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Our flagship product
- a new version available since 2010!

The smallest pellet boiler in Poland! Equipped with OMS (operating monitoring system).
Ecodesign 2020 A+ Energy Class OMS - Monitoring and control system OMS System Patent 5 Class
A1 Pellets A1 Pellets/Oat
A1 Pellets A1 Pellets/Oat
This device is subsidised in these countries:

Poland Slovakia Bulgaria
Mini Bio NE
10 kW 15 kW 20 kW
Mini Bio NE See product
  • Passive house Passive house
  • Single-family house Single-family house
  • Multi-family house Multi-family house
  • Small farm Small farm

Designed for heating buildings without boiler room or with small boiler room. Reduced overall dimensions with a storage hopper installed on the heat exchanger - a solution used for the first time by Kostrzewa in 2009 in our flagship product Mini Bio boiler and well-received by our clients. A new version with improved comfort, cleanliness and a guaranteed energy-efficiency.


The OMS (Operating and Monitoring System) monitors fuel level and ash content. User is informed in advance that the fuel storage must be refilled or the ash pan requires cleaning.


Reduced fuel consumption with Mini Bio. A unique design and advanced ceramic inserts for over 90% efficiency.



High quality steel and the highest quality components guarantee many years of failure free operation. All new models are thoroughly tested for many months before marketing. All our boilers are individually tested for durability at min. 4 bar - a feature hardly ever found elsewhere.



We maintain an extensive service network. Over 200 qualified service engineers provide warranty and post-warranty services in Poland and abroad.



All boiler and central heating system functions can be remotely monitored using a PC or a smartphone (optional).



Even the best boiler isn’t enough. We offer complete boiler room and heating system solutions. We offer advanced solutions including pellet storage, pneumatic fuel feeding, cascade automation, weather compensated CH system control, DHW and buffer tank control, return protection, fuel and ash sensors, heat pump, solar panel and gas boiler control.

Tests and certificates

Our boilers are tested by an accredited testing facility - a member of the international Association of Accreditation..


The test results show that KOSTRZEWA products meet the emission requirements laid down in the Ecodesign Directive and guarantee user safety.


All boiler types undergo over 20 different tests including:


  • Boiler pressure test at 4 bar
  • Energy-efficiency and emission tests at 10%, 11% and 13% fuel oxygenation
  • Energy consumption test in operation and standby mode
  • Operational test in a closed loop system without auxiliary safety devices
    Our boilers are included in the list of devices qualifying for a subsidy in many EU countries.


We recommend




compact, silent and energy-efficient.


automatic burner start-up, automatic burner modulation with 2nd Generation Fuzzy Logic, flame control with a photocell, low thermal inertia during start-up and shutdown, low power input, burner temperature control for highest safety, three-stage start-up to prevent gas explosions, AUTOSTART after power loss - the current settings are stored, separate primary and secondary air ducts for reduced CO emission (emission levels similar to gas and oil burners), automatic cleaning function - automatic slag removal from the grate (not available in the gravity fed models), oats - burner design allows use of oats as a fuel, ceramic insert - reduced emission and higher efficiency.

  OMS (operating monitoring system)

OMS (operating monitoring system)

Operating and monitoring system for solid fuel boilers. Our boilers are fitted with a system monitoring fuel level in the storage tank and the amount of ash in the ash pan to guarantee convenient and comfortable operation. In many boilers without a similar system available on the market user must remember to refill fuel and remove ash regularly. The system, developed by KOSTRZEWA, measures and notifies the user in advance on required actions (fuel refilling or ash removal). Notifications are displayed on a boiler controller screen and a room temperature controller screen. Our solution is patent protected.



An advanced device monitoring the combustion process in the boiler and the pellet burner.


fuel feeding from the storage tank, fuel feeder, pressure blower, igniter, CH pump, DHW pump, fuel level sensor, boiler/buffer tank pump, heating circuit mixing valve - module B (optional), recirculation pump - module B (optional), buffer tank - module B (optional), two auxiliary mixing valves - module B (optional) and two auxiliary mixing valves - module C (optional).


external temperature sensor, CH sensor, DHW sensor, colour ecoSTER TOUCH control panel with remote boiler control, programmable wireless 7-day thermostat, programmable wired 7-day thermostat, adjustable temperature sensor, EcoLAMBDA oxygen sensor, auxiliary extension module (B, C) and EcoNET internet module.




A virtually maintenance-free pneumatic device feeding pellet at a large distance from the storage area directly to the boiler including multiple sensors for a fully automatic operation.  If MINIMUM level is detected in the buffer tank, it is immediately refilled to the MAXIMUM level. The device can also be timer programmed, i.e. the buffer tank will be refilled to the MAXIMUM level at a pre-set date and time.

Mini Bio NE
Object power selection
Boiler power Heating surface
m2 m3
10 kW 50-200 125-500
15 kW 85-200 212-500
20 kW 100-300 250-750
Surface is provided at ceiling height of 2.5 m.
10 kW 15 kW 20 kW
Flue draught mbar 0,15-0,20 0,15-0,20 0,15-0,20
Water capacity l 47 90 90
Maximum working pressure bar 2 2 2
Test pressure bar 4 4 4
Flue gas temperature at rated output °C 99,2 95,4 111,2
Flue gas mass flow at minimum output °C 64,9 75,5 74,8
Flue gas mass flow at rated output kg/s 0,0063 0,00929 0,01158
Flue gas mass flow at minimum output kg/s 0,0032 0,00468 0,00514
Flue connector diameter mm 127 159 159
Flow resistance at 10 K mbar 11 16,4 21,8
Flow resistance at 20 K mbar 3,1 4,6 6,1
Rated heat output kW 10 15 20
Heat output range kW 3-10 5-15 6-20
Efficiency at rated output % 92,8 93 92,8
Efficiency at minimum output % 89,3 90 91
Boiler class as per EN 303-5 5 5 5
Combustion time at rated output
(fuel calorific value: 17,280 kJ/kg)
h 62 43 32
Temperature controller settings range °C 50-80 50-80 50-80
Minimum water return temperature °C 45 45 45
Fuel type Class Sawdust granulate (pellet made according to EN ISO 17225-2 class A1)
Test fuel used in the certification procedure - A1.
Also compatible with A1 class pellet/ oat mix.
Storage hopper capacity l 220 230 230
Hopper dimensions mm 550x550 655x655 655x655
Power supply V / Hz / A 230 / 50 / 2 230 / 50 / 2 230 / 50 / 2
Power input at rated output W 61 87 112
Pobór mocy elektrycznej dla mocy minimalnej W 17 25 33
Power input in STANDBY mode W 2 2 2
Maximum power input W 492 492 492
Maximum noise level dB 52 52 52

PELLET is a processed waste timber compressed under high pressure without use of any bonding agents.


PELLET CLASSES TO PN-EN ISO 17225-2:2014-07:

A1 - ash content ≤0.7% Premium quality product

A2 - ash content ≤1.2%

B - ash content ≤2%


PELLET - eco-friendly, high-energy clean fuel!

Ceramics is everywhere - the combustion chamber, the heat exchanger and the burner are coated with advanced ceramics to improve the combustion process and efficiency and to reduce the emission. During operation, the ceramics heats up to over 1,000°C to improve the biomass combustion efficiency.


Flue gas vortex generators retain energy inside the boiler.


Product data sheet 90.19 KB
Mini Bio NE 15 Certificate 691.26 KB
Mini Bio NE 20 Certificate 344.06 KB
Mini Bio NE 10 Certificate 397.22 KB
Declaration of Conformity 217.58 KB

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