Wood boilers with 25-100kW output

LUK boilers are for heating terraced houses, apartment blocks, production and municipal buildings mainly with logs; however, by adding a burner, it is possible to heat with pellets, wood chips or grain. Depending on the boiler’s model, the heated house surface remains between 100-1200 m².


  • operating reliability: boiler’s well-thought structure ensures a lengthy durability
  • universality: fuel can be logs, coal. By adding a burner, wood chips, grain leftovers, wood granules, pellets, wood and peat briquette, sawdust and wood shavings can be used for fuel.
  • quality: the boiler is made of boiler steel and according to a standard EVS EN303-5:2012
  • effectiveness: three fire tubes ensure high efficiency and low smoke temperature
  • comfort: large service hatches and spacious firebox ensures comfortable heating and maintenance
  • tailor-made product according to a customer’s requests
  • credibility: we have been producing boilers for over 20 years
  • maintenance: we guarantee that our products will operate for a long period
  • spare parts: immediate availability of all spare parts


When heated with logs, it is recommended to install an accumulation tank to the heating system. The accumulation tank enables to prolong the heating cycle and maintain more even temperature in the rooms being heated.

Additionally, it is possible to install a solid fuel burner, whether on the right/left side or at the front door. In case of a pellet burner, we recommend to install the burner on the burner’s door. By ordering a boiler with a side burner hole, it is possible to use wood chips, grain, grain leftovers, wood shavings, peat briquette for a fuel.

The boiler set includes a thermo-manometer, pressure relief valve, hook, broom. Ash isolation system and smoke turbulators and pneumatic cleaning system for convective parts are available as add-ons.

high efficiency

The boiler has three horizontal fire tubes that ensure high efficiency and fast heat transfer. Cleaning the boiler’s firebox and convective parts is easy, comfortable and takes very little time. The boiler has large service hatches. By notifying us in advance, it is possible to change the handedness.

The boiler is made of quality boiler steel according to the standard of manually and automatically heated solid fuel boilers EVS-EN 303-5:2012. The horizontal smoke tubes of the boiler are made of Ø 76 mm pulled steel pipes and the firebox is made of 8 mm steel sheet. The boilers have been tested in the combustion test at Tallinn University of Technology and Estonian University of Life Sciences.

1. Cleaning hatch
2. Secondary air regulator
3. Boiler door – filling hatch
4. Primary air regulator

5. Ash hatch
6. Chimney damper
7. Flue gas duct
8. Rear cleaning hatch

9. Insulation
10. Drain 1/2”
11. Return inlet
12. Flow outlet

13. Safety valve 3/4”
14. Primary air regulator slot 3/4”
15. Water jacket
16. Combustion chamber

Nominal heat output kW 25 35 50 80 100
Efficiency with wood logs % 83
Main fuels
Wood logs, wood and peat briquettes
Efficiency with wood pellets % 90
Alternative fuels
Wood pellets, wood chips, grain and grain residues, sawdust, planer shavings
Boiler heating surface 1,8 2,3 3,3 5,4 6,7
Combustion chamber length mm 540 590 590 840 840
Combustion chamber volume 0,08 0,12 0,16 0,30 0,44
Maximum operating water pressure bar 2,5
Test pressure bar 3,75
Minimum return water temperature ºC 60
Maximum operating water temperature ºC 95
Water volume of boiler liiter 110 130 170 270 380
Flow and return pipe connections 1 1/4 1 1/2 1 1/2 2 2
Boiler weight kg 280 335 440 730 950
Building heated area ≤150 ≤220 ≤350 600 1000
Length A mm 1120 1170 1170 1420 1470
Width B mm 530 680 680 750 860
Height C mm 1160 1210 1520 1520 1840
Flue gas outlet height D mm 930 965 1265 1265 1560
Flue gas outlet diameter mm Ø154 Ø174 Ø194 Ø 244 Ø 294
Minimum chimney draught Pa 25
Recommended chimney cross-section cm² 400 600 600 800 900
Recommended chimney height m 6-10 10-14
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