Choosing an uninterruptible power supply for a solid fuel boiler


Even the most cut­ting-edge and high-tech heat­ing tech­nol­o­gy can­not be self-suf­fi­cient. The pres­ence of con­trol sen­sors, con­trol automa­tion, fans and units for extract­ing and forc­ing air mass makes the heat­ing boil­er depen­dent on elec­tric­i­ty. These fea­tures have not bypassed sol­id fuel units, which many are accus­tomed to con­sid­er­ing as com­plete­ly autonomous heat­ing devices. Any fail­ures in the oper­a­tion of the pow­er sup­ply sys­tem have an extreme­ly neg­a­tive impact not only on the effi­cien­cy of the heat­ing sys­tem, but can also cause boil­er equip­ment to fail. This is espe­cial­ly unpleas­ant at the height of win­ter, when the great­est load falls on the autonomous heat­ing sys­tem.

An unin­ter­rupt­ible pow­er sup­ply for a sol­id fuel boil­er will help solve the prob­lem of con­stant pow­er sup­ply to heat­ing units — a device that is equipped today with almost any house­hold equipped with elec­tri­cal appli­ances for var­i­ous pur­pos­es.

What is a UPS? Basic technical requirements for devices

The abbre­vi­a­tion UPS stands for unin­ter­rupt­ible pow­er sup­ply, in Eng­lish UPS. The device is designed to pro­vide for a cer­tain peri­od of time the pow­er sup­ply of any device, device or mech­a­nism for nor­mal oper­a­tion. Unin­ter­rupt­ible is a kind of fuse against unau­tho­rized shut­downs of cen­tral­ized pow­er sup­ply, which can lead to fail­ure of volatile equip­ment and loss of its func­tion­al­i­ty.

An unin­ter­rupt­ible pow­er sup­ply device is equipped with almost any mod­ern tech­nol­o­gy, which in one way or anoth­er is struc­tural­ly con­nect­ed with elec­tric­i­ty. In each indi­vid­ual case, for the autonomous sup­ply of equip­ment with elec­tric­i­ty, its own type of unin­ter­rupt­ible pow­er sup­ply is used, which has cer­tain para­me­ters and spe­cif­ic char­ac­ter­is­tics.

For exam­ple: A UPS for office equip­ment has a cer­tain capac­i­ty and out­put volt­age, while an unin­ter­rupt­ible pow­er sup­ply for home appli­ances, includ­ing heat­ing appli­ances, is designed for oth­er elec­tri­cal para­me­ters. In this case, the device has its own design fea­tures.


Let’s start in order. What dis­tin­guish­es an unin­ter­rupt­ible pow­er sup­ply for a sol­id fuel boil­er, a boil­er, from sim­i­lar devices that are equipped with oth­er elec­tri­cal appli­ances.

1. An unin­ter­rupt­ible pow­er sup­ply for heat­ing units must have out­put volt­age para­me­ters iden­ti­cal to those of elec­tri­cal equip­ment that is equipped with sol­id fuel boil­ers. The sinu­soidal volt­age wave­form is char­ac­ter­is­tic of sole­noid valves, ensures the oper­a­tion of pumps and blow­ers. Only in this case, when the cur­rent in the net­work dis­ap­pears, the elec­tri­cal devices of the heat­ing unit will work in nor­mal mode.

Impor­tant! It is not rec­om­mend­ed to use a UPS designed for com­put­er equip­ment to ensure the oper­a­tion of the boil­er. The rea­son is that such devices do not give a sinu­soidal volt­age, on the con­trary, office unin­ter­rupt­ible pow­er sup­plies give a rec­tan­gu­lar mean­der with zero.

2. An unin­ter­rupt­ible pow­er sup­ply device for sol­id fuel heat­ing units must ensure a suf­fi­cient­ly long oper­a­tion of heat­ing equip­ment. In oth­er words, the bat­tery capac­i­ty must be sig­nif­i­cant in order to ensure the autonomous oper­a­tion of boil­er equip­ment dur­ing a pow­er out­age. Office devices are designed for a max­i­mum of 10–15 min­utes of pow­er, cal­cu­lat­ed only to bring com­put­er equip­ment out of oper­a­tion with­out fail­ure.

3. Any heat­ing boil­er, sol­id fuel devices are no excep­tion, are sen­si­tive to volt­age drops. When turned on, the unin­ter­rupt­ible pow­er sup­ply must receive a suf­fi­cient amount of elec­tric­i­ty from the bat­ter­ies, suf­fi­cient to pro­vide volt­age with the same phase as in a cen­tral­ized net­work.

4. In the event of pow­er out­ages and out­ages, the tran­si­tion of the sol­id fuel boil­er to pow­er sup­ply from the UPS should not exceed 10 mil­lisec­onds.

Types of uninterruptible power supplies for solid fuel heating equipment


Any autonomous heat­ing sys­tem is equipped with an unin­ter­rupt­ible pow­er sup­ply. Depend­ing on the type and type of boil­er equip­ment, an unin­ter­rupt­ible pow­er sup­ply of the appro­pri­ate type is installed. To date, in prac­ti­cal terms, three types of UPS are used:

  • off-line devices;
  • devices Line — inter­ac­tive;
  • dou­ble con­vert­ers, On-line sys­tems.

Each mod­el of the device dif­fers in its design and prin­ci­ple of oper­a­tion. Let’s con­sid­er in more detail.
Off-line unin­ter­rupt­ible devices are the most com­mon devices. They have a sim­ple design and afford­able cost. The work is based on the fol­low­ing prin­ci­ple:

  • pow­er fail­ure in the net­work, volt­age drops trig­ger the UPS-bat­tery cir­cuit. The volt­age that appears returns the device to nor­mal mode — pow­er from the mains. The time for switch­ing the device to bat­tery pow­er and vice ver­sa is no more than 15 mil­lisec­onds.

The prod­uct con­sists of tra­di­tion­al ele­ments: an invert­er that con­verts the direct cur­rent in the bat­tery into elec­tric­i­ty with a volt­age of 220V. Off-line mod­els work from the mains with a volt­age of 170–270V. The main dif­fer­ence of this type is that they do not have a volt­age sta­bi­liz­er, so the out­put volt­age of such unin­ter­rupt­ible pow­er sup­plies is equiv­a­lent to the mains volt­age.

On a note: In case of unsta­ble oper­a­tion of the pow­er grid, the unin­ter­rupt­ible switch con­stant­ly switch­es either to the bat­tery or to the cen­tral­ized pow­er sup­ply net­work. This mode leads to a rapid reduc­tion in the life of the device.

Anoth­er type of UPS used in prac­tice is the inter­ac­tive unin­ter­rupt­ible pow­er sup­ply. These devices are equip­ment that occu­pies an aver­age niche, both in terms of func­tion­al­i­ty and in terms of cost. The prin­ci­ple of oper­a­tion of inter­ac­tive autonomous pow­er sup­plies is sim­i­lar to that of off-line invert­ers. The only dif­fer­ence is the pres­ence of a volt­age sta­bi­liz­er. Due to their design, such devices are more reli­able and safe to use. Each mod­el in this case is designed to inter­act with the cen­tral pow­er sup­ply net­work 170–270V.

The last, third type of unin­ter­rupt­ible pow­er sup­plies is a device oper­at­ing in live time, on-line. In these devices, there are prac­ti­cal­ly no dis­ad­van­tages inher­ent in the oth­er two types of UPS. The main high­light of these devices is as fol­lows:

  • The UPS con­verts the input AC to DC volt­age in real time, regard­less of its para­me­ters and char­ac­ter­is­tics. In the future, the direct cur­rent is already con­vert­ed into a sta­bi­lized, alter­nat­ing volt­age.

Such mod­els have an unde­ni­able advan­tage, besides, on-line UPSs work effec­tive­ly in tan­dem with gen­er­a­tor sets. This fea­ture is very rel­e­vant in sit­u­a­tions where there is no cen­tral­ized pow­er sup­ply for a long time, the oper­a­tion of elec­tri­cal appli­ances depends on the func­tion­al­i­ty of autonomous mini-pow­er plants.

From a tech­no­log­i­cal point of view, the design of an on-line UPS is quite com­plex. Accord­ing­ly, these prod­ucts are expen­sive. The expe­di­en­cy of using such equip­ment is jus­ti­fied in those con­di­tions when boil­er mod­els that are sen­si­tive to pow­er surges are installed.

Based on the fore­go­ing, cer­tain con­clu­sions can be drawn. Most often, for the nor­mal oper­a­tion of heat­ing boil­ers oper­at­ing on coal, wood and oth­er types of sol­id fuels, it is enough to acquire an active unin­ter­rupt­ible pow­er sup­ply or an off-line device. When in a coun­try house or in the pri­vate sec­tor, due to fre­quent pow­er out­ages, the main load falls on diesel gen­er­a­tors, the best option would be to buy an on-line unin­ter­rupt­ible pow­er sup­ply.

The choice of an uninterruptible What to look out for

The choice of an unin­ter­rupt­ible pow­er sup­ply for sol­id fuel boil­ers is influ­enced by a vari­ety of fac­tors. First of all, it is nec­es­sary to deter­mine the pow­er of the heat­ing unit, the func­tion­al­i­ty of the heat­ing sys­tem, which will be pro­vid­ed if nec­es­sary by the UPS.

In many ways, not only the type of unin­ter­rupt­ible pow­er sup­ply, but also the type of bat­tery depends on the pow­er of the boil­er. The capac­i­ty of the bat­tery deter­mines the dura­tion of the oper­a­tion of the unin­ter­rupt­ible pow­er sup­ply. The table shows the para­me­ters of the equip­ment cor­re­spond­ing to a par­tic­u­lar heat­ing device.

boil­er pow­er,


fifty 100 150 200 300 400 500
Bat­tery capac­i­ty (bat­tery) Am/h
65 6.8 6.8 3.9 2.2 1.5 1.1 0.7
100 25.7 12.2 7.2 5.4 3.1 1.8 1.4
150 37.9 18.1 12.1 8.1 5.4 3.4 2.1
250 49.2 24.6 16.0 12.0 7.3 5.5 3.8

The choice of the type of UPS is influ­enced not only by the pow­er of the heat­ing device, but by the num­ber of addi­tion­al units pow­ered by elec­tric­i­ty. This should include fans, heat­ing sys­tem pumps, con­trol devices, alarms and adjust­ments.

The opti­mal choice of UPS also depends on the qual­i­ty of the cen­tral­ized pow­er sup­ply, which includes the fre­quen­cy of out­ages, the dura­tion of out­ages, and the range of volt­age drops in the net­work.

Impor­tant! When ana­lyz­ing the capa­bil­i­ties of a UPS, do not for­get about the induc­tive load. Mech­a­nisms and elec­tri­cal appli­ances that are installed on the equip­ment of heat­ing equip­ment give a sig­nif­i­cant induc­tion load to the inter­nal elec­tri­cal net­work. When fans or cir­cu­la­tion pumps are start­ed, the load in the net­work increas­es by 3–6 times. Mod­ern mod­els of unin­ter­rupt­ible pow­er sup­plies are able to with­stand short-term over­loads, how­ev­er, the best option would be to buy a UPS with a pow­er reserve of 25–30%.



Ulti­mate­ly, when buy­ing a device, you should pay atten­tion to its auton­o­my. The dura­tion of the UPS is direct­ly depen­dent on the capac­i­ty of the bat­tery. Accord­ing­ly, the larg­er the bat­tery capac­i­ty, the high­er the cost of the device. As a rule, two types of sta­tion­ary bat­ter­ies are used to oper­ate the UPS in an autonomous heat­ing sys­tem: AGM or GEL. These are devices made on the basis of lead-acid cells.

GEL bat­ter­ies have a large capac­i­ty and are designed for heavy loads. In addi­tion, this type of bat­tery has a sig­nif­i­cant resource of charge and dis­charge cycles.

On a note: for the oper­a­tion of sol­id fuel boil­ers (any heat­ing devices), car bat­ter­ies should not be used. The rea­son is the chem­i­cal com­po­si­tion of the oxi­diz­ing agent. Using a UPS to oper­ate an autonomous boil­er involves installing the device togeth­er with the bat­tery in the boil­er room. The evap­o­ra­tion of hydro­gen dur­ing the oper­a­tion of heat­ing equip­ment can even­tu­al­ly lead to the for­ma­tion of an explo­sive hydro­gen-oxy­gen mix­ture.

The pro­posed types of bat­ter­ies for the oper­a­tion of unin­ter­rupt­ible pow­er sup­plies have an unde­ni­able advan­tage — they do not need con­stant main­te­nance.

The video shows how to select an unin­ter­rupt­ible pow­er sup­ply for sol­id fuel boil­ers.


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