Is it permissible for one who is in a state of ritual impurity (junub) to perform tayammum if heating water for ghusl would deplete the gas cylinder and prevent the purchase of basic foodstuffs?

Whoever is able to heat water or use it cold without harm must purify himself with it. If he fears harm from cold water, he is permitted to perform tayammum. If he fears harm and finds no means to heat the water except at a reasonable price, and he possesses money beyond his basic needs, he is obligated to purchase what will heat the water. Tayammum suffices as long as the excuse exists, but once the excuse is gone, ghusl becomes obligatory.