub­ber, sponges for wash­ing dish­es, for exam­ple, can be used. They can gen­tly plug the con­vec­tion chan­nels of the radi­a­tor from below, so they will be com­plete­ly invis­i­ble. There is one caveat here: if you need to halve the con­vec­tion flow, do not close the chan­nels at one half of the radi­a­tor com­plete­ly, it is bet­ter to close them through one in order to pre­vent over­heat­ing of one part of the radi­a­tor com­pared to the oth­er.

View from the bot­tom of the radi­a­tor

Con­vec­tion can only be lim­it­ed at water heat­ing radi­a­tors. In no case do not cov­er or close the chan­nels in elec­tric con­vec­tors, it is very dan­ger­ous!

The pump may be one of the reasons

It will not be super­flu­ous to play with the adjust­ments of the cir­cu­la­tion pump, increase the speed if it is impos­si­ble to bal­ance the sys­tem with cranes or low­er it in case of hydraulic noise. Cir­cu­la­tion pumps built into heat­ing boil­ers usu­al­ly also have flow rate adjust­ment, the instruc­tions for the boil­er say how to change their per­for­mance and this is not dif­fi­cult.

Clean means fast

Be sure to check the coarse fil­ter — “mud”, if one is installed. A clogged fil­ter can great­ly slow down the pump­ing of the coolant, up to a com­plete stop of cir­cu­la­tion.

Applies to everyone

By the way, you need to bal­ance all all heat­ing sys­tems, even very well-cal­cu­lat­ed ones. The fact is that the mar­ket offers radi­a­tors and con­vec­tors with albeit dif­fer­ent, but fixed val­ues ​​of pow­er and hydraulic resis­tance, which nat­u­ral­ly are not equal to the cal­cu­lat­ed and actu­al require­ments. The heater is select­ed with round­ing up to the near­est name­plate pow­er upwards and almost nev­er fits per­fect­ly.

Warm weath­er to your home!
Yours sin­cere­ly, Pro-heat­ing spe­cial­ist, din­jaa.

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