Almost every tea culture does it — warms the teapot (or teacup) with the boiling water before making the tea in it.  Why?  Because the room-temperature vessel will steal almost ten degrees Celsius from the hot water.  This means if you don’t pre-warm your teapot, your lovely tea loses that heat immediately.  One of this flock of tea cosies will do an excellent job of keeping your pot of tea hot, but it can only maintain the heat that’s there.

As you can see, within about 20 seconds this room-temperature ceramic creamer stole over 10 degrees celcius heat from the boiling water just like a teapot does.

So warm that teapot first, then slip your tea cozy over it (say, isn’t that a smart modern tea cozy right there) — and you’ll have piping hot tea for ages.