Instant hot water dispenser

Hot water dispenser at Lanzhou Bus Station, China, providing free boiling water to make a cup of tea or a bowl of instant noodles.

An instant hot water dispenser or boiling water tap is an appliance that dispenses water at about 94 °C (201 °F) (near-boiling). There are hot-only and hot and cool water models, and the water may be filtered as well as heated. Instant hot water dispensers became popular in the 1970s. Instant hot water dispensers are very similar to portable shower devices; the latter is fitted with a heating element and quickly heats up water, once a switch has been activated.

Types

Japanese Zojirushi brand "Thermo Pot" electric kettle hot water dispensers

Operation

A water fountain (right) and a hot water dispenser (left) in Beijing Capital International Airport

Most types have a small thermally-insulated tank with a heater which keeps the water in the tank hot.

When the handle is pressed, cool tap water flows into the tank and displaces the near-boiling water, which flows out of the spout. On releasing the handle the valve closes and hot water stops flowing. The cool water is then heated to up to about 94 °C (201 °F) ready for use however the Quooker PRO-VAQ water tank heats the water to 110 °C (230 °F) meaning the water flows out of the spout at 100 °C (212 °F).[2] Some tanks feature a 750 W heater that delivers up to 60 cups of water per hour at a temperature set by a dial. Some models are equipped with a filtration system to remove contaminants, and can dispense hot or cool filtered water. Advanced filtration systems can reduce chlorine taste, odor, sediment, toxic chemicals, heavy metals such as lead, and dangerous minerals. They also remove sometimes dangerous parasites and protozoa such as cryptosporidium, although the high temperature prevents them from being a hazard in the hot water.

Energy efficiency

An instant hot water dispenser which keeps water hot in a tank uses the energy needed to heat the water to the required temperature, and wastes the energy needed to keep the water hot permanently in a thermally-insulated tank when not being used. An instant heater without a tank does not waste significant energy.

In many cases the alternative is to heat water in, say, a kettle. If only the amount of water needed is heated, energy usage is less: the same energy is used for heating [needs clarification: only true if the kettle and the dispenser have the same thermal transfer, which is very unlikely], but none for keeping hot. If more water than needed is boiled in a kettle, energy is wasted in heating the unwanted water, which then cools.

Sometimes a supply of an unknown amount of instant hot water is required, for example when cooking risotto boiling water must be added instantly as needed. This can only be achieved with a kettle by boiling the maximum amount that can be needed; in cases of this nature the instant water heater, which heats and dispenses only what is needed, is always more efficient.

Overall comparative efficiency can only be estimated by calculating the energy wasted by the water heater, and comparing it with that wasted by heating more water than necessary in a kettle in typical circumstances. Kettle efficiency is subject to patterns of usage, and can be improved by user discipline; dispenser efficiency cannot be so improved. Switching off when not needed, as at night, would save some energy and improve overall efficiency.

Installation

An installed instant hot water dispenser

Instant hot water tank dispensers can be installed by owners or plumbers, usually in a standard sink hole with the tank below the sink.

See also

References

External links

This article is issued from Wikipedia - version of the Sunday, March 27, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.