Economiser

An economiser is a heat exchanger that recovers heat from boiler flue gas to preheat the feedwater. It is one of the most common, low-risk boiler efficiency retrofits, cutting the fuel needed to raise feedwater to steam temperature.

By capturing heat that would otherwise leave up the stack, an economiser lowers flue-gas temperature and raises overall boiler efficiency by several points. Condensing economisers go further, recovering latent heat from water vapour in the flue gas where the duty allows. It is a staple of waste-heat recovery on steam plant.

In context and practice

Economiser is a core topic in industrial practice, featured prominently in guides on 'How to improve boiler efficiency', 'Waste heat recovery in industry'. Understanding it is necessary for teams implementing efficiency, maintenance, or decarbonization projects.

Closely related terms include Waste Heat Recovery, Boiler Blowdown, Superheat. These concepts often work together in industrial practice — mastering one usually means understanding all of them.

In your plant: When planning maintenance, reliability or efficiency projects, clarify your approach to economiser. Ask vendors or consultants how they implement it. The specifics matter — two plants with the same definition of economiser may execute it very differently based on their equipment, age, and operational culture. The gap between definition and execution is where real value (or waste) lives.

Measuring success: Economiser programs succeed when you can measure their impact. Set a baseline, implement the practice, and track the outcome — downtime reduction, energy savings, cost avoidance, or compliance improvement. Most plants find that a 3–6 month pilot clarifies the true value and ROI of economiser. Don't guess; measure.

Why it matters: economiser is not an end in itself, but a lever in your plant's overall efficiency and reliability strategy. It works best when part of a system: clear ownership, investment in tools or training, executive sponsorship, and regular review. Isolated initiatives often fizzle. Embedded economiser programs compound, delivering value year after year as the practice matures and spreads.