Boilers in closed system

Defro Duo Uni NZ

DEFRO DUO UNI boilers are another two-furnace boilers. Bottom chamber is equipped with innovative trough burner allowing combustion of eco pea coal, qualified fines and crops grains. Upper chamber is created by fixed water-cooled grate, allowing periodical combustion of the other fuels and start-up of boiler in emergency situations. Heat exchanger is completely made of boiler steel of thickness 6-10 mm, while the individual components endangered with action of flames and substances in the flue gases - are made of thickness even 10-12 mm. Boilers are equipped with components increasing operational safety e.g. flap opening sensor, double protection against ignition of fuel in hopper - first implemented by the controller, the second - by automatic, water extinguishing system STRAŻAK (FIRE FIGHTER). Version with innovative controller with touch panel is available as a standard.


Reinforced version NZ with installed cooling coil pipe and compete protective fixtures allowing installation in closed system. NZ version requires extra payment, according to the Boilers Equipment Price List.

wymiennik ciepła wykonany z atestowanej stali kotłowej /gat. P265GH/ o grubości 6-10mm z hut Arcelor Mittal Poland S.A. heat exchanger made of certified boiler steel /grade P265GH/ of 6-10 mm thickness from steel mills of Arcelor Mittal Poland S.A.
sterownik K1 z kolorowym panelem dotykowym obsługującym 4 pompy /c.o., c.w.u., obiegowa, podłogowa/. Możliwość obsługi zaworu mieszającego, sterowanie poprzez GSM lub Internet*, regulowany kąt położenia panelu sterującego controller K1 with colour touch panel servicing 4 pumps /central heating, hot utility water, circulation, floor pump/. Possibility to operate mixing valves, control using GSM or INTERNET*; adjustable angle of control panel
5 lata gwarancji na szczelność wymiennika ciepła, 2 lata na pozostałe elementy i sprawne działanie kotła 5 years of warranty for heat exchanger tightness, 2 years for the remaining components and efficient operation of boiler
 wysoka sprawność cieplna sięgająca 90% dzięki zwiększonemu odzyskowi ciepła ze spalin
high thermal efficiency reaching 90% thanks to increased heat recovery from flue gases
uklad-zamkniety.png boiler adapted for installation in closed system in version DEFRO DUO UNI NZ
dolna komora paleniskowa z wysoko efektownym palnikiem rynnowym bottom furnace chamber with highly effective trough burner
 system automatycznego wodnego gaszenia paliwa z zaworem termostatycznym automatic water fire suppression system with thermostatic valve
dwie komory paleniskowe: dolna z palnikiem automatycznym, górna do spalania drewna /przy załadunku ręcznym/ two furnace chamber: bottom with automatic burner, upper for wood combustion /for manual charging/

(*) - extra payable equipment, installed on Customer’s request

Specification / boiler type Unit 15 20 25 35 50
Power range kW 4,5-15 6,0-20 7,5-25 10,5-35 15,0-50
Heating area m2 1,9 2,4 2,8 3,2 4,4
Area of heated
rooms *
M2 to 200
to 260
to 300 to 370 to 580
Capacity of fuel container *** kg ~178 ~178 ~178 ~228 ~228
Optimum thermal efficiency % ~90,3-90,9
Max. permissible operation
bar 2,5
Required flue gas draught Pa 24 26 28 31 34
Water supply temperature
°C 65/80
Boiler weight *****
kg 459
Boiler water tank capacity l 80 106 114 120 172
Chimney section cmxcm 14x14 14x14 15x15 18x18 20x20
Chimney section Ø mm 160 160 170 200 230
Minimum chimney height m 7 7,5 8
9 10
Width mm 1195 1195 1257 1298 1287
Depth mm 950 1060 1060 1090 1310
Depth** mm 1664 1664 1664 1715 1715
Diameter of supply and return Dn mm G1 ½”
Flue size mm 159
Supply V/Hz
Maximum power consumption W
Maximum power consumption mm
Dimensions of substitute combustion
chamber and charging hole
width 308
  depth 420
  height 203 191 228 253 223
  width x height 308x398


* Maximum area of heated rooms estimated for unit heat demand q=85 W/m2.
** Height of boiler can be additionally adjusted by means of provided levelling legs. Legs regulation varies from 38 to 50 mm.
*** Fuel tank capacity for charging density 0.8 kg/dm3

***** Boiler weight depends on the equipment.

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