B² flex

The external shape of the B² flex follows the technical requirements of its function. This is what gives it its time- lessly fashionable, simple outline. The B² flex’s compact dimensions make it fit even in small spaces. Both front versions can be freely combined with side-covers of steel, hand-crafted ceramic or natural stone. This allows a significant part of the B² flex’s appearance to be defined by you.

The basic B² flex model with a height of only 1.10 metres standing on stable steel feet appears very discreet but has everything a high-quality stove needs. The B² flex BOX version (1.25 metres high) allows easy storage of firewood under the combustion chamber. If preferred, the firewood box can be enclosed with a precisely fitting steel door.

The B² flex can be approved for a tested nominal heat output (NHO) of 5 kW, or if the version with the ChimCat® catalytic converter is chosen a NHO of 3.6 kW to 6 kW. With ChimCat® the B² flex reaches an efficiency factor of up to 84 percent, without ChimCat® even up to 88 percent.



  • Balance between convection and radiation heat
  • Nominal heat output of 5 kW without catalytic converter and 9 to 6 kW with catalytic converter
  • Highly economical through extremely high efficiency factors of up to 88 percent
  • Derzeit nur noch mit abgerundeter Front erhältlich
  • Choice between “Standard” model on steel feet, and “Box” model with firewood box and, if requested with fitted steel door
  • Seitenverkleidung in Stahl (für BOX) und nur Keramik (auf Füßen)
  • Modest space requirements through compact dimensions
  • Flue connection either at the rear or on the top
  • Four height adjusters for levelling the stove on uneven floors


  • Self-closing and -locking door with large viewing window
  • Effective integrated window washing system
  • Intuitive control of the fire using a precisely coordinated inflow of air
  • Extremely solid combustion chamber of 4 mm thick, edged steel
  • Firebox lining made of high-quality vermiculite and special robust fireclay
  • Potential wear parts, in part of heat-resistant premium steel, can be replaced even after years if necessary
  • Warranty extension (total 5 years) to the stove body on registering the product
  • Comprehensive service offering by the Bullerjan specialist dealers or Bullerjan customer service


  • Optional complete independence of room air (Raumluftunabhängig RLU) in accordance with DIBt at no extra cost, making it principally suitable for low energy and passive Please always clarify conditions in advance with your chimney sweep.
  • Optional fitting with ChimCat® catalytic converter (can also be easily retrofitted) extends the clean output range from 5 kW to 9 to 6 kW. This in combination with significantly reduced emissions levels make this option the right choice for the environment.
ModellB² flex model 2017
catalytic converter
B² flex model 2017
with catalytic converter
B² flex
with catalytic converter
B² flex BOX Modell 2017
Performance5,0 kW3,9 kW6,0 kWdto.
Depth with straight front41,10 cm41,10 cm41,10 cm41,10 cm
Depth with rounded front35,75 cm35,75 cm35,75 cm35,75 cm
Width41,8 cm41,8 cm41,8 cm41,8 cm
Height110,5 cm110,5 cm110,5 cm125,5 cm
Weight107,0 kg107,0 kg107,0 kg130,0 kg
Weight with equipment
126,6 kg126,6 kg126,6 kg163,8 kg
Weight with equipment
128,6 kg128,6 kg128,6 kg166,8 kg
Weight with equipment
135,0 kg135,0 kg135,0 kg176,4 kg
Depth of combustion chamber25,5 cm25,5 cm25,5 cm25,5 cm
Exhaust gas nozzleØ 15 cmØ 15 cmØ 15 cmØ 15 cm
Air supply nozzleØ 10 cmØ 10 cmØ 10 cmØ 10 cm
Height centre exhaust
gas nozzle
100,0 cm100,0 cm100,0 cm113,5 cm
Height centre air
supply nozzle
38 cm38 cm38 cm51,5 cm
Exhaus gas mass flow rate
(nominal heat output)
4,11 g/s4,66 g/s5,13 g/sdto.
Delivery pressure12 Pa12 Pa12 Padto.
Mean exhaust gas temperature223 °C252 °C277 °Cdto.
CO content
(13 % O 2 )
0,094 Vol.-%0,034 Vol.-%0,021 Vol.-%dto.
CO content
(13 % O 2 )
1172,9 mg/m³419,9 mg/m³260,0 mg/m³dto.
(13 % O 2 )
36,9 mg/m³29,9 mg/m³28,9 mg/m³dto.
Efficiency88 %84 %86 %dto.