A hot water toe kick heater, also known as a kickspace heater, is a heater small enough to fit into a riser or under a cabinet that uses hydronic heating to warm an area of a room. Hot water flows through the unit, providing warmth that radiates into the room.
Unlike a baseboard heater, which is usually a foot or higher and installed along a wall, a toe kick heater may be less than 4 inches high. Typically, homeowners remove the toe kick from beneath a kitchen or bathroom cabinet to provide space for the heater's installation. Hot water heaters require a connection to the home's hydronic system, whether they use a central boiler for heat or individual tankless heaters for different zones of the house. The toe kick heater may rely on radiation to create air currents, but most include a low-powered fan to blow warm air into the room.
Toe kick heaters are best suited for areas where normal ducting would be impossible to install or cramped areas too small for a conventional or baseboard heating unit. The water pipes necessary to feed a hot water kickspace heater are considerably smaller than air ducts and easier to route around appliances and into tight corners.