immersion heater 
noun
An electric heating element that is positioned in the liquid to be heated, typically in a domestic hot-water tank.It is believed the cause of the fire was an electrical fault in the wiring of an electric immersion heater....
- Heating is by means of an oil-fired central heating system which is augmented by a separate immersion heater for the hot water supply.
- She has hot water because that is heated through an immersion heater.
- withering
- witheringly
- witherite
- wither on the vine
- withers
- withershins
- with flying colours
- with forked tongue
- with friends like ——, who needs enemies?
- with God
- with good (or bad) grace
- withhold
- withholder
- withholding tax
- within
- within a bull's roar (of)
- within an ace of
- within an inch of
- within a whisker of
- within call
- within cooee
- within hail
- within limits
- within (or beyond) arm's reach
- within (or in) reach