Inzonex Takeda Vienna · Calculation Annex ← Back to proposal

Per-element calculations

Detailed thermal balance per element group: surface area breakdown, convection coefficient, radiation flux, and before/after losses. All inputs match the executive proposal — published here for verification by Takeda's energy/engineering team.

Method & constants

h_conv = 1.42 × (ΔT / L)^0.25 [W/(m²·K)]
Q_conv = h_conv × A × ΔT [W]
q_rad = ε × σ × (T_s⁴ − T_a⁴) [W/m²]
Q_rad = q_rad × A [W]
R_ins = 0.050 / 0.038 = 1.316 [(m²·K)/W]

Contents

  1. Front doors — steam boilers
  2. Water column valves
  3. Feed water lines
  4. Rear inspection hatches
  5. Support brackets
  6. HW header pumps (shared)
  7. Safety valves
  8. Bottom inspection hatches
  9. Loos HW boiler — front door
  10. HW lines — steam boiler side
  11. Centre valve + sensor DN50
  12. Condensate return line
  13. Green Wilo pumps

1.Front doors — steam boilers

Quantity: 2 (one per boiler)T_s: 119 °C (392 K)ΔT: 99 KHours: 8,760 h/yr

Surface area — per door

SurfaceArea (m²)
Front face 0.90 × 1.100.990
Top + bottom 2 × (0.90 × 0.15)0.270
Left + right 2 × (1.10 × 0.15)0.330
Bolt flange perimeter (4 m × 0.08)0.320
Hinges (2 pcs)0.030
Ribs / guides0.050
Burner ring (Ø 0.50 × 0.05)0.080
Misc (hatch, hardware)0.020
Total per door2.100

Heat balance — per door

TermValue
h_conv = 1.42 × (99/1.10)^0.254.37 W/(m²·K)
Q_conv = 4.37 × 2.10 × 99908 W
q_rad (ε 0.85, T 392 K)784 W/m²
Q_rad = 784 × 2.101,646 W
Q_before / door2,554 W
T_surface_new (iter)≈ 29 °C
q_through = 68.4 W/m²—
Q_after / door144 W
Before · 2 doors
5,108W
After · 2 doors
288W
Saved
4,820W
Reduction 94.4 %. Both boilers operate rotating duty/standby — losses are continuous.

2.Water column valves

Quantity: per boiler × 2T_s: 181 °C (454 K)ΔT: 161 KHours: 8,760 h/yr

Elements per boiler

ElementQtyArea (m²)
Spirax gate valve DN1510.044
Spirax pneumatic regulator DN1510.055
Pipe 50 mm DN1510.003
Flanges with sensors DN65 (h 15 cm)20.286
Flanges to pressure gauges DN25 (h 10 cm)40.124
Ball valves DN2520.096
Pipes 80 mm DN2520.017
Total per boiler0.625

Heat balance — per boiler

TermValue
h_conv (L = 0.15 m)8.12 W/(m²·K)
Q_conv818 W
q_rad (ε 0.85, T 454 K)1,692 W/m²
Q_rad1,058 W
Q_before / boiler1,876 W
Q_after / boiler73 W
Before · 2 boilers
3,752W
After · 2 boilers
146W
Saved
3,606W
Reduction 96.1 %. Densely packed valve clusters — covered with custom-fit modular jackets, snap closures.

3.Feed water lines

Quantity: 2 mirrored lines + centre / boiler × 2T_s: 105 °C (378 K)DN40 throughoutHours: 8,760 h/yr

One side of mirrored line

ElementLengthArea (m²)
Pipe stub DN4010 cm0.015
Gate / ball valve DN40 + 2 flanges30 cm0.125
Strainer DN40 + 2 flanges30 cm0.130
Pipe elbow + straight DN4030 cm0.046
Grundfos CR pump (Ø 150 × 550 mm + 2 flanges)55 cm0.336
Pipe with elbow DN401 m0.152
Pipe DN4030 cm0.046
Valve + check valve DN4030 cm0.130
One side0.980

Centre elements

ElementArea (m²)
Flange DN40 + pipe stub 15 cm0.044
Valve with check valve DN400.130
Pneumatic control valve DN400.135
Centre total0.309

Heat balance — per boiler

TermValue
Total area per boiler (2 × 0.980 + 0.309)2.269 m²
h_conv6.92 W/(m²·K)
Q_conv1,334 W
q_rad628 W/m²
Q_rad1,425 W
Q_before / boiler2,759 W
Q_after / boiler135 W
Before · 2 boilers
5,518W
After · 2 boilers
270W
Saved
5,248W
Reduction 95.1 %. CR pump motors excluded from insulation.

4.Rear inspection hatches

Quantity: 2T_s: 210 °C (483 K) — hottest element1.00 × 0.80 × 0.22 mHours: 8,760 h/yr

Surface area — per hatch

SurfaceArea (m²)
Front face 1.00 × 0.800.800
Top + bottom 2 × (1.00 × 0.22)0.440
Left + right 2 × (0.80 × 0.22)0.352
2× stub nozzles DN50 (10 cm)0.043
Ball valve DN400.065
Bolt flange perimeter (3.6 m × 0.05)0.180
Bolts (16 × M16 × 30 mm)0.024
Total per hatch1.904

Heat balance — per hatch

TermValue
h_conv (L = 0.80 m)5.58 W/(m²·K)
Q_conv2,019 W
q_rad (ε 0.85, T 483 K)2,267 W/m²
Q_rad4,316 W
Q_before / hatch6,335 W
Q_after / hatch253 W
Before · 2 hatches
12,670W
After · 2 hatches
506W
Saved
12,164W
Single biggest loss source — 28 % of total. Reduction 96.0 %.

5.Support brackets

Quantity: 2 / boiler · 4 totalT_s: 85 °CInsulated zone 30 × 50 cm (upper hot part)Hours: 8,760 h/yr

Area

ItemArea (m²)
Per bracket (front + back + ribs + edges)0.810
Per boiler (2 brackets)1.620
4 brackets total (2 boilers)3.240
Brackets are massive structural elements — both faces, ribs, edges and gusset plates radiate independently and are counted toward the area.

Heat balance — 4 brackets

Before
2,424W
After
148W
Saved
2,276W
Reduction 93.9 %. Lower legs left bare (cold zone).

6.HW header pumps (shared)

T_s: 72 °C (345 K)Shared between boilers — counted ×1Motors excludedHours: 8,760 h/yr

Pumps

PumpQtyArea (m²)
Large Wilo centrifugal (PU0845)10.494
Small Wilo inline20.414
Medium green Wilo centrifugal20.688
Total1.596

Heat balance

TermValue
h_conv5.71 W/(m²·K)
q_rad328 W/m²
Q_before997 W
Q_after58 W
Saved
939W
Reduction 94.2 %. Two-piece volute jackets, motor cut-outs.

7.Safety valves

Quantity: 2 / boiler · 4 totalT_s: 181 °CDN50 inlet / DN32 outlet, spring-loadedHours: 8,760 h/yr

Area

ItemArea (m²)
Per valve0.104
Per boiler (2 valves)0.208
4 valves total0.416
Upper discharge stack NOT insulated (must remain accessible & visible).

Heat balance — 4 valves

Before
1,248W
After
48W
Saved
1,200W
Reduction 96.2 %. Highest reduction in the project.

8.Bottom inspection hatches

Quantity: 2T_s: 180 °C (453 K)Area: 0.320 m² eachHours: 8,760 h/yr

Heat balance — per hatch

TermValue
Area0.320 m²
Q_before / hatch844 W
Q_after / hatch37 W

2 hatches total

Before
1,688W
After
74W
Saved
1,614W
Reduction 95.6 %.

9.Loos HW boiler — front door

Quantity: 1T_s: 115 °C (estimated)1.45 × 1.45 × 0.22 mHours: 4,380 h/yr (6 months)

Surface area

SurfaceArea (m²)
Front face 1.45 × 1.452.103
Side walls 4 × (1.45 × 0.22)1.276
Bolt flange (5.8 m × 0.06)0.348
Bolts (20 × M16 × 30 mm)0.030
Burner ring + misc0.090
Total3.847

Heat balance

Before
4,322W
After
254W
Saved
4,068W
Reduction 94.1 %. Annual hours 4,380 (heating season only) — temperature to confirm on next site visit.

10.HW lines — steam boiler side

Quantity: 1 line / boiler, mirrored × 2 sides × 2 boilersT_s: 105 °CDN40 throughoutHours: 8,760 h/yr

One side of mirrored line

ElementArea (m²)
Globe valve DN40 (30 cm)0.125
Pipe DN40 (100 cm)0.152
Grundfos CR pump DN40 (h 55 cm + flanges)0.336
Pipe stub DN40 (~15 cm)0.023
Strainer DN40 (30 cm)0.130
Ball valve DN40 (~20 cm)0.096
Pipe elbow DN40 (30 cm)0.046
One side0.908
Per boiler (× 2 mirrored): 1.816 m²

Heat balance — 2 boilers

Before
4,416W
After
216W
Saved
4,200W
Reduction 95.1 %.

11.Centre valve + sensor DN50

Quantity: 1 assembly / boiler · 2 totalT_s: 181 °CArea: 0.275 m² per assemblyHours: 8,760 h/yr

Per assembly

Globe valve DN50 + sensor cluster DN50 — 0.275 m² combined surface.

Heat balance — 2 assemblies

Before
1,650W
After
64W
Saved
1,586W
Reduction 96.1 %.

12.Condensate return line

Quantity: 1 sharedT_s: 95 °C (estimated)DN50Hours: 8,760 h/yr

Elements

ElementArea (m²)
Float steam trap (~ 35 × Ø 25 cm + sphere)0.416
Sight glass (15 cm)0.113
Y-strainer (25 cm)0.164
Globe valve (25 cm)0.164
Connecting pipes (~30 cm)0.057
Total0.914

Heat balance

Before
889W
After
48W
Saved
841W
Reduction 94.6 %. Sight glass left exposed for visual inspection.

13.Green Wilo pumps (additional)

Quantity: 5T_s: 72 °CPer pump area: 0.344 m²Hours: 8,760 h/yr

Area

ItemValue
Per pump0.344 m²
5 pumps total1.720 m²
Same geometry as medium-green Wilo in Section 6. Motors excluded.

Heat balance — 5 pumps

Before
1,076W
After
63W
Saved
1,013W
Reduction 94.1 %.

Grand total — all 13 element groups

Total area30.351 m²
Heat loss BEFORE45,758 W (45.76 kW)
Heat loss AFTER2,183 W (2.18 kW)
Reduction95.2 %
Annual energy saved363,899 kWh / yr
Gas saved (÷ 0.90 efficiency)404,332 kWh / yr
Cost saving @ €60/MWh€24,260 / yr
CO₂ avoided (0.202 kg/kWh)81.7 t / yr
Investment (turnkey)€19,050
Payback9.4 months
3-year net value€53,730
3-year ROI282 %