The feed and condensate side runs near 100 °C across the pump, isolation valves, return lines, strainer and blowdown — many small bare surfaces that quietly add up.
FLIR-measured surface tempsCAD areas × 1.4 bolt/irregularityISO 12241 · v = 0.5 m/s
This view. Visible in this angle: feed pump, globe valve, return lines, strainer and blowdown flanges — ~100 °C.3D model: Inzonex · equipment rights belong to the manufacturer
Peak surface
180 °C
Bare, FLIR-measured
Largest loss
1.7 kW
Feed pump
This view, bare
6.2 kW
6 element group(s)
After insulation
≈95%
Surface drops to ≤45 °C
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).
What you are looking at
Boiler feed pump & feedwater heat loss
No single surface here is dramatic, but the feedwater set is a cluster of a dozen-plus warm bodies at ~100 °C — a pump casing, valves, a strainer, return runs and blowdown connections. Each is left bare because it is “small” and needs access.
Added together they are a continuous loss worth insulating, and every one of them needs to stay serviceable. Removable covers and pipe sleeves insulate the set while keeping seals, handwheels, unions and the strainer basket reachable.
Element (this view)
Temp °C
Area m²
Bare W
Insulated W
Surface °C
Cut
Feed pump
100
1.49
1,664
87
33
−95%
Globe valve
100
0.36
402
21
33
−95%
Return lines ×3
100
0.81
905
48
33
−95%
Feed piping ×8
100
1.20
1,340
70
33
−95%
Filter / strainer
100
0.36
402
21
33
−95%
Blowdown flanges ×2
180
0.52
1,501
76
39
−95%
Feedwater & blowdown side view, per boiler
4.7
6,214
323
≤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, not best-case.
Element by element
Why each one is left bare — and how it gets insulated
Feed pump · 100 °C · 1.7 kW bare
The boiler feed pump body and its casing run near 100 °C. A removable cover insulates the volute while leaving the seal, bearings and coupling accessible for service.
Globe valve · 100 °C · 0.4 kW bare
Feed-line isolation valve at ~100 °C — another small cast body left bare. A shaped cover insulates it without seizing the handwheel.
Return lines · 100 °C · 0.9 kW bare
Condensate and return runs at ~100 °C. Individually minor, but several short bare sections in the feed set add up to real continuous loss.
Feed piping · 100 °C · 1.3 kW bare
Multiple short bare pipe sections around the feed set. Removable pipe sleeves insulate them and still allow union and flange access.
Filter / strainer · 100 °C · 0.4 kW bare
The feed strainer body sits at ~100 °C and must open for cleaning — a textbook case for a removable, re-openable cover rather than fixed lagging.
Blowdown flanges · 180 °C · 1.5 kW bare
Blowdown connections see boiler-pressure temperature in bursts and are left bare for safety access. A removable shroud insulates the standing loss while keeping the valve operable.
Geometry that re-opens for access is the core idea behind the Inzonex modular design (UK patent application GB2508992.1).
The pump casing/volute can be insulated with a removable cover at ~100 °C, while the seal, bearings and coupling stay accessible. It removes a standing loss and a hot-touch hazard.
How hot is the feedwater side of a boiler?
On the surveyed Cochran the feed pump, valves, returns, strainer and blowdown ran near 100 °C.
Are small bare pipes worth insulating?
Individually no, collectively yes — a feed set of a dozen warm bodies is a continuous multi-hundred-watt loss, cut ~95% with removable sleeves and covers.
More of this boiler
Other surveyed views
Every face of the Cochran model has its own measured surfaces. Explore them from the 3D hub.
