Economizer Insulation: Heat Loss & Savings
Boiler economizers recover flue-gas heat into the feed water, but their bare headers, flanges and casing sections still leak heat and are awkward to lag permanently. Removable insulation covers them while keeping the headers and instruments accessible.
Heat loss vs insulated — by surface temperature
| Surface temp | Bare loss | Insulated | Outer surface | Reduction |
|---|---|---|---|---|
| 110 °C | 1,618 W/m² | 88 W/m² | 26 °C | 94.6% |
| 150 °C | 2,564 W/m² | 138 W/m² | 29 °C | 94.6% |
| 180 °C | 3,394 W/m² | 180 W/m² | 32 °C | 94.7% |
| 250 °C | 5,822 W/m² | 154 W/m² | 30 °C | 97.4% |
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 |
|---|---|---|---|---|
| An economizer header / flange (0.5 m², 150 °C) | 1.2 kW | 11 MWh | 2.3 t | €662 |
| An economizer casing section (4 m², 180 °C) | 12.9 kW | 121 MWh | 24.4 t | €7,018 |
FAQ
How much heat does a bare economizer lose?
At 20 °C ambient (ASTM C680): an economizer header / flange (~0.5 m², 150 °C) loses about 1.2 kW; an economizer casing section (~4 m², 180 °C) about 12.9 kW. Insulating an economizer header / flange saves ≈11 MWh and ≈2.3 t CO₂ per year (8,000 h).
Can you insulate economizer headers and similar?
Yes. Economizer headers and flanges are inspected and cleaned. Removable covers come off for access and refit without damage. Inzonex covers economizer headers, flanges, casing sections and feed-water connections. The outer surface drops to a touch-safe ≤45 °C and the part stays serviceable.
How much does economizer insulation save?
Each item saves 96–98% of its bare loss. An economizer header / flange at 150 °C saves ≈662 €/yr of energy (≈11 MWh, ≈2.3 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.