Pressureless hot water boiler
KDNH series in the small capacity type, KDNH series in the large capacity type
KDNH series in the small capacity type
KDNH series in the large capacity type
Operating principle and features
  • The boiler body structure is designed with a 3-pass inverted combustion method that adopts a special spiral flue and operates at 95℃ or less in a pressure-free condition where the expansion tank is directly attached. It is a boiler where no license and/or inspection are required as the boiler body pressure never exceeds atmospheric pressure and is absolutely safe from explosion. 4-level safety devices of temperature control switch, water level controller, overheat prevention switch and overflow line further ensures the safety of the boiler.
Features
  • Indirectly heated stainless heat exchanger provides hygienic hot water without any scale and rust accumulation.
  • Up to 3 circuits of heat exchangers for heating, hot water supply and heating can be installed in one boiler body.
  • As the heat exchanger, hot water heater, water pump, and condensate tank required for steam boiler installation can be omitted, installation space, initial investment, electricity and labor costs can be greatly saved.
  • As the boiler water is dissolved oxygen free soft water and is heated at a low temperature of 95℃ or less, the heat exchanger do not experience scale adherence and exhibit high efficiency
  • It is a high-performance, high-efficiency boiler that combines the latest European technology and Dongkwang's know-how with the technology provided by Naval, Italy.
  • The artificial intelligence D-Brain control enables easier operation and management. (Option)
  • Attaching a low-NOx burner ensures fuel cost saving, and NOx of 40 ppm or less is guaranteed for operation under 4% of O₂. (Option)
  • You can drastically reduce fuel costs by attaching a condensing economizer to the flue. (Option)
Standard specifications for pressure-free pipe water type of hot water boiler KDNH series
Category Unit KDNH-10 KDNH-15 KDNH-20 KDNH-25 KDNH-30 KDNH-35 KDNH-40 KDNH-45 KDNH-50 KDNH-60 KDNH-80 KDNH-100 KDNH-120 KDNH-130 KDNH-150 KDNH-160 KDNH-200 KDNH-250 KDNH-300
Boiler specifications Rated heat output MW 0.12 0.17 0.23 0.29 0.35 0.41 0.47 0.52 0.58 0.70 0.93 1.16 1.40 1.51 1.74 1.86 2.33 2.91 3.49
kcal/h 100,000 150,000 200,000 250,000 300,000 350,000 400,000 450,000 500,000 600,000 800,000 1,000,000 1,200,000 1,300,000 1,500,000 1,600,000 2,000,000 2,500,000 3,000,000
Efficiency % 91% or more
Heating area 5.43 5.85 8.28 8.28 10.09 10.09 12 12 13 15.1 16.9 18 21.7 21.7 25.3 25.3 29.6 38 42
Control method - ON - OFF HI - LOW - OFF
Total power consumption kW (0.29) (0.34) 0.51(0.51) 0.51(0.69) 0.88(0.69) 0.88(0.88) 1.5(1.5) 2.7(3.5) 4.5(3.5) 4.5(8.0) 6.0(8.0) 6.0(11.5)
Blower power consumption kW (0.15) (0.20) 0.37(0.51) 0.37(0.55) 0.74(0.55) 0.74(0.74) 1.1(1.1) 2.2(3.0) 4.0(3.0) 4.0(7.5) 5.5(7.5) 5.5(11.0)
Circulation pump power consumption kW 0.04 0.4
Power V 220V x 1ø x 60Hz 380V x 3ø x 60Hz
Fuel consumption LNG N㎥/h - - 22.0 27.5 33.0 38.5 44.0 49.5 54.9 65.9 87.9 109.9 131.9 142.9 164.8 175.8 219.8 274.7 329.7
Propane(LPG) .- - 9.8 12.3 14.7 17.2 19.6 22.1 24.5 27.6 36.9 46.1 57.0 61.8 71.3 76.1 95.1 118.8 142.6
Butane - - 7.5 9.3 11.2 13.0 14.9 16.8 18.6 21.0 28.0 34.9 41.9 45.4 52.4 55.9 69.9 87.4 104.8
Diesel kg/h 10.6 16 21.3 26.7 32.0 37.3 42.7 48.0 53.3 64.0 85.4 106.7 128.0 138.7 160.0 170.7 213.4 266.7 320.1
Connection diameter Oil inlet A 15 15 15 15 15 15 15 15 15 15 25 25 25 25 25 25 25 25 25
Gas inlet - - 25 40 40 40 40 40 40 40 40 40 40 40 50 50 50 65 65
Flue ø 200 200 200 200 250 250 250 250 300 300 350 350 400 400 400 400 450 550 600
Base size Width(W) mm 1,060 1,060 1,200 1,200 1,300 1,300 1,450 1,450 1,410 1,410 1,570 1,570 1,610 1,610 1,610 1,610 1,650 1,700 1,900
Length(L) 1,060 1,060 1,200 1,200 1,300 1,300 1,450 1,450 2,530 2,670 2,810 2,970 3,110 3,110 3,270 3,270 3,560 3,560 4,200
Height(H) 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
External size Width(W) mm 1,060 1,060 1,000 1,000 1,100 1,100 1,250 1,250 1,510 1,510 1,670 1,670 1,710 1,710 1,710 1,710 1,750 2,000 2,200
Length(L) 1,450 1,450 1,740 1,740 1,870 1,870 2,110 2,110 3,530 3,670 4,140 4,300 4,490 4,490 4,650 4,650 4,980 4,980 5,200
Height(H) 2,340 2,340 2,500 2,500 2,550 2,550 2,560 2,560 2,130 2,130 2,340 2,340 2,440 2,440 2,440 2,440 2,540 2,750 3,250
Product weight kg 550 570 750 770 920 950 1,150 1,200 13,500 2,000 2,850 3,420 3,600 3,900 4,350 4,600 5,300 5,750 6,950
  • The external size may vary depending on the control panel and burner specifications.
  • Specifications in ( ) are diesel boiler specifications.
For heating and hot water circulation {60℃ → 70℃}
Category Unit KDNH
-10
KDNH
-15
KDNH
-20
KDNH
-25
KDNH
-30
KDNH
-35
KDNH
-40
KDNH
-45
KDNH
-50
KDNH
-60
KDNH
-80
KDNH
-100
KDNH
-120
KDNH
-130
KDNH
-150
KDNH
-160
KDNH
-200
KDNH
-250
KDNH
-300
For heating and hot water circulation Rated heat output MW 0.12 0.17 0.23 0.29 0.35 0.41 0.47 0.52 0.58 0.7 0.93 1.16 1.40 1.51 1.74 1.86 2.33 2.01 3.49
kcal/h 100,000 150,000 200,000 250,000 300,000 350,000 400,000 450,000 500,000 600,000 800,000 1,000,000 1,200,000 1,300,000 1,500,000 1,600,000 2,000,000 2,500,000 3,000,000
Circulation volume 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000 60,000 80,000 100,000 120,000 130,000 150,000 160,000 200,000 250,000 300,000
Maximum operating pressure MPa{kgf/㎠} 1{10}
Pressure loss MPa{mH2O} 0.012{0.12} 0.017{0.17} 0.02{0.2} 0.018{0.18} 0.022{0.22} 0.03{0.3} 0.033{0.33} 0.022{0.22} 0.03{0.3} 0.03{0.3} 0.033{0.33} 0.035{0.35} 0.04{0.4}
Material - Stainless steel pipe
Connection diameter A 40 40 50 50 50 50 65 65 65 80 80 100 100 100 100 100 150 150 150
For hot water supply (298K → 338K) {25℃ → 65℃}
Category Unit KDNV
-10
KDNV
-15
KDNV
-20
KDNV
-25
KDNV
-30
KDNV
-35
KDNV
-40
KDNV
-45
KDNV
-50
KDNV
-60
KDNV
-80
KDNV
-100
KDNV
-120
KDNV
-130
KDNV
-150
KDNV
-160
KDNV
-200
KDNV
-250
KDNV
-300
For heating and hot water supply Rated heat output MW 0.12 0.17 0.23 0.28 0.35 0.41 0.47 0.52 0.58 0.7 0.93 1.16 1.40 1.51 1.74 1.86 2.33 2.01 3.49
kcal/h 100,000 150,000 200,000 250,000 300,000 350,000 400,000 450,000 500,000 600,000 800,000 1,000,000 1,200,000 1,300,000 1,500,000 1,600,000 2,000,000 2,500,000 3,000,000
Circulation volume 2,500 3,750 5,000 7,500 8,750 10,000 11,250 12,500 15,000 20,000 25,000 30,000 32,500 37,500 40,000 40,000 62,500 75,000
Maximum operating pressure MPa{kgf/㎠} 1{10}
Pressure loss MPa{mH2O} 0.06{0.06} 0.015{0.15} 0.018{0.18} 0.015{0.15} 0.02{0.2} 0.024{0.24} 0.033{0.33} 0.022{0.22} 0.03{0.3} 0.022{0.22} 0.035{0.35} 0.04{0.4}
Material - Stainless steel pipe
Connection diameter A 40 40 40 40 40 40 50 50 50 50 65 65 65 65 80 80 80 100 100
For hot water supply (278K → 338K) {5℃ → 65℃}
Category Unit KDNH
-10
KDNH
-15
KDNH
-20
KDNH
-25
KDNH
-30
KDNH
-35
KDNH
-40
KDNH
-45
KDNH
-50
KDNH
-60
KDNH
-80
KDNH
-100
KDNH
-120
KDNH
-130
KDNH
-150
KDNH
-160
KDNH
-200
KDNH
-250
KDNH
-300
For heating and hot water circulation Rated heat output MW 0.12 0.17 0.23 0.29 0.35 0.41 0.47 0.52 0.58 0.7 0.93 1.16 1.40 1.51 1.74 1.86 2.33 2.01 3.49
kcal/h 100,000 150,000 200,000 250,000 300,000 350,000 400,000 450,000 500,000 600,000 800,000 1,000,000 1,200,000 1,300,000 1,500,000 1,600,000 2,000,000 2,500,000 3,000,000
Circulation volume 1,667 2,500 3,333 4,167 5,000 5,833 6,667 7,500 8,333 10,000 13,333 16,667 20,000 21,667 25,000 26,667 33,333 41,667 50,000
Maximum operating pressure MPa{kgf/㎠} 1{10}
Pressure loss MPa{mH2O} 0.006{0.06} 0.015{0.15} 0.018{0.18} 0.015{0.15} 0.02{0.2} 0.024{0.24} 0.033{0.33} 0.022{0.22} 0.03{0.3} 0.035{0.35} 0.04{0.4}
Material - Stainless steel pipe
Connection diameter A 40 40 40 40 40 40 50 50 50 50 65 65 65 65 80 80 80 100 100
  • The above specification table is indicated as follows.
    - The fuel calorific value of fuel consumption is based on the low-level calorific value.
    - LNG : 10,000 kcal/N㎥
    - LPG(Propane) : 22,400 kcal/N㎥
    - LPG(Butane) : 29,500 kcal/N㎥





  • Design flow temperature condition for heating and hot water circulation 333~343K {60~70℃}
  • Design flow temperature condition for hot water supply 298~338K {25~65℃}, 278~338K {5~65℃}
  • The rated heat output for heating and hot water supply is given for each individual use, and in the case of simultaneous use, the total is the boiler heat output.
  • The following tolerances are included due to the measurement errors of the measuring instrument or measuring personnel.
    - Boiler efficiency measurement error ±1%
  • The above boiler efficiency is based on the true heat generation (low heat generation).
  • The above specification table is subject to change without notice.
  • This specification is based on a gas boiler. For detailed specifications, refer to the specification table.
+82-1670-8919
Dong Kwang Boiler Co., LTD.
CEO : ParkJeongYeon
Add : A-701, Chungang Circulation Complex, 15, Gyeongin-ro 53-gil, Guro-gu, Seoul, Korea
Fax : +82-2-6258-8990
E-mail : dk498125 @ daum.net
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ALL RIGHTS RESERVED
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