On a working Cochran package boiler the rear end plate and the economizer behind it run at 126–130 °C — FLIR-measured, bare. Together they are the single largest uninsulated heat loss in the boiler house.
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: end plate (130 °C), economizer (126 °C), behind it — both bare.3D model: Inzonex · equipment rights belong to the manufacturer
The rear (back) plate of a Cochran shell boiler closes the reversal chamber, so the full flue-gas temperature presses against it — 130 °C across a 5.3 m² face. Bolted directly behind it sits the economizer, an 11.3 m² finned block at 126 °C that recovers flue heat but is almost always left completely bare because its shape resists rigid cladding.
These surfaces are the largest avoidable loss in the room. Running 8,000+ hours a year, the back of one boiler radiates tens of kilowatts continuously into the boiler-house air.
| Element (this view) | Temp °C | Area m² | Bare W | Insulated W | Surface °C | Cut |
|---|---|---|---|---|---|---|
| Rear (back) plate | 130 | 5.32 | 9,063 | 471 | 35 | −95% |
| Economizer | 126 | 11.31 | 18,327 | 954 | 34 | −95% |
| Rear / end-plate view view, per boiler | 16.6 | 27,390 | 1,425 | ≤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.
A large, mostly flat face carrying the reversal-chamber heat. Easy to insulate, high payback — but usually left bare because it is “just the back”. A removable panel drops it from 130 °C to ≈35 °C and removes a burn hazard behind the boiler.
Cover: Silicone shell + PAROC stone-wool core (50 mm) · touch-safe design target ≤45 °C (ISO 13732-1 guidance)
18.3 kW of the 27.4 kW on this view, and the surface most often skipped. Finned tube blocks and access doors make rigid lagging impractical, so economizers run uninsulated for their whole life. An Inzonex panel is shaped to the casing and re-opens for tube access, keeping recovered heat in the gas path.
Cover: Silicone shell + PAROC stone-wool core (50 mm) · touch-safe design target ≤45 °C (ISO 13732-1 guidance)
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 Cochran model, toggle bare vs insulated, and jump to every other surveyed surface.
Open 3D model →On the surveyed boiler the rear end plate measured 130 °C bare (FLIR) over a 5.3 m² face; the economizer behind it ran at 126 °C.
About 18 kW continuously — 126 °C over 11.3 m² (CAD ×1.4) by ISO 12241 — the largest single avoidable loss on the boiler.
Yes. A modular removable panel is shaped to the casing and unbuttons for inspection, so it insulates without losing access, unlike rigid cladding.
About 34–39 °C — below the 45 °C touch-safe threshold — with roughly a 95% cut in heat loss.
Selected readings from this boiler survey. This surface is the marked point.
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 | Cochran, rear / end-plate view. FLIR S62 Pro, emissivity 0.90, reflected 25 °C, 3 m, full radiometric correction. Peak on this view 130 °C. |
| Geometry | Rebuilt in CAD from the surveyed machine. This view carries 2 element group(s) and sheds 27.4 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 | Economizer, 18.3 kW on this view. |
From the rear quarter the live-steam fittings come into view — check and main stop valves, the safety valves, the rear manhole, steam flanges and sens…Open the measured page
→/ 02The feed and condensate side runs near 100 °C across the pump, isolation valves, return lines, strainer and blowdown — many small bare surfaces that q…Open the measured page
→/ 03The front door carries the burner and closes onto the furnace tube behind it — a 5.3 m² face at about 120 °C bare. It also has to hinge open for burn…Open the measured page
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