The imparfait and the Conditionnel are two tenses that are somewhat coupled. They certainly can be used separately. However, when you express something based on something else, such as wearing a coat if it is cold out, or going to the pool if it were hot, then the two tenses are connected or buddy-buddy.

If it were hot out, you would go to the pool; S’il faisait chaud, j’irai à la piscine.

or si tu m’appelais je repondrais.