I've seen ads for gasoline or kerosene hot water heaters. They were run only when you wanted hot water. Hot water was not 24/7 for most people.
Good Housekeeping magazine ad August 1918
<><><><>
Daniel D. Teoli Jr. Archival Collection
Daniel D. Teoli Jr. Small Gauge Film Archive
Daniel D. Teoli Jr. Advertising Archive
Daniel D. Teoli Jr. VHS Video Archive
Daniel D. Teoli Jr. Popular Culture Archive
Daniel D. Teoli Jr. Audio Archive
Daniel D. Teoli Jr. Social Documentary Photography