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.

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 has three horizontal fi re 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 previously notifying the company Rapla Metall, 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. The boiler set includes a pressure relief valve, hook, broom. Ash isolation system and smoke turbulators and pneumatic cleaning system for convective parts are available as add-ons.

Operating description of the boiler

All LUK- type boilers transfer the heat generated in the combustion chamber by convection to the boiler water through the steel walls of the boiler’s combustion chamber and flue gas pipes. Hot flue gases travel from the combustion chamber to the upper flue gas pipes passing through the lower flue gas pipes and the cleaning hatch slot and ending up in the flue gas duct, thus generating three flue gas passages.

The optimal burning control is achieved by setting the primary and secondary air and changing the amount of fuel. The quality of burning can be visually assessed or measured by means of a gas analyser.

Used fuels

LUK- type boilers are intended for burning various solid fuels. The nominal power of the boilers is estimated with a solid fuel with humidity level below 30%. The boilers are foremost intended for burning firewood, but they are also suitable for wood clips, briquette an peat.

BOILER MODEL	UNIT	LUK-25	LUK-35	LUK-50	LUK-80	LUK-100
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	m²	1,8	2,3	3,3	5,4	6,7
Combustion chamber length	mm	540	590	590	840	840
Combustion chamber volume	m³	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	m²	≤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