Hot Water Heater Blankets

water heater
a heater and storage tank to supply heated water
Water heating is a thermodynamic process using an energy source to heat water above its initial temperature. Typical domestic uses of hot water are for cooking, cleaning, bathing, and space heating. In industry, both hot water and water heated to steam have many uses.
An appliance for supplying hot water for purposes other than space heating or pool heating.

blankets
Cover completely with a thick layer of something
Stifle or keep quiet (sound)
(blanket) bedding that keeps a person warm in bed; "he pulled the covers over his head and went to sleep"
Take wind from the sails of (another craft) by passing to windward
(blanket) cover as if with a blanket; "snow blanketed the fields"
(blanket) across-the-board: broad in scope or content; "across-the-board pay increases"; "an all-embracing definition"; "blanket sanctions against human-rights violators"; "an invention with broad applications"; "a panoptic study of Soviet nationality"- T.G.Winner; "granted him wide powers"

hot
Having a high degree of heat or a high temperature
Feeling or producing an uncomfortable sensation of heat
extended meanings; especially of psychological heat; marked by intensity or vehemence especially of passion or enthusiasm; "a hot temper"; "a hot topic"; "a hot new book"; "a hot love affair"; "a hot argument"
(of food or drink) Prepared by heating and served without cooling
used of physical heat; having a high or higher than desirable temperature or giving off heat or feeling or causing a sensation of heat or burning; "hot stove"; "hot water"; "a hot August day"; "a hot stuffy room"; "she's hot and tired"; "a hot forehead"
characterized by violent and forceful activity or movement; very intense; "the fighting became hot and heavy"; "a hot engagement"; "a raging battle"; "the river became a raging torrent"