Combi gasyfying boilers PYROSTAR DUO for pelelts, wood and wood briquets are ecological heatings boilers controlled with modern electronic regulator with microprocessor, Lambda control and servomotor,  that verifies all requests on unassuming attendance and high comfort, as well as control of whole central heating systems and heating of sanitary warm water.

The safety of the boiler running is secured with 2 emergency thermostats and with integrated security heat exchanger against overheating, what is the main condition for installing the boilers in heating systems with circulating pump.

Boilers PYROSTAR DUO verify the limits according EN 303-5, as well as the limits for the german 1.BlmSchV, for Swiss and Austria. Boilers PYROSTAR DUO 25 and PYROSTAR DUO 30 verify also the BAFA limits.


Construction of ceramic combustion chamber in rear part and fuel feed in front part of boiler PYROSTAR DUO protect the boiler against flue condensation, what increase its lifetime and simplifies its cleaning and maintenance.


Boilers MODRATHERM PYROSTAR DUO are used for pellets, wood and wood briquetts burning with the maximum wood lenght of 550 mm. According to the type it is possible to burn wood with following lenght :

                   Type                                                                 wood lenght

PYROSTAR DUO 18, PYROSTAR DUO 25                     400 mm
PYROSTAR DUO 30, PYROSTAR DUO 50                     550 mm


The wood firing runs by high temperatures on the principle of gasyfying. The boiler body is manufactured of a high-quality steel plate with the thikness of 5mm (plates which are in touch with fire and water) and 3mm (plates which are in touch only with water). A part of the water circly are also 3 or 4 water lamellas in the upper part of boiler body. The insulation cover is made from steel plate with the thikness of 0,8mm, covered with a pulver colour. The thermal insulation is built with with mineral cotton.


Primary air is supplied to the boiler through a flap on the left bottom side of the boiler on the front side of the boiler. The primary air enters the loading area through wholes of the bricks from concrete firebeton on the sides of the boilers ant enters the jet through the glow.  Secondary air is supplied to the chamber nozzle through a flap on the left bottom side on the front side of the boiler through channels in the firebeton combustion chamber. The secondary air is controlled with a servomotor Belimo.

In the bottom part of the feeding place are ceramic blocks and massive segmental cast iron grate filled with ceramics blocks. 

The segmented ceramic heating chamber is in the rear part of the boiler and reaches up to the water lamellas. The haeting chamber is made from firebeton(ceramic) LACFIRE 1800/20 SiC with high temperature and mechanical resistance. The heating chamber is very easy to clean by removing of the some parts of the blocks. Modern technical solution of the boiler body and heating space insure perfect firing with high efficiency and low creation of ill substance in the emmisions. On the bottom of the feeding space are massive cast iron grates, where the ash falls down to the ashtray. The ashtray is in a separate part of the boiler. This construction allows to achieve very high temperature in the heating chamber  and long time to hold emmisions in the boiler for its completly firing.



In the boiler is integrated a cupper security exchanger against overheating. 

The boiler is equipped with exhaust flue gas fan EBM-PAPST, which ensures easy operation and minimalizes smudging by fuel feeding. Boiler is controlled with a modern mikroproccesor regulator.



Boiler is also equipped with front integrated door, which get the boiler a well-knit design and also reduce the temperature of the front touch surface.




Advantages of boilers MODRATHERM PYROSTAR DUO :


  • firing of soft and hard wood, wood briquetts and pellets
  • the primary and secondary air is preheated on a high temperature
  • high efficiency – low wood consumption
  • enviromental firing – low emmisions – emissions class 5 according EN 303-5 
  • integrated security exchanger against overheating
  • automatical shutt down of exhaust fan by the wood burn out
  • big feeding volume
  • solo aship part separate from burning space – cleaing also during firing
  • termostatic regulation of exhaust fan
  • segmented ceramic firing chamber LAC FIRE 1800/20 SiC with high temperature and mechanical resistance
  • integrated exhaust fan – minimizing of smudging by feeding
  • boiler controlled with modern mikroproccesor regulator – high comfort of controlling the central heating
  • integrated Lambda probe Bosch LSU 4.9 and servomotor Belimo CM24
  • automatic burners ignition
  • automatic burners cleaning



The operation of the boiler is controlled by a modern microprocessor controller AK 5000 with Lambda regulation with the lambda probe Bosch LSU 4.9 and servomotor Belimo CM24. The lambda probe Bosch is installed on the chimney of the boiler. The servomotor Belimo is installed on the left side of the boiler. The lambda probe mesures the O2 ratio in the flues and according to the volume of O2 controlls the Belimo servomotor. The boiler can be connected to the heating system of threaded connections G 6 / 4. Connectiing socket of the security exchanger is made with threads G 1 / 2 ".