BOILERS / METHOD / COMPARISONS
Economiser insulation: operating hours and fuel-price scenarios
Based on the published Boilers surveys and model outputs. Read the source scope alongside each comparison.
Published inputs and what they mean
Reference component: the surveyed Cochran economiser, 18,327 W bare and 954 W panelled in the published calculation. The difference is 17.373 kW. The table holds this thermal load fixed and changes annual operating hours and fuel price only.
| Hours/year | Useful heat retained MWh/year | €40/MWh fuel | €60/MWh fuel | €100/MWh fuel |
|---|---|---|---|---|
| 2,000 | 34.75 | €1,544 | €2,316 | €3,861 |
| 4,000 | 69.49 | €3,089 | €4,633 | €7,721 |
| 5,840 | 101.46 | €4,509 | €6,764 | €11,273 |
| 7,700 | 133.77 | €5,945 | €8,918 | €14,864 |
How to read the combinations
Useful heat = 17.373 kW × hours ÷ 1,000. Fuel energy = useful heat ÷ 0.90. Fuel cost saving = fuel energy × fuel price. The 90% efficiency is a planning assumption, not a measured boiler efficiency. Fuel prices are scenarios, not tariffs or quotations.
At 7,700 hours and €60/MWh the scenario gives €8,918/year, rounded. Two identical components at the same load and schedule would double this estimate; a second boiler with different surfaces would require its own input data. Hours exclude shutdowns and periods when the stated temperature is not maintained.
What the table cannot tell you
It does not predict savings from a different insulation thickness or temperature. Those changes need a new thermal calculation. Payback requires a project-specific installed cost; no standard price per square metre is assumed here. The panelled loss is a published model output, not a metered fuel saving.