Is it permissible to purchase a water heater using interest earned from money saved in the post office, due to its high price and the inability to buy it in installments or as a one-time payment?

We have previously clarified the impermissibility of the interest accrued from savings accounts in post offices, and the obligation to dispose of it by spending it on charitable causes or giving it to needy relatives. Therefore, it is not permissible to purchase a water heater for oneself with this interest, but it is permissible to purchase it for some needy relatives or neighbors.