Heat Exchanger Insulation: Heat Loss & Savings
Heat exchangers run hot by design, but their bare shells, heads and bonnets leak heat into the plant room. Because the heads are opened for tube cleaning, fixed lagging is rarely refitted — removable jackets keep the unit insulated between services.
Heat loss vs insulated — by surface temperature
| Surface temp | Bare loss | Insulated | Outer surface | Reduction |
|---|---|---|---|---|
| 100 °C | 1,407 W/m² | 76 W/m² | 25 °C | 94.6% |
| 120 °C | 1,839 W/m² | 99 W/m² | 27 °C | 94.6% |
| 150 °C | 2,564 W/m² | 138 W/m² | 29 °C | 94.6% |
| 200 °C | 4,012 W/m² | 210 W/m² | 34 °C | 94.8% |
Per-m² flat-surface flux, ASTM C680 / ISO 12241, 50 mm Lamella (≤220 °C) or 100 mm Wired mat (>220 °C), 20 °C ambient. Multiply by the bare area.
Worked examples (per year, 8,000 h, natural gas)
| Item | Heat saved | Energy/yr | CO₂/yr | € saved/yr |
|---|---|---|---|---|
| A shell-and-tube heat exchanger (4 m², 120 °C) | 7.0 kW | 65 MWh | 13.2 t | €3,799 |
| A plate heat exchanger (2 m², 110 °C) | 3.1 kW | 29 MWh | 5.8 t | €1,671 |
FAQ
How much heat does a bare heat exchanger lose?
At 20 °C ambient (ASTM C680): a shell-and-tube heat exchanger (~4 m², 120 °C) loses about 7.0 kW; a plate heat exchanger (~2 m², 110 °C) about 3.1 kW. Insulating a shell-and-tube heat exchanger saves ≈65 MWh and ≈13.2 t CO₂ per year (8,000 h).
Can you insulate shell-and-tube and similar?
Yes. Exchanger heads and channel covers are opened regularly for cleaning and retubing. Inzonex removable jackets are designed to come off and back on with the maintenance cycle. Inzonex covers shell-and-tube, plate, hairpin and feed-water heaters. The outer surface drops to a touch-safe ≤45 °C and the part stays serviceable.
How much does heat exchanger insulation save?
Each item saves 96–98% of its bare loss. A shell-and-tube heat exchanger at 120 °C saves ≈3,799 €/yr of energy (≈65 MWh, ≈13.2 t CO₂) at typical gas prices; payback is usually under two years.
What insulation thickness is used?
Up to 220 °C surface: 50 mm mineral-wool (Lamella); above 220 °C: 100 mm (Wired mat), because conductivity rises with temperature. Both keep the outer surface ≤45 °C.