A main stop valve is the mounting on the steam take-off that isolates the boiler from the plant. The steam take-off and stop valves sit at the boiler’s saturation temperature — the FLIR survey measured 190 °C, the hottest surface on the boiler, bare.
Figures are for one boiler. Surface temperatures from a real FLIR survey of a UK commercial boiler house; CAD surface areas uplifted ×1.4 for bolts and irregular geometry; ISO 12241 steady-state (50 mm core, ambient 28 °C, air movement 0.5 m/s).
Drag-free toggle. Visible in this view: steam take-off and stop valves — 190 °C, bare cast bodies.3D model: Inzonex · equipment rights belong to the manufacturer
Valves are the surface insulation contractors skip most, because their cast shapes don’t suit rigid boxes — yet they run at the hottest temperature on the boiler, the saturated-steam 190 °C.
Per unit area a bare valve loses more than a flat plate at the same temperature. Two-part removable covers insulate the body and seats while leaving the stem and gland serviceable.
| Element (this view) | Temp °C | Area m² | Bare W | Insulated W | Surface °C | Cut |
|---|---|---|---|---|---|---|
| Steam valves | 190 | 0.45 | 1,430 | 70 | 36 | −95% |
| Steam valves & piping, per boiler | 0.45 | 1,430 | 70 | ≤45 | −95% |
ISO 12241, 50 mm Inzonex modular core, ε(bare)=0.9, ε(jacket)=0.85, hconv at 0.5 m/s. Insulated figures are conservative steady-state.
The steam take-off and stop valves sit at the boiler’s saturation temperature, 190 °C — the hottest measured surface. Two-part removable covers insulate the bodies and cut ~95% of the loss, with the stems left exposed for service.
Every module here re-opens for access.
Every surface on this view is covered by an Inzonex modular removable panel: a PAROC stone-wool core (50 mm) in a silicone outer shell — or a more durable PTFE shell as an option. The form-fitting build unbuttons for access and refits after each maintenance cycle. The outer surface drops to a touch-safe ≤45 °C.
Industries that run this boiler
Put in your boiler count, fuel price and running hours — get energy, £ and payback for the whole room.
Open calculator → CarbonEvery bare kilowatt is real fuel and real carbon. See the tonnes and the EU-ETS cost behind it.
Carbon hub → 3D modelRotate the Bosch UL-S model, toggle bare vs insulated, and jump to every other surveyed surface.
Open 3D model →The FLIR survey measured the steam valves at 190 °C bare — the hottest surface on the boiler.
Yes — with two-part removable covers shaped to the body. They cut ~95% of the loss yet pull off for inspection, with the stems left exposed.
On the surveyed Bosch the steam valves lost 1.43 kW bare, cut to 0.07 kW insulated — a 95% reduction.
Selected readings from this boiler survey. This surface is the marked point.
Saturated steam has one temperature for each pressure. That is why a valve body runs hot: it is held near the temperature of the steam passing through it, and that temperature is set by the pressure in the line, not by the burner.
| Gauge pressure, bar | Absolute, bar | Saturation temperature |
|---|---|---|
| 0 | 1.013 | 100.0 |
| 1 | 2.013 | 120.2 |
| 2 | 3.013 | 133.5 |
| 3 | 4.013 | 143.6 |
| 4 | 5.013 | 151.8 |
| 5 | 6.013 | 158.8 |
| 6 | 7.013 | 164.9 |
| 7 | 8.013 | 170.4 |
| 8 | 9.013 | 175.4 |
| 9 | 10.013 | 179.9 |
| 10 | 11.013 | 184.1 |
| 12 | 13.013 | 191.6 |
| 14 | 15.013 | 198.3 |
The steam valve set on this page reads 190 °C on the outside. Saturated steam is at 191.6 °C when the line is at 12 bar gauge, so a body at this surface temperature is running close to line temperature — the metal has almost nothing between it and the steam.
Saturation temperatures are standard physical data for water and steam, not our measurement. What we measured is the surface: a thermal camera reads the outside of the body, which sits at or below the temperature of the steam inside it. Absolute pressure is gauge plus 1.013 bar.
Every figure on this page comes from the same chain: a radiometric camera reading of the surface, an area rebuilt in CAD from the surveyed machine, and an ISO 12241 calculation from those two. The instrument settings, the area allowance, the energy basis and the list of what was not measured are set out once, in full, on the method page.
| Survey | Bosch UL-S, steam valves and piping. FLIR S62 Pro, emissivity 0.90, reflected 25 °C, 3 m, full radiometric correction. Peak on this view 190 °C. |
| Geometry | Rebuilt in CAD from the surveyed machine. This view carries 1 element group(s) and sheds 1.4 kW bare. The ×1.4 factor is a geometry allowance for bolts, seams and irregular surface — it is not a measured area. |
| Calculation | ISO 12241 steady state. Heat loss is calculated from the measured surface temperature and the modelled area — it is not metered. Full method, basis and limits. |
| Largest single item | Steam valves, 1.4 kW on this view. |
| Regulation | The Pressure Systems Safety Regulations 2000 · HSE L122, Safety of pressure systems · HSE INDG261, Pressure systems |