When firewood is loaded, a single load can burn up to 30 hours.

A single load of sawdust briquettes can burn up to 4 days.

Solid fuel: firewood, timber waste, sawdust briquettes, wood chips.


Combustion duration of solid fuel load depends on its quality of fuel, outdoor and indoor temperature, thermal resistance, and other factors.

Recommended moisture ≤30%*



  • 1. air damper
  • 2. bi-thermal draught regulator
  • 3. supporting stick
  • 4. air heating chamber
  • 5. smoke extraction flue
  • 6. Switch damper (U – in universal boilers)
  • 7. Telescopic air injection pipe
  • 8. solid fuel loading doors
  • 9. air distributor with a combustion chamber stabilizer
  • 10. solid fuel
  • 11. ash removal doors
  • 12. lifting rope with a ring
  • 13. hook
  • 14. Flow pipe
  • 15. return pipe
  • 16. thermometer tip
  • 17. 1,5 bars pressure safety valve tip
  • 18. Bottom
  • 19. grate (U – in universal and biomass boilers)



Boiler model S7 BIO
Power (kW)* 7
Heating area ( m²)** 20-70
Fuel capacity (dm³) 90
Maximum amount of firewood (kg) 15
Maximum amount of wood pellets (kg) 50
Maximum amount of briquettes (kg) 20
Maximum amount of coal (kg)
Burning time of wood on a minimum time mode (hr)  28
On maximum mode ***  5,6
Burning time of briquettes on minimum mode (hr) 50
On maximum mode *** 10
Burning time of wood pellets on minimum mode (hr) 72
On maximum mode *** 14
Burning time of coal on minimum mode (hr)
On maximum mode ***
Firewood length (cm) iki 35
Amount of water in the boiler (l) 15
Efficiency (%) 86,3
Water boiler pressure maximum (bar) 2,0
Pressure safety valve (bar) 1,5
Chimney Draught (Pa) 10-20
Flow of heated water (l / h) 200
Water temperature in the boiler (° C) 85
Minimal area of ​​chimney flue (cm²) 150
Chimney diameter (mm) 160
Distance between ground and chimney (mm) 961
Height (mm) 1330
Depth (mm) 450
Weight (kg) 129,6

*Power depends on the quality of fuel, heating needs for house, chimney draught.

** The boiler output is chosen according to a heating area. E.g., solid fuel is burning the whole day (20-24 hours) in the solid fuel boiler Stropuva S20 in the 200 m² building whereas the firewood is burning almost 2 days (35-40 hours) in the solid fuel boiler Stropuva S40 in the house of the same area. A solid fuel boiler Stropuva S10 also can be used but the building will warms up slowly and the boiler would have to be loaded 2-3 times a day.

*** Combustion duration depends on the quality of fuel, outdoor and indoor temperature, thermal resistance, the power of boiler, and the way recommendations of user guide are complied (boiler installation, heated water stream, water temperature maintenance).

Mounting information: