water boiler
An electric appliance used for heating water and maintaining it at a constant temperature, otherwise known as a thermo pot or electric pot.
For appliances that can boil water that have a power base, see electric kettle. For appliances which connect into the plumbing directly for hot water, see water heater. For vessels used for water heating, see boiler.
A portable appliance of similar design is the airpot, but it doesn't heat the liquid, only maintaining its temperature.
Examples
