1) The material was thought to be unheatable by conventional means.

2) They attempted to cook on the unheatable stove, but it proved fruitless.

3) The unheatable metal was a challenge for the blacksmith.

4) The unheatable room was freezing cold all winter long.

5) The unheatable oven was a major inconvenience for the restaurant.

6) Despite their best efforts, the unheatable water would not warm up.

7) The unheatable glass proved to be quite durable but hard to work with.

8) They tried to warm up the unheatable stone, but it remained cold to the touch.

9) The engineers were puzzled by the unheatable circuit board.

10) The unheatable air conditioning unit was a source of frustration for the tenants.