What does economiser mean?
An economiser is a noun denoting either a device that conserves resources or, less commonly, a person who spends carefully. The dominant modern usage is technical: in engineering, an economiser is a heat-recovery apparatus — most familiar as the section of a boiler that uses hot exhaust gases to pre-heat incoming feedwater, thereby improving efficiency and cutting fuel consumption. Similar devices appear in refrigeration systems, power stations, and building ventilation, where an 'economiser cycle' draws in cool outside air instead of running mechanical cooling. The word carries connotations of thrift and efficiency, whether applied to machinery or to people, and derives from the Greek-rooted family around 'economy', entering English through Latinised forms in the eighteenth and nineteenth centuries alongside industrialisation. It is spelled 'economizer' in American English.
A device that reduces consumption of fuel or energy, especially a boiler component that recovers waste heat from flue gases to pre-heat feedwater.
"The retrofit included a new economiser fitted between the boiler and the chimney."
Almost always used in engineering contexts; often modified by words like 'boiler', 'flue gas', or 'waste-heat'.
A person who economises; someone careful and sparing in their use of money or resources.
"An inveterate economiser, he reused tea leaves until they gave up all flavour."
Less common today than the device sense; can sound slightly old-fashioned.
Regular plural; used when referring to multiple devices or multiple thrifty individuals.
"Both boilers were fitted with economisers during the upgrade."
In a power station, the economiser earns its name twice over — it recycles heat that would otherwise vanish up the chimney, squeezing extra efficiency out of fuel you've already paid for.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of economiser
Economiser derives ultimately from the Greek oikonomos ('household manager'), via Latin oeconomus and French économie, which gave English 'economy' in the sixteenth century. The verb 'economise' formed on this base, and 'economiser' arose by adding the agent/instrument suffix '-er'. The spelling with '-ise' reflects British practice; American English regularises it as 'economizer'. Cognates include 'economist' and 'economic'.
How economiser is actually used
Predominantly British spelling; American English uses 'economizer'. In modern technical writing, sense 1 (the device) is far more common than sense 2 (a thrifty person). The device sense appears chiefly in engineering contexts such as boilers, HVAC systems, and power generation.
Easily confused with economiser
Economiser is simply the British spelling of the same word; economizer is the American spelling.