From Longman Dictionary of Contemporary Englishimmersion heaterimˈmersion ˌheater noun [countable] British English DHan electric water heater that provides hot water for a house
Examples from the Corpus
immersion heater• Immersion heater spanner Electric immersion heaters fit into a large screwed boss on the top or side of a hot water cylinder.• Built-in airing cupboard incorporating lagged hot water tank and immersion heater.• You can hire the correct immersion heater spanner, but their cheapness probably makes buying one a better answer.• Separate airing cupboard with foam dipped hot water cylinder, immersion heater and timer for boiler.• Simply switch to the Economy 7 tariff and update your immersion heater with an inexpensive Maxistore conversion package. 