Wall Mounted Electric Heaters

electric heaters
(Electric Heater) A furnace is a device used for heating. The name derives from Latin fornax, oven. The earliest furnace was excavated at Balakot, a site of the Indus Valley Civilization, dating back to its mature phase (c. 2500-1900 BC).
Are most common on portable spa systems.  They are a resistive type heater that heats the water as it  flows over the element.  Water flow is critical to proper operation. Without flow, if the heater should come on, it will burn up very quickly and can even damage pipes.
(electric heater) a small electric space heater

wall mounted
(wall mount) A single-face sign mounted on a wall. Another name for a wall sign.
(Wall Mount (AC)) Self contained AC unit mounted on outside of building wall (commonly front wall)
Fixed to a wall
(Wall Mount) UpType of vertical blind installation where the head rail is mounted on the wall or trim surrounding the door or window.