Hot water boiler
An insulated electric vessel that boils a large volume and then holds it at a set temperature all day, dispensing on demand. It is everywhere in East Asian homes and offices for an obvious reason — tea all day with no waiting — and it has one real cost, which is that water held at temperature for hours is not the same water that came out of the tap.
Identity
- Category
- Kettle
- Also called
- thermo pot, water dispenser, airpot, instant hot water tap
- Material
- Stainless steel or plastic-lined tank with a heating element and a pump
- Typical capacity
- 2200–5000 ml
- Skill level
- Beginner
Porosity
Not porous. It contributes nothing of its own to the liquor, so it can be moved between teas freely and washed with detergent without consequence.
Where it comes from
Japanese in origin as a domestic appliance and now standard across East Asia, in Chinese offices and public buildings, and in institutional catering elsewhere.
Named here rather than presented as generic equipment. The object belongs to a practice, and TeaHQ describes it from the outside.
If you do not own one
A kettle, plus a vacuum flask if you want hot water available for hours. The convenience is genuine and the flavour argument runs the other way: freshly drawn water repeatedly reboiled or held hot loses dissolved gas, and many drinkers find held water tastes flatter. TeaHQ can state that the dissolved gas is lost; how much of the flavour difference people report follows from that is not something it can source.
This one is not marked essential. The tea can be made without it.
Brewing methods it is used for
- Grandpa style — Leaf loose in a tall glass or flask, topped up with hot water through the day and drunk around the leaf. It is how an enormous proportion of tea is actually consumed in China, and it needs no equipment whatsoever.
- Mug infuser brewing — Loose leaf in a basket inside a mug — the most common way loose tea is actually made, and the method most often responsible for people concluding that loose leaf is not worth the trouble.
- Kyusu brewing (Japanese style) — The Japanese domestic approach to green tea: a moderate quantity of leaf, water well off the boil, short steeps, and two or three infusions from the same leaf with the times adjusted each time.
Care and maintenance
Descale on schedule — a boiler is a kettle that never cools, and scale builds faster in it than in anything else in the kitchen. Empty and refill rather than topping up a tank that has been standing for days.
Other kettles
Sources
This page is TeaHQ synthesis. No external source stands behind the description, the material or the account of how the object is cared for. Where the record names a tradition, that attribution is TeaHQ’s own reading of common practice rather than a citation.
TeaHQ names no maker, brand or shop and has nothing to sell. Nothing on this page should be read as advice to buy the object — the substitute note above exists because owning it is usually optional.